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  • Technical note: Infusion, sampling, and vacuum-assisted collection devices for use in ruminally cannulated calves
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    T.T. Yohe, H. Schramm, C.L.M. Parsons, R.R. White, K.M. Daniels

    Calves can be ruminally cannulated at young ages, but equipment size limitations preclude use of an infusion and sampling device in these small animals. Likewise, a procedure to easily evacuate rumen contents in young calves has not been described. Overcoming these technical complications related to assessment of ruminal passage kinetics, nutrient digestion, and volatile fatty acid absorption would aid in future studies advancing our knowledge of dairy calf nutrition. The first objective was to design and fabricate 2 devices (one device for infusion and sampling, and another for vacuum-assisted collection) suitable for use in young ruminally cannulated dairy calves. The second objective was to test the utility of these tools when performing procedures commonly used in ruminant nutrition research. A single weaned 62-d-old ruminally cannulated calf was used to evaluate the ability to infuse a solution of LiCoEDTA and sample rumen contents through the cannula cap over a period of 2 h to assess the rumen liquid passage rate (procedure 1). The device was capable of infusing the LiCoEDTA and sampling the rumen fluid, as evidenced by the presence of elevated Co concentrations in the sampled rumen fluid. Using the fluid samples obtained, liquid passage rate within the calf was estimated to be 40.2% of ruminal fluid/h. The second procedure tested the vacuum-assisted collection device and consisted of evacuating and weighing the rumen contents, which is considered a key preparatory step in washed reticulorumen technique experiments that aim to measure nutrient absorption. In agreement with existing literature, evacuated rumen contents represented approximately 4% of the calf's body weight. In conclusion, custom-built devices for infusion, sampling, and vacuum-assisted collection were efficacious when tested in a 62-d-old ruminally cannulated calf fed a diet of 100% texturized starter (18% crude protein, as-fed). Fellow scientists may employ and further modify these techniques to suit their needs when assessing passage kinetics, nutrient digestion, and volatile fatty acid absorption in calves.

    更新日期:2018-07-20
  • Association of postpartum hypocalcemia with early-lactation milk yield, reproductive performance, and culling in dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    P.L. Venjakob, L. Pieper, W. Heuwieser, S. Borchardt

    Periparturient hypocalcemia is frequently observed and considered as a gateway disease that is associated with various health issues. The objective of this study was to evaluate the association of hypocalcemia with early-lactation milk yield, reproductive performance, and culling across a large number of different managerial systems. A prospective cohort study was conducted based on a convenience sample of 125 dairy herds from 8 federal states of Germany between February 2015 and August 2016. A blood sample was drawn from 1,709 animals within 48 h after parturition and analyzed for serum calcium concentration. After discarding cows (n = 283) with missing data, a total of 1,426 cows were considered for final analyses. The median time from calving to sampling was 14.0 h (interquartile range = 5.0–24.9 h). For each herd, a record of the herd management software was requested 150 d after the last cow was sampled. Serum calcium concentration of each cow was associated with early-lactation milk yield (Dairy Herd Improvement Association equivalent test 1 to 3), reproductive performance [days in milk (DIM) at first artificial insemination (AI), pregnancy at first AI, time to pregnancy within 150 DIM], and culling (until 60 DIM) data. Generalized linear mixed models were used to analyze continuous or categorical data. Shared frailty models were used for time to event data. Five different thresholds were used to define hypocalcemia. Thresholds ranged from 1.8 to 2.2 mmol/L using 0.1-mmol/L increments. Clinical hypocalcemia was defined as serum calcium concentration <2.0 mmol/L in combination with clinical signs (e.g., recumbency). The effect of hypocalcemia on milk yield was conditional on parity. In primiparous cows a serum calcium concentration <2.0 mmol/L (6.4% of cows were below this threshold) had no effect on milk production, whereas there was a tendency for multiparous cows with a serum calcium concentration <2.1 mmol/L (63.2% of cows were below this threshold) to produce 0.80 kg/d more milk compared with multiparous cows at or above the threshold. Multiparous cows suffering from clinical hypocalcemia produced 2.19 kg/d less milk compared with normocalcemic cows in early lactation. Calcium status was not associated with days to first insemination. Cows with a serum calcium concentration <1.9 mmol/L (34.6% of cows below this threshold) had decreased odds (odds ratio = 0.56) of pregnancy at first AI. A serum calcium concentration <1.8 mmol/L (24.1% of cows below this threshold) had a significant effect on time to pregnancy. Compared with animals with a serum calcium concentration ≥1.8 mmol/L, the hazard of becoming pregnant within 150 DIM was reduced when cows had a serum calcium concentration <1.8 mmol/L (hazard ratio = 0.68). Cows with a serum calcium concentration <2.0 mmol/L (44.3% of cows were below this threshold) had a 1.69 times greater hazard of being culled within the first 60 DIM compared with normocalcemic animals. The present study shows that the association of hypocalcemia with milk yield was conditional on parity and serum calcium concentration measured once within 48 h after calving. Considering reproductive performance and culling in early lactation, a negative effect of postpartum hypocalcemia was demonstrated.

    更新日期:2018-07-20
  • The association of lipophilic phospholipids with native bovine casein micelles in skim milk: Effect of lactation stage and casein micelle size
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    M. Cheema, P.B. Smith, A.D. Patterson, A. Hristov, F.M. Harte

    A known biological role of casein micelles is to transport calcium from mother to young and provide amino acids for growth and development. Previous reports demonstrated that modified casein micelles can be used to transport and deliver hydrophobic probes. In this study, the distribution of lipid-soluble phospholipids, including sphingomyelins (SM) and phosphatidylcholines (PC), was quantified in whole raw milk, skim raw milk, and casein micelles of various sizes during early, mid, and late lactation stages. Low-pressure size exclusion chromatography was used to separate casein micelles by size, followed by hydrophobic extraction and liquid chromatography–mass spectrometry for the quantification of PC and SM. Results showed that the SM d18:1/23:0, d18:1/22:0, d18:1/16:0, d16:1/22:0, d16:1/23:0, and d18:1/24:0 and the PC 16:0/18:1, 18:0/18:2, and 16:0/16:0 were dominating candidates appearing in maximum concentration in whole raw milk obtained from late lactation, with 21 to 50% of total SM and 16 to 35% of total PC appearing in skim milk. Of the total SM and PC found in skim milk, 35 to 46% of SM and 22 to 29% of PC were associated with the casein micelle fraction. The highest concentrations of SM d18:1/22:0 (341 ± 17 μg/g of casein protein) and PC 16:0/18:1 (180 ± 20 μg/g of casein protein) were found to be associated with the largest casein micelles (diameter = 149 nm) isolated in milk from late lactation, followed by a decrease in concentration as the casein micelle size decreased.

    更新日期:2018-07-20
  • Determination of quantitative trait nucleotides by concordance analysis between quantitative trait loci and marker genotypes of US Holsteins
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    J.I. Weller, D.M. Bickhart, G.R. Wiggans, M.E. Tooker, J.R. O'Connell, J. Jiang, M. Ron, P.M. VanRaden

    Experimental designs that exploit family information can provide substantial predictive power in quantitative trait nucleotide discovery projects. Concordance between quantitative trait locus genotype as determined by the a posteriori granddaughter design and marker genotype was determined for 30 trait-by-chromosomal segment effects segregating in the US Holstein population with probabilities of <10−20 to accept the null hypotheses of no segregating gene affecting the trait within the chromosomal segment. Genotypes for 83 grandsires and 17,217 sons were determined by either complete sequence or imputation for 3,148,506 polymorphisms across the entire genome; 471 Holstein bulls had a complete genome sequence, including 64 of the grandsires. Complete concordance was obtained only for stature on chromosome 14 and daughter pregnancy rate on chromosome 18. For each quantitative trait locus, effects of the 30 polymorphisms with highest concordance scores for the analyzed trait were computed by stepwise regression for predicted transmitting abilities of 26,750 bulls with progeny test and imputed genotypes. Effects for stature on chromosome 11, daughter pregnancy rate on chromosome 18, and protein percentage on chromosome 20 met 3 criteria: complete or almost complete concordance, nominal significance of the polymorphism effect after correction for all other polymorphisms, and marker coefficient of determination >40% of total multiple-regression coefficient of determination for the 30 polymorphisms with highest concordance. An intronic variant marker on chromosome 5 at 93,945,738 bp explained 7% of variance for fat percentage and 74% of total multiple-marker regression variance but was concordant for only 24 of 30 families. The missense polymorphism Phe279Tyr in GHR at 31,909,478 bp on chromosome 20 was confirmed as the causative mutation for fat and protein concentration. For effect on fat percentage on chromosome 14, 12 additional missense polymorphisms were found that had almost complete concordance with the suggested causative polymorphism (missense mutation Ala232Glu in DGAT1). The only polymorphism found likely to improve predictive power for genomic evaluation of dairy cattle was on chromosome 15; that polymorphism had a frequency of 0.45 for the allele with economically positive effects on all production traits.

    更新日期:2018-07-20
  • Measuring labor input on pasture-based dairy farms using a smartphone
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    J. Deming, D. Gleeson, T. O'Dwyer, J. Kinsella, B. O'Brien

    With the cessation of milk quotas in the European Union, dairy herd sizes increased in some countries, including Ireland, with an associated increase in labor requirement. Second to feed costs, labor has been identified as one of the highest costs on pasture-based dairy farms. Compared with other European Union countries, Ireland has historically had low milk production per labor unit; thus, optimization of labor efficiency on farm should be addressed before or concurrently with herd expansion. The objective of this study was to quantify current levels of labor input and labor efficiency on commercial pasture-based dairy farms and to identify the facilities and management practices associated with increased labor efficiency. Thirty-eight dairy farms of varying herd sizes, previously identified as labor-efficient farms, were enrolled on the study and data were collected over 3 consecutive days each month over a 12-mo period, starting in May 2015 and finishing in August of 2016. This was achieved through the use of a smartphone application. For analysis purposes, farms were categorized into 1 of 3 herd size categories (HSC): farms with <150 cows (HSC 1), 150–249 cows (HSC 2), or ≥250 cows (HSC 3). Overall farm labor input increased with HSC with 3,015, 4,499, and 6,023 h worked on HSC 1, 2, and 3, respectively. A higher proportion of work was carried out by hired staff as herd size increased. Labor efficiency was measured as total hours input to the dairy enterprise divided by herd size. Labor efficiency improved as herd size increased above 250 cows with 17.3 h/cow per yr observed for HSC 3; labor efficiency was similar for HSC 1 and 2, at 23.8 and 23.3 h/cow per yr, respectively. A large range of efficiency was observed within HSC. The labor requirements had a distinct seasonal pattern across the 3 HSC with the highest input observed in springtime (February to April) primarily due to calving and calf-care duties, milking, and winter feeding. The lowest input was observed in wintertime (November to January) when cows were dry. Particular facilities and management practices were associated with efficiency within certain tasks, the most notable in regard to milking and winter feeding practices. Additionally, the most efficient farms used contractors to perform a higher proportion of machinery work on farm than the least efficient farms.

    更新日期:2018-07-20
  • Supplementing phytogenic compounds or autolyzed yeast modulates ruminal biogenic amines and plasma metabolome in dry cows experiencing subacute ruminal acidosis
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    E. Humer, I. Kröger, V. Neubauer, K. Schedle, N. Reisinger, Q. Zebeli

    Subacute ruminal acidosis (SARA) causes ruminal dysbiosis, thereby increasing the risk of systemic metabolic disorders in cattle. We recently showed that supplementation with phytogenic compounds (PHY) or autolyzed yeast (AY) counteracted negative effects of SARA by improving ruminal pH and microbiome. This study investigated the effects of an intermittent SARA challenge on the ruminal concentration of biogenic amines (BA) and lipopolysaccharides (LPS), as well as on the blood metabolome. We also evaluated effects of PHY and AY on the latter variables. Eight rumen-cannulated nonlactating Holstein cows were arranged in an incomplete 4 × 3 Latin square design with 4 experimental runs and 3 treatment groups. During each run, cows were switched from an all-forage diet (baseline) to an intermittent concentrate-challenge diet with a forage:concentrate ratio of 35:65 (dry matter basis) to induce SARA for 1 (SARA1) or 2 (SARA2) wk, separated by 1 wk of forage-only feeding. The 3 treatment groups were no additive as control, PHY, or AY. During baseline, SARA1 and SARA2 rumen fluid samples were collected for analysis of BA and LPS. Blood samples were taken during baseline and SARA1 for a targeted metabolomics approach. High-concentrate feeding caused a 9-fold increase in ruminal LPS during SARA1 and an 11-fold increase in SARA2 compared with the baseline. Elevated concentrations of ruminal BA were found during both SARA periods, with histamine showing the strongest increase during SARA1. Moreover, a decrease in phosphatidylcholines, lysophosphatidylcholines, sphingomyelines, and several AA in the blood during SARA1 were detected. Supplementation of PHY decreased concentrations of LPS (−43%), histamine (−66%), pyrrolidine (−38%), and spermine (−54%) in SARA1 and cadaverine in SARA2 (−50%). Moreover, cows that received PHY had higher concentrations of cholesterol (+26%), several AA, and phosphatidylcholines in SARA1 compared with control cows. For AY, decreases in ruminal ethanolamine (−21%), methylamine (−52%), histamine (−54%), spermidine (−44%), and spermine (−80%) in SARA1 were observed, whereas in the blood an increase in tryptophan was noticed. In conclusion, the SARA was associated with markedly increased concentrations of LPS and BA in the rumen fluid and undesirable shifts in the plasma metabolome. Supplementation of PHY and AY counteracted some of these changes and therefore may help in attenuating negative effects of high-concentrate feeding in dairy cattle.

    更新日期:2018-07-20
  • Effects of growth stage and growing degree day accumulations on triticale forages: 1. Dry matter yield, nutritive value, and in vitro dry matter disappearance
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    W.K. Coblentz, M.S. Akins, K.F. Kalscheur, G.E. Brink, J.S. Cavadini

    The use of triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly to improve land stewardship by providing winter ground cover. Our objective was to establish relationships relating indices of nutritive value with growth stage or accumulated growing degree days >5°C for triticale forages grown in central Wisconsin. Replicated 3.7-m × 9.1-m plots were established following removal of corn for silage (fall 2015) and soybeans (fall 2016) and then harvested at various growth stages the following spring. Plants were assigned a numerical growth stage based on a linear staging system suitable for use as an independent regression variable. Response variables [e.g., dry matter (DM) yield, indices of nutritive value, and parameters from in vitro DM disappearance kinetics] were regressed on growth stage and growing degree days using linear, quadratic, cubic, or quartic models. For spring 2016, the mean DM yield at the boot stage (3,804 kg of DM/ha) was only 30% of that observed at the soft dough stage of growth (12,642 kg of DM/ha). Although yields were reduced during spring 2017, primarily due to spring flooding, the relationship between respective yields at these growth stages was similar (1,453 vs. 5,399 kg of DM/ha). Regressions of DM yield (kg/ha) on growth stage for 2016 were explained by a cubic model (Y = 0.0663x3 − 9.44x2 + 595x − 9,810) compared with a simple linear response for 2017 (Y = 103x − 3,024); in both cases, coefficients of determination were very high (R2 ≥ 0.934). Many nutritional and in vitro DM disappearance characteristics were affected by the juxtaposition and balance of 2 generally competing factors: (1) increased concentrations of structural plant fiber coupled with concurrent lignification as plants matured and (2) the accumulation of highly digestible carbohydrate during seed head development. A comparison of respective energy yields between the boot and soft dough stages of growth for 2016 (2,488 vs. 8,141 kg of total digestible nutrients/ha) and 2017 (1,033 vs. 3,520 kg of total digestible nutrients/ha) suggests that yields of energy are greater at soft dough stage and are mostly driven by DM yield. An informed harvest management decision for lactating cows may still favor a boot-stage harvest because of superior nutritional characteristics, a need to plant double-cropped corn expeditiously, or both. Harvest timing of triticale forages for other livestock classes would appear to be more flexible, but prioritizing a subsequent double crop may reduce the effects on DM yield to a secondary consideration.

    更新日期:2018-07-20
  • The relationship between serum insulin-like growth factor-1 (IGF-1) concentration and reproductive performance, and genome-wide associations for serum IGF-1 in Holstein cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    M. Gobikrushanth, D.C. Purfield, M.G. Colazo, Z. Wang, S.T. Butler, D.J. Ambrose

    The objectives of this study were to determine (1) factors associated with serum concentration of insulin-like growth factor-1 (IGF-1); (2) the relationship between serum IGF-1 concentration during the first week postpartum and ovarian cyclicity status by 35 d postpartum (DPP); (3) an optimum serum IGF-1 concentration threshold predictive of pregnancy to first artificial insemination (P/AI), including its diagnostic values; (4) the associations among categories of serum IGF-1 concentration and reproductive outcomes (P/AI and pregnancy risk up to 150 and 250 DPP); and (5) single nucleotide polymorphisms (SNP) associated with phenotypic variation in serum IGF-1 concentration in dairy cows. Serum IGF-1 concentration was determined at 7 (±2.4; ±standard error of the mean) DPP in 647 lactating Holstein cows (213 primiparous, 434 multiparous) from 7 herds in Alberta, Canada. The overall mean, median, minimum, and maximum serum IGF-1 concentrations during the first week postpartum were 37.8 (±1.23), 31.0, 20.0, and 225.0 ng/mL, respectively. Herd, age, parity, precalving body condition score, and season of blood sampling were all identified as factors associated with serum IGF-1 concentrations. Although serum IGF-1 concentration during the first week postpartum had no association with ovarian cyclicity status by 35 DPP in primiparous cows, it was greater in cyclic than in acyclic multiparous cows (32.2 vs. 27.4 ng/mL, respectively). The optimum serum IGF-1 thresholds predictive of P/AI were 85.0 ng/mL (sensitivity = 31.9%; specificity = 89.1%) and 31.0 ng/mL (sensitivity = 45.5%; specificity = 66.9%) for primiparous and multiparous cows, respectively. When cows were grouped into either high or low IGF-1 categories (greater or less than or equal to 85.0 ng/mL for primiparous cows and greater or less than or equal to 31.0 ng/mL for multiparous cows, respectively), primiparous cows with high IGF-1 had 4.43 times greater odds of P/AI and a tendency for higher pregnancy risk up to 150 DPP than those with low IGF-1, but not up to 250 DPP. Likewise, multiparous cows with high IGF-1 had 1.61 times greater odds of P/AI than those with low IGF-1. Pregnancy risk up to 150 and 250 DPP, however, did not differ between IGF-1 categories in multiparous cows. Moreover, 37 SNP across 10 Bos taurus autosomes were associated with variation in serum IGF-1 concentration, and 4 previously identified candidate genes related to fertility that were in linkage disequilibrium with some of these SNP were also identified.

    更新日期:2018-07-20
  • Effects of mixing red clover with alfalfa at different ratios on dynamics of proteolysis and protease activities during ensiling
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    Xujiao Li, Jipeng Tian, Qing Zhang, Yun Jiang, Zhe Wu, Zhu Yu

    This study was conducted to study the effects of ensiled alfalfa (Medicago sativa) and red clover (Trifolium pretense) at different ratios on dynamics of fermentation parameters, N distribution, protein fractions, and protease activities during ensiling. Alfalfa and red clover were harvested and wilted to 35 and 25% dry matter, respectively, chopped to 1 cm, mixed, weighed into 1.0-L buckets at a density of 700 g/L, and ensiled for 1, 3, 7, 15, and 30 d at 30°C. The treatments were mixing ratio of alfalfa to red clover at 100:0, 70:30, 50:50, 30:70, and 0:100 (R0, R30, R50, R70, and R100, respectively; fresh weight). For each ensiling duration, 3 replicates of each treatment were prepared. With increasing proportion of red clover in silage, total N content and proportions of nonprotein N, peptide N, free amino acid N, and NH3-N decreased linearly, and PC (indigestible true protein, acid detergent insoluble N) proportion increased linearly after ensiling. Moreover, the final pH was lower in R50 and R100 than R0 (4.29, 4.20 vs. 4.48, respectively) on d 30. Also, lactic acid concentration on d 30 was higher in R50, R70, and R100 silage compared with R0 (7.77, 7.66, and 8.76 vs. 6.34, % of dry matter, respectively). The proportion of NH3-N in R50 was lower than in R0 but closer to R100 after ensiling. During ensiling, proteases including carboxypeptidase, aminopeptidase, and acid proteinase activities decreased as red clover proportion increased. However, no differences were detected in aminopeptidase and acid proteinase activities among R50, R70, and R100 during ensiling. Overall, 50:50 was the optimal mixing ratio of alfalfa with red clover, showing good fermentation quality with lower pH and higher lactic acid concentration, reduced protease activities and proteolysis compared with pure alfalfa silage, and also more total N content than pure red clover silage.

    更新日期:2018-07-20
  • Antimicrobial susceptibility patterns of Escherichia coli phylogenetic groups isolated from bovine clinical mastitis
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-19
    T. Tomazi, F.M. Coura, J.L. Gonçalves, M.B. Heinemann, M.V. Santos

    Determination of antimicrobial susceptibility (AMS) of Escherichia coli causing clinical mastitis (CM) according to the phylogenetic groups and its association with descriptors at the cow and herd level may help improve specific strategies for treatment and control of this pathogen in dairy herds. The aims of the present study were to (a) determine the frequency of phylogenetic groups of E. coli isolated from CM in dairy cows, and its association with cow-level descriptors (parity, lactation stage, CM severity, and affected quarter position), housing system, and season; and (b) determine and compare AMS among E. coli phylogenetic groups. A quadruplex PCR method was used to classify E. coli isolates into 1 of the 7 phylogenetic groups. Minimal inhibitory concentrations were determined for 10 antimicrobials, and survival analysis was performed to evaluate the AMS differences among E. coli phylogroups. Most E. coli isolates belonged to phylogroups A (52%) and B1 (38%). None of the cow- and herd-level descriptors were associated with the E. coli phylogenetic groups. Overall, E. coli isolates were mostly susceptible to ceftiofur (96.8%), sulfadimethoxine (75.5%), and cephalothin (74.5%). Based on the survival analysis, differences in AMS between phylogenetic groups of E. coli was observed only for cephalothin, in which strains of phylogroup A were inhibited at lower minimum inhibitory concentration than strains of phylogroup B1. Results of this study indicated low susceptibility of E. coli isolates identified from CM to most antimicrobials. In addition, differences in AMS can occur among E. coli phylogenetic groups, although they may be uncommon as they were limited to only one antimicrobial (i.e., cephalothin).

    更新日期:2018-07-20
  • Feed and nitrogen efficiency are affected differently but milk lactose production is stimulated equally when isoenergetic protein and fat is supplemented in lactating dairy cow diets
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    K. Nichols, A. Bannink, S. Pacheco, H.J. van Valenberg, J. Dijkstra, H. van Laar

    Fifty-six Holstein-Friesian cows were used in a randomized complete block design to test the effects of supplemental energy from protein (PT) and fat (FT) on lactation performance and nutrient digestibility in a 2 × 2 factorial arrangement. During the control period, cows were adapted for 28 d to a basal total mixed ration consisting of 34% grass silage, 33% corn silage, 5% grass hay, and 28% concentrate on a dry matter (DM) basis. Experimental rations were fed for 28 d immediately following the control period and consisted of (1) low protein, low fat (LP/LF), (2) high protein, low fat (HP/LF), (3) low protein, high fat (LP/HF), or (4) high protein and high fat (HP/HF). To obtain the HP and HF diets, intake of the basal ration was restricted and supplemented isoenergetically (net energy basis) with 2.0 kg/d of rumen-protected protein (soybean + rapeseed, 50:50 mixture on DM basis) and 0.68 kg/d of hydrogenated palm fatty acids (FA) on a DM basis. Milk production and composition, nutrient intake, and apparent digestibility were measured during the final 7 d of the control and experimental periods. No interaction was found between PT and FT on milk production and composition. Yields of milk, fat- and protein-corrected milk, and lactose increased in response to PT and FT and lactose concentration was unaffected by treatment. Milk protein concentration and yield increased in response to PT, and protein yield tended to increase in response to FT. Milk fat concentration and yield increased in response to FT and were unaffected by PT. Milk urea concentration increased and nitrogen efficiency decreased in response to PT. Feed and nitrogen efficiency were highest on the LP/HF diet and both parameters increased in response to FT, whereas milk urea concentration was not affected by FT. Energy from fat increased the concentration and yield of ≥16-carbon FA in milk and decreased the concentration of FA synthesized de novo, but had no effect on their yield. Concentration and yield of de novo-synthesized FA increased in response to PT. Concentration and yield of polyunsaturated FA increased and decreased in response to PT and FT, respectively. Apparent total-tract digestibility of crude fat decreased in response to PT, and FT increased crude protein digestibility. Energy supplementation through rumen-inert hydrogenated palm FA appears to be an efficient feeding strategy to stimulate milk production with regard to feed and nitrogen efficiency compared with supplementing an isoenergetic level of rumen-protected protein.

    更新日期:2018-07-14
  • Short communication: Association analysis of diacylglycerol acyltransferase (DGAT1) mutation on chromosome 14 for milk yield and composition traits, somatic cell score, and coagulation properties in Holstein bulls
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    T. Bobbo, F. Tiezzi, M. Penasa, M. De Marchi, M. Cassandro

    The aim of the present study was to determine the allele frequencies of the diacylglycerol acyltransferase (DGAT1) K232A mutation in Italian Holstein bulls and to estimate the effect of the mutation on milk yield, composition, somatic cell score, and coagulation traits (rennet coagulation time and curd firmness). For this purpose, 349 Italian Holstein bulls were genotyped for the DGAT1 mutation on chromosome 14. Association analysis was performed by regressing the number of copies for the K allele on the deregressed estimated breeding value of the individual. Breeding values were calculated using field data routinely collected in Northeast Italy. The frequencies of the AA, KA, and KK genotypes were 59.6, 32.1, and 8.3%, respectively, and the minor allele frequency (K variant) was 24.7%. The K allele was significantly associated with greater fat yield and fat, protein, and casein percentages and with reduced protein:fat ratio. The association between the DGAT1 mutation and somatic cell score was not significant, whereas a favorable association between presence of the K allele and milk coagulation properties was found. Results from the present study confirmed the effect of the diallelic DGAT1 polymorphism K232A on milk production traits and, for the first time, provided evidence that this mutation also affects milk coagulation properties in the Italian Holstein breed.

    更新日期:2018-07-14
  • Validating intrinsic markers and optimizing spot sampling frequency to estimate fecal outputs
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    D.L. Morris, L.R. Rebelo, P.A. Dieter, C. Lee

    Indirect methods of spot sampling with intrinsic markers to estimate fecal output and nutrient digestibility often have been used in dairy nutrition research as alternatives to total collection of feces (TC) because of labor and expense. However, fecal output and nutrient digestibility estimated from the indirect method must be accurate regardless of altering dietary conditions. This experiment was designed to validate the accuracy of using indigestible neutral detergent fiber (iNDF) or acid-insoluble ash (AIA) as intrinsic markers to estimate fecal outputs and nutrient digestibility compared with TC and to determine the optimal number of spot sampling events to accurately determine fecal output and then nutrient excretion. The experiment used 12 multiparous lactating Holstein cows in a randomized complete block design. Cows were blocked by days in milk and milk yield and randomly assigned to 1 of 2 diets: a diet containing about 49% corn silage on a dry matter basis and a diet containing about 48% alfalfa silage with high by-product (soyhulls) and supplemental K. During the final 3 d of 21-d periods, TC was performed, and 12 spot samples were collected for the same 3 d to represent every 2 h in a 24-h cycle. Fecal outputs and nutrient digestibility of dry matter, organic matter, or nitrogen estimated with iNDF or AIA as an intrinsic marker were compared with TC. Overall, fecal outputs and digestibility estimated with iNDF were similar to that estimated with TC, whereas AIA overestimated fecal output by 44 to 61% and underestimated nutrient digestibilities by 16 to 32%. However, potential differences in statistical inference of dietary effects between iNDF and TC were found. Data from individual spot samples were aggregated to represent spot sampling frequencies of 12 (SP12), 6 (SP6), 4 (SP4), or 2 (SP2) evenly spaced events starting at feeding time. Compared with TC, SP12 produced similar fecal content of iNDF, organic matter, and nitrogen, but fecal AIA content was greater. Furthermore, compared with SP12, SP6 produced similar fecal content of all nutrients, whereas marker and nutrient concentrations in SP4 and SP2 were different. In this experiment, iNDF was a better fecal marker than AIA, and a spot sampling frequency of at least 6 events was necessary. However, interpretation of dietary effects could be confounded when iNDF was used to estimate fecal outputs.

    更新日期:2018-07-14
  • Short communication: Occurrence of methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci in dairy goat herds in Ohio, United States
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    G.S. Moura, W.A. Gebreyes, M.F.S. Marques, D.T. Stipp, F.N. Souza, L.B. Da Costa, C.J.B. Oliveira

    In light of the scarcity of information about the occurrence and epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (MRCNS) in small ruminants in general, and particularly dairy goats, we launched this limited-scope study. The findings reported here show the detection of MRSA and MRCNS in goat milk and teat skin samples from dairy goat herds in the state of Ohio. A total of 120 milk samples and 120 teat-swab samples were collected from 5 farms. After conventional isolation and phenotypic characterization of the staphylococci colonies, bacterial isolates were tested by PCR assay targeting the genes nuc to identify Staphylococcus aureus and mecA to detect MRSA and MRCNS. The clonal complexes of MRSA isolates was also determined by multiloccus sequence typing. Fifteen (6.2%) positive S. aureus samples were found in this study: 9 from milk and 6 from teat skin samples. Four (2%) MRSA isolates were detected and, using multiloccus sequence typing genotyping, these were designated to clonal complexes CC133 (n = 2; milk samples) and CC5 (n = 2; teat skin). Three (1.25%) coagulase-negative staphylococci isolates from the teat skin also harbored the mecA gene. Although, the MRSA isolated from milk samples is not a typical human-associated lineage, the CC5 clone isolated from teat skin is a common and widespread clonal complex associated with humans, suggesting that this extramammary niche could be a relevant reservoir of methicillin-resistant staphylococci. Furthermore, the fact that 75% of MRSA were recovered from 1 farm showing poor hygiene practices strengthens the hypothesis that good hygiene practices could be useful to prevent persistence and spread of MRSA at a farm level.

    更新日期:2018-07-14
  • Technical note: Methodological and feed factors affecting measurement of protein A, B, and C fractions, degradation rate, and intestinal digestibility of rumen-undegraded protein
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    D.M. Liebe, J.L. Firkins, H. Tran, P.J. Kononoff, R.R. White

    When formulating dairy cow rations, characterization of protein in feeds requires estimation of protein degradation in the rumen and digestion in the intestine. The objective of this work was to evaluate experimental and feed-related factors that affect characterization using in situ, in vitro, or mobile bag techniques, of 0-h washout (A), potentially degradable (B), and undegradable (C) protein fractions, protein degradation rate (Kd), and digestibility of rumen undegradable protein (dRUP). Data sets of 136 studies on A, B, C, and Kd and 113 studies on dRUP were amassed from the literature. Mixed-effect linear models were used to relate these variables to methodological and feed factors while accounting for random differences among studies. Predictions of A, B, and C protein fractions were significantly influenced by crude protein and neutral detergent fiber interactions with bag pore size, incubation time, bag area, and sample-to-bag area ratio. For example, a 20.0% decrease in crude protein of a theoretical legume silage sample would increase A fraction prediction by 20.1%, but 34.7% with bag incubation time −1 standard deviation below the mean. Similarly, reported Kd values were significantly influenced by crude protein interactions with bag area and sample-to-bag area ratio and by neutral detergent fiber interaction with pore size. Feed variables and measurement variables influencing protein digestibility measures suggest that these analytical factors are likely associated with variance among differing methodologies and within unique samples of the same feed. When predicting dRUP, the use of mobile bag method produced significantly different estimates compared with the in vitro 3-step method. The use of mobile bag resulted in an 8.9% (±3.8%) higher estimate of dRUP compared with the in situ technique. In 618 and 977 samples, sample variation to sample mean ratio for acid detergent fiber and pepsin-acid incubation time was 63.0 and 58.0%, respectively. Variation in feedstuff content and lack of standardization of methods used to measure protein disappearance led to a lack of robustness in the measurements commonly employed.

    更新日期:2018-07-14
  • Short communication: Parapoxvirus and Orthopoxvirus coinfection in milk of naturally infected cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    Izabelle S. Rehfeld, Ana Luiza S. Fraiha, Ana Carolina D. Matos, Aristóteles G. Costa, Grazielle C.F. Gallinari, Érica A. Costa, Maria Isabel M.C. Guedes, Zélia Inês P. Lobato

    Several studies have shown the occurrence of poxvirus infections associated with exanthematic lesions in cattle from many Brazilian states. Coinfection between viruses belonging to 2 genera, Orthopoxvirus (OPXV) and Parapoxvirus (PPV), was already identified from the lesions of affected cows and humans. The DNA and infectious viral particles of Vaccinia virus, an OPXV, have been detected in milk of naturally and experimentally infected cows. However, to date no reports have described the detection of Pseudocowpox virus, a PPV, in milk. Thus, we investigated the presence of PPV and OPXV in milk samples obtained from dairy cows from a Brazilian region with exanthematic disease outbreaks. From 2011 to 2014, 6 dairy farms with exanthematic disease outbreaks involving dairy cows, calves, and humans were visited. Twelve crusts of cows' teat lesions and 60 milk samples were collected. The crusts and milk samples were analyzed by PCR to detect OPXV or PPV DNA. According to the analyzed crusts, we detected PPV infection in 4 of the 6 visited farms, from which we investigated the PPV contamination in milk. From the 40 milk samples tested, PPV DNA was detected in 12 samples. Of these milk samples, 8 were positive for both PPV and OPXV. This is the first report of PPV DNA detection in milk samples from affected cows, indicating that the virus may be present in milk and potentially contaminating dairy products associated or not with OPXV. In addition to the lesions caused by direct contact, the presence of 2 or more poxvirus species in milk showed that the effect of zoonotic exanthematic diseases on public health and animal husbandry is relevant and cannot be overlooked.

    更新日期:2018-07-14
  • Short communication: Relationship between body condition score and plasma adipokines in early-lactating Holstein dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    M. Mansouryar, H. Mirzaei-Alamouti, M. Dehghan Banadaky, H. Sauerwein, M. Mielenz, M.O. Nielsen

    We hypothesized that plasma adipokine concentrations of early-lactation dairy cows are related to body condition score (BCS) at calving and to markers of metabolic status of the cow. As part of a larger study with 117 multiparous Holstein dairy cows, which had high BCS (BCS >4.0) or normal BCS (3.25–3.5) at calving, 22 cows were randomly selected (n = 11 per group) to be enrolled in this study. Cows were divided into 2 groups based on their BCS at calving: (1) normal BCS with BCS of 3.35 ± 0.13 (mean ± SD) and (2) high BCS cows with BCS of 4.14 ± 0.17. The 22 selected animals did not have a clinically diagnosed health problem after calving. Blood samples were taken right after calving (d 1) and before morning feeding on d 8, 15, and 21 postpartum concurrently with body condition scoring for all cows. Blood samples were analyzed for plasma adiponectin, leptin, tumor necrosis factor-α, and IL-6. The mean BCS remained highest in high-BCS cows during the first 21 d in milk. Leptin concentrations decreased progressively for all cows after calving. However, differences in BCS at calving were not related to leptin concentrations. Adiponectin, IL-6, and tumor necrosis factor-α concentrations were neither influenced by days in milk nor BCS after calving. Leptin and the leptin-to-adiponectin ratio did not show any correlation at any time point during the first 21 d in milk with plasma concentrations of nonesterified fatty acids or β-hydroxybutyrate, which are considered as markers of metabolic status. Only for IL-6 at d 8 did we find a strong correlation with metabolic status indicators. In conclusion, plasma adipokine concentrations during the first 3 wk postpartum were not related to BCS in lactating Holstein cows that were clinically healthy at calving.

    更新日期:2018-07-14
  • Genomic heritability and genome-wide association analysis of anti-Müllerian hormone in Holstein dairy heifers
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    M.Y. Nawaz, F. Jimenez-Krassel, J.P. Steibel, Y. Lu, A. Baktula, N. Vukasinovic, L. Neuder, J.L.H. Ireland, J.J. Ireland, R.J. Tempelman

    Anti-Müllerian hormone (AMH) is an ovarian growth factor that plays an important role in regulation of ovarian follicle growth. The objectives of this study were to estimate the genomic heritability of AMH and identify genomic regions associated with AMH production in a genome-wide association (GWA) analysis. Concentrations of AMH were determined in 2,905 dairy Holstein heifers genotyped using the Zoetis medium density panel (Zoetis Inclusions, Kalamazoo, MI) with 54,519 single nucleotide polymorphism (SNP) markers remaining after standard genotype quality control edits. A linear mixed model was used to model the random effects of sampling day and genomics on the logarithm of AMH. The genomic heritability (± standard error of the mean) of AMH was estimated to be 0.36 ± 0.03. Our GWA analysis inferred significant associations between AMH and 11 SNP markers on chromosome 11 and 1 SNP marker on chromosome 20. Annotated genes with significant associations were identified using the Ensembl genome database (version 88) of the cow genome (version UMD 3.1; https://www.ensembl.org/biomart). Gene set enrichment analysis revealed that 2 gene ontology (GO) terms were significantly enriched in the list of candidate genes: G-protein coupled receptor signaling pathway (GO:0007186) and the detection of chemical stimulus involved in sensory perception (GO:0050907). The estimated high heritability and previously established associations between AMH and ovarian follicular reserve, fertility, longevity, and superovulatory response in cattle implies that AMH could be used as a biomarker for genetic improvement of reproductive potential.

    更新日期:2018-07-14
  • Ruminal biohydrogenation and abomasal flow of fatty acids in lactating cows fed diets supplemented with soybean oil, whole soybeans, or calcium salts of fatty acids
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-12
    J.E. Freitas, C.S. Takiya, T.A. Del Valle, R.V. Barletta, B.C. Venturelli, T.H.A. Vendramini, R.D. Mingoti, G.D. Calomeni, R. Gardinal, J.R. Gandra, V.P. Bettero, E. Ferreira de Jesus, M.D.S. Oliveira, F.P. Rennó

    Ruminants have a unique metabolism and digestion of unsaturated fatty acids (UFA). Unlike monogastric animals, the fatty acid (FA) profile ingested by ruminants is not the same as that reaching the small intestine. The objective of this study was to evaluate whole raw soybeans (WS) in diets as a replacer for calcium salts of fatty acids (CSFA) in terms of UFA profile in the abomasal digesta of early- to mid-lactation cows. Eight Holstein cows (80 ± 20 d in milk, 22.9 ± 0.69 kg/d of milk yield, and 580 ± 20 kg of body weight; mean ± standard deviation) with ruminal and abomasal cannulas were used in a 4 × 4 Latin square experiment with 22-d periods. The experiment evaluated different fat sources rich in linoleic acid on ruminal kinetics, ruminal fermentation, FA abomasal flow, and milk FA profile of cows assigned to treatment sequences containing a control (CON), with no fat source; soybean oil, added at 2.68% of diet dry matter (DM); WS, addition of WS at 14.3% of diet DM; and CSFA, addition of CSFA at 2.68% of diet DM. Dietary fat supplementation had no effect on nutrient intake and digestibility, with the exception of ether extract. Cows fed fat sources tended to have lower milk fat concentration than those fed CON. In general, diets containing fat sources tended to decrease ruminal neutral detergent fiber digestibility in relation to CON. Cows fed WS had lower ruminal digestibility of DM and higher abomasal flow of DM in comparison to cows fed CSFA. As expected, diets containing fat supplements increased FA abomasal flow of C18:0 and total FA. Cows fed WS tended to present a higher concentration of UFA in milk when compared with those fed CSFA. This study suggests that under some circumstances, abomasal flow of UFA in early lactation cows can be increased by supplementing their diet with fat supplements rich in linoleic acid, regardless of rumen protection, with small effects on ruminal DM digestibility.

    更新日期:2018-07-14
  • Effect of dietary supplements of biotin, intramuscular injections of vitamin B12, or both on postpartum lactation performance in multiparous dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-13
    D.M. Wang, B.X. Zhang, J.K. Wang, H.Y. Liu, J.X. Liu

    The current study was conducted to investigate the effects of dietary supplementation of biotin, intramuscular injections of vitamin B12 (VB12), or both beginning at the prepartum period on feed intake and lactation performance in postpartum dairy cows. Forty-eight dairy cows were allocated into 12 blocks, based on parity and milk yield of the previous lactation cycle, and randomly assigned to 1 of 4 treatments. Supplementation of VB12 (weekly intramuscular injections of 0 or 10 mg) and biotin (dietary supplements of 0 or 30 mg/d) were used in a 2 × 2 factorial arrangement in a randomized complete block design of 12 blocks with repeated measures. The study started at 3 wk before the expected calving date and ended at 8 wk after calving. Feed intake and lactation performance (milk yield and composition) were recorded weekly after calving. Blood variables were measured on d −10, 0, 8, 15, 29, 43, and 57 relative to calving. When VB12 was given, the cows had greater feed intake, better lactation performance and lower body weight loss in the postpartum period compared with animals without injection of VB12. The VB12-injected cows had lower plasma nonesterified fatty acids and β-hydroxybutyrate concentrations but higher plasma superoxide dismutase activity compared with cows without VB12. Cows fed a biotin supplement had higher milk protein yield (6 and 8 wk) and lactose yield (6–8 wk), compared with animals without biotin. However, under the present experimental conditions, we found no additive effect of a combined supplement of biotin and vitamin B12 on lactation performance of dairy cows.

    更新日期:2018-07-14
  • Evaluation of applying statistical process control techniques to daily average feeding behaviors to detect disease in automatically fed group-housed preweaned dairy calves
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-13
    W.A. Knauer, S.M. Godden, A. Dietrich, D.M. Hawkins, R.E. James

    Group housing and computerized feeding of preweaned dairy calves are gaining in popularity among dairy producers, yet disease detection remains a challenge for this management system. The aim of this study was to investigate the application of statistical process control charting techniques to daily average feeding behavior to predict and detect illness and to describe the diagnostic test characteristics of using this technique to find a sick calf compared with detection by calf personnel. This prospective cross-sectional study was conducted on 10 farms in Minnesota (n = 4) and Virginia (n = 6) utilizing group housing and computerized feeding from February until October 2014. Calves were enrolled upon entrance to the group pen. Calf personnel recorded morbidity and mortality events. Farms were visited either every week (MN) or every other week (VA) to collect calf enrollment data, computer-derived feeding behavior data, and calf personnel–recorded calf morbidity and mortality. Standardized self-starting cumulative sum (CUSUM) charts were generated for each calf for each daily average feeding behavior, including drinking speed (mL/min), milk consumption (L/d), and visits to the feeder without a milk meal (no.). A testing subset of 352 calves (176 treated, 176 healthy) was first used to find CUSUM chart parameters that provided the highest diagnostic test sensitivity and best signal timing, which were then applied to all calves (n = 1,052). Generalized estimating equations were used to estimate the diagnostic test characteristics of a single negative mean CUSUM chart signal to detect a sick calf for a single feeding behavior. Combinations of feeding behavior signals were also explored. Single signals and combinations of signals that included drinking speed provided the most sensitive and timely signal, finding a sick calf up to an average (±SE) of 3.1 ± 8.8 d before calf personnel. However, there was no clear advantage to using CUSUM charting over calf observation for any one feeding behavior or combination of feeding behaviors when predictive values were considered. The results of this study suggest that, for the feeding behaviors monitored, the use of CUSUM control charts does not provide sufficient sensitivity or predictive values to detect a sick calf in a timely manner compared with calf personnel. This approach to examining daily average feeding behaviors cannot take the place of careful daily observation.

    更新日期:2018-07-14
  • Microbial analysis of commercially available US Queso Fresco
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-13
    Maxwell J. Holle, Luis A. Ibarra-Sánchez, Xiaoji Liu, Matthew J. Stasiewicz, Michael J. Miller

    Queso Fresco (QF), a fresh Hispanic-style cheese, is often associated with Listeria monocytogenes outbreaks and recalls. Queso Fresco's susceptibility to bacterial contamination is partially due to its high pH and moisture content as well as Listeria's tolerance for the salt content typical for QF. Nine different brands of US QF, 2 packages from 4 different lots (to account for temporal variability), were sampled. The pH, salt content, and moisture content were analyzed in addition to microbial testing including yeasts and molds, coliforms, lactic acid bacteria enumeration, and L. monocytogenes counts. The cheeses were also inoculated with a cocktail of 5 food and human isolates of food-borne outbreak-associated Listeria monocytogenes strains to evaluate how the differences between brands influenced Listeria growth. Three of the cheeses underwent additional genus-level microbial analysis using extracted 16S rDNA, allowing for phylogenetic analysis between bacterial taxa including diversity and relative abundance. We found little variation between the sampled QF pH (range = 6.62–6.86), salt content (1.53–2.01%), and moisture content (43.90–54.50%). Yeasts and molds were below the detection limit of enumeration in all of the cheeses and coliforms were below the detection limit across the first 3 lots, but were detected at varying levels in the fourth lot (>3.0 most probable number/g) for 3 of the brands. Listeria monocytogenes was not isolated after enrichment in any of the samples. All cheeses tested positive for the presence of lactic acid bacteria, with only 1 of the cheeses being labeled as produced with added cultures having substantial counts. Fourteen days after inoculation with L. monocytogenes, at least 2.5 log10 cfu/g of growth was found for all QF brands stored at 4°C. Microbial genus analysis showed that, among the 3 brands, the microbial community was more similar within brand than when compared with the other 2 brands. Thermus, Anoxybacillus, and Streptococcus accounted for the dominant genera of brands A, B, and C, respectively. These variations within the microbial community may account for sensory differences and help manufacturers determine quality control consistency more readily than culture-based methods.

    更新日期:2018-07-14
  • A national methodology to quantify the diet of grazing dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    D. O'Brien, B. Moran, L. Shalloo

    The unique rumen of dairy cows allows them to digest fibrous forages and feedstuffs. Surprisingly, to date few attempts have been made to develop national methods to gain an understanding on the make-up of a dairy cow's diet, despite the importance of milk production. Consumer interest is growing in purchasing milk based on the composition of the cows' diet and the time they spend grazing. The goal of this research was to develop such a methodology using the national farm survey of Ireland as a data source. The analysis was completed for a 3-yr period from 2013 to 2015 on a nationally representative sample of 275 to 318 dairy farms. Trained auditors carried out economic surveys on farms 3 to 4 times per annum. The auditors collected important additional information necessary to estimate the diet of cows including the length of the grazing season, monthly concentrate feeding, type of forage(s) conserved, and milk production. Annual cow intakes were calculated to meet net energy requirements for production, maintenance, activity, pregnancy, growth, and live weight change using survey data and published literature. Our analysis showed that the average annual cow feed intake on a fresh matter basis ranged from 22.7 t in 2013 to 24.8 t in 2015 and from 4.8 to 5 t on a dry matter basis for the same period. Forage, particularly pasture, was the largest component of the Irish cow diet, typically accounting for 96% of the diet on a fresh matter basis and 82% of dry matter intake over the 3 yr. Within the cows' forage diet, grazed pasture was the dominant component and on average contributed 74 to 77% to the average annual cow fresh matter diet over the period. The proportion of pasture in the annual cow diet as fed was also identified as a good indicator of the time cows spend grazing (e.g., coefficient of determination = 0.85). Monthly, forage was typically the main component of the cow diet, but the average contribution of concentrate was substantial for the early spring months of January and February (30 to 35% of dry matter intake). Grazed pasture was the dominant source of forage from March to October and usually contributed 95 to 97% of the diet as fed in the summer period. Overall, the national farm survey from 2013 to 2015 shows that Irish dairy farms are very reliant on forage, particularly pasture, regardless of whether it is reported on a dry matter basis or as fed. There is potential to replicate this methodology in any regions or nations where representative farm surveys are conducted.

    更新日期:2018-07-05
  • Use of a breeding bull and absence of a calving pen as risk factors for the presence of Mycoplasma bovis in dairy herds
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    Linde Gille, J. Callens, K. Supré, F. Boyen, F. Haesebrouck, L. Van Driessche, K. van Leenen, P. Deprez, B. Pardon

    Mycoplasma bovis is an important cause of pneumonia and mastitis in cattle throughout the world, often reported as emerging. In absence of an effective vaccine for M. bovis, current prevention and control strategies rely on the identification of risk factors for within- and between-herd spread. The objective of this study was to determine the prevalence of M. bovis in Belgian dairy herds and to identify risk factors associated with a positive PCR or antibody ELISA bulk tank milk (BTM) test. A cross-sectional study was performed in 2016 on 100 dairy farms, analyzing BTM using PCR and antibody ELISA. Information on herd-level risk factors focusing on biosecurity and management were collected through a questionnaire and sourced from the national herd identification system (SANITRACE, Animal Health Service Flanders). Multivariable logistic regression was used to identify herd-level risk factors for the presence of M. bovis DNA and antibodies in BTM. The apparent prevalence on BTM was 7 and 17% for PCR and antibody ELISA, respectively. The true prevalence was 7.1% [95% confidence interval (CI) = 2.1–11.5%] and 24.8% (95% CI = 16.4–33.2%). There was no overlap between ELISA- and PCR-positive farms, resulting in a combined true prevalence of 31.8% of the Belgian farms being in recent contact with M. bovis. Risk factor analysis showed that herds with a breeding bull [M. bovis-positive results for 45.5 and 13.6% of herds with and without a bull, respectively, odds ratio = 4.7 (95% CI = 1.1–19.8)] and without a calving pen [M. bovis-positive result in 52.4 and 20.6% of the herds without and with a calving pen, respectively, odds ratio = 3.7 (95% CI = 1.06–12.5)] had higher odds to harbor M. bovis antigen or antibodies in BTM. In conclusion, the present study points to a several fold increase in the prevalence of M. bovis in Belgian dairy herds. The importance of the breeding bull and calving pen in the between- and within-herd spread of M. bovis might have been underestimated in the past. Focusing on these factors might contribute to more effective control programs in the future.

    更新日期:2018-07-05
  • Influence of milk yield on profitability—A quantile regression analysis
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    Anke Schorr, Markus Lips

    This paper analyzes the factors that influence the economic success of Swiss dairy farms, as measured by the annual income per family work unit, using panel data regression techniques. Based on more than 5,400 farm-year observations, the main focus of the analysis concerns the milk yield per cow and year as the key explanatory variable, which can be adjusted by the farm manager in the medium term. We apply both a random effects model and a quantile regression based on deciles, which allows us to study the heterogeneity of the sample in greater detail. Consistent with the current literature, the random effects model shows the positive contribution of the milk yield, namely an additional 1,000 kg/cow results in an increase of CHF 2,660; that is, 6% of the annual income. The quantile regression reveals that the effect of the milk yield differs between deciles, with a high milk yield being most beneficial for the best-performing farms, accounting for up to CHF 7,210 per 1,000 kg. Our analysis further shows the influence of the milk yield on profitability to be highly heterogeneous among Swiss dairy farms, indicating business-specific extension services and not suggesting the requirement for an increased milk yield at each level of economic success.

    更新日期:2018-07-05
  • Effect of ammonia fiber expansion on the available energy content of wheat straw fed to lactating cattle and buffalo in India
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    Preeti Mor, Bryan Bals, Amrish Kumar Tyagi, Farzaneh Teymouri, Nitin Tyagi, Sachin Kumar, Venkataraman Bringi, Michael VandeHaar

    The seasonal lack of availability of lush green forages can force dairy farmers in developing nations to rely on crop residues such as wheat and rice straw as the major feed source. We tested whether ammonia fiber expansion (AFEX) treatment of wheat straw would increase the energy available to Murrah buffalo and Karan-Fries cattle consuming 70% of their diet as wheat straw in India. Forty lactating animals of each species were blocked by parity and days in milk and randomly assigned to 1 of 4 treatment diets (n = 10). Treatments were a nutrient-rich diet with 0 to 20% straw (positive control; PC) and 3 high-straw diets with various levels of AFEX-treatment: (1) 70% untreated straw (no AFEX), (2) 40 to 45% untreated straw with 25 to 30% AFEX-treated straw (low AFEX), and (3) 20% untreated straw with 50% AFEX-treated straw (high AFEX). The AFEX-treated straw was pelleted. Urea was added to the no and low AFEX diets so they were isonitrogenous with the high AFEX diet. Animals were individually fed the PC diet for 14 d followed by 7 d of adaptation to treatments, full treatments for 28 to 35 d, and finally PC diets for 21 d. Compared with buffalo fed the PC diet, those fed high-straw diets consumed 29% less feed dry matter, put out 16% less milk energy, and lost 0.8 kg/d more body weight; the AFEX treatment of straw did not alter intake or milk production but greatly ameliorated the body weight loss (−1.0 kg/d for no AFEX and −0.07 kg/d for high AFEX). In Karan-Fries cattle, high-straw diets decreased dry matter intake by 39% and milk energy by 24%, and the high AFEX diet increased intake by 42% and milk energy by 18%. The AFEX treatment increased digestibilities of organic matter, dry matter, neutral detergent fiber, acid detergent fiber, and crude protein by 6 to 13 percentage points in buffalo and 5 to 10 points in cattle. In conclusion, AFEX treatment increased the digestibility and energy availability of wheat straw for lactating buffalo and cattle and has commercial potential to improve milk production and feed efficiency when high-quality forages or grains are not available.

    更新日期:2018-07-05
  • A survey of United States dairy hoof care professionals on costs associated with treatment of foot disorders
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    K.A. Dolecheck, R.M. Dwyer, M.W. Overton, J.M. Bewley

    The objective of this study was to collect information regarding hoof care professionals' billing practices and to gather their opinions about foot disorders and the value of their prevention. Responses were gathered from veterinarians (n = 18) and hoof trimmers (n = 116) through both online and paper survey platforms. Because of the limited number of respondents, veterinarian responses were not further analyzed. Of the 6 foot disorders included in the survey, the treatment cost per case was greatest for toe ulcers (mean ± standard deviation; $20.2 ± 8.5), sole ulcers ($19.7 ± 8.6), white line disease ($19.5 ± 8.1), and thin soles ($18.1 ± 8.1), and least for infectious disorders (foot rot and digital dermatitis; $8.0 ± 7.6 and $7.5 ± 9.6, respectively). Of the disorders, digital dermatitis represented most of the foot disorder cases treated by respondents over the past year (43.9 ± 20.4%), whereas toe ulcers and thin soles represented the least (5.3 ± 4.1 and 5.3 ± 5.7%, respectively). Respondents that served mostly large herds (>500 lactating cows) reported a lower prevalence of digital dermatitis (31.6 ± 4.2 vs. 44.4 ± 3.4 and 46.7 ± 3.2% in small and medium herds, respectively) and a higher prevalence of sole ulcers (23.1 ± 3.0 vs. 13.4 ± 2.4 and 13.3 ± 2.3% in small and medium herds, respectively). Region of the United States (Northeast, Midwest, or other) also influenced foot disorder prevalence; respondents from the Northeast reported more sole ulcers than respondents from other regions (22.1 ± 2.3 vs. 12.4 ± 3.3%). When respondents were asked which disorder was associated with the greatest total cost per case to the producer (treatment and labor costs plus the reduction in milk yield, reduced reproductive performance, and so on), hoof trimmers ranked digital dermatitis as having the greatest total cost per case and thin soles as having the least total cost per case. Finally, respondents indicated that the most important benefits of reducing foot disorders were enhanced animal welfare and increased milk production, whereas the least important benefit was reduced veterinary and hoof trimmer fees. Results from this survey can be used to improve the accuracy of foot disorder cost estimates and contribute to better decision-making regarding both foot disorder treatment and prevention.

    更新日期:2018-07-05
  • Cheese yield, cheesemaking efficiency, and daily production of 6 breeds of goats
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    Giuseppe M. Vacca, Giorgia Stocco, Maria L. Dettori, Andrea Summer, Claudio Cipolat-Gotet, Giovanni Bittante, Michele Pazzola

    Little is known about the complex process of cheesemaking at the individual level of dairy goats because of the difficulties of producing a high number of model cheeses. The objectives of this work were (1) to study the cheesemaking ability of goat milk; (2) to investigate the variability of cheesemaking-related traits among different farms; (3) to assess the effects of stage of lactation and parity; and (4) to compare 6 breeds of goat (Saanen and Camosciata delle Alpi for the Alpine type; Murciano-Granadina, Maltese, Sarda and Sarda Primitiva for the Mediterranean type) for their cheesemaking ability. For each goat (n = 560) we studied (1) 8 milk quality traits (fat, protein, total solids, casein, lactose, pH, somatic cell score, and bacterial count); (2) 4 milk nutrient recovery traits (fat, protein, total solids, and energy) in curd; (3) 3 actual cheese yield traits (fresh cheese, cheese solids, and cheese water); (4) 2 theoretical cheese yield values (fresh cheese and cheese solids) and the related cheesemaking efficiencies; and (5) daily milk yield and 3 daily cheese yield traits (fresh cheese, cheese solids, and water retained in the curd). With respect to individual animal factors, farm was not particularly important for recovery traits or actual and theoretical cheese yield and estimates of efficiency, whereas it highly influenced daily productions. Parity of goats influenced daily cheese production, whereas DIM slightly affected recovery as well as percent and daily cheese yield traits. Breed was the most important source of variation for almost all cheesemaking traits. Compared with those of Alpine type, the 4 Mediterranean breeds had, on average, lower daily milk and cheese productions, greater actual and theoretical cheese yield, and higher recovery of nutrients in the curd. Among Alpine type, Camosciata delle Alpi was characterized by greater nutrients recovery than Saanen. Within the 4 Mediterranean types, the 3 Italians produced much less milk per day, with much more fat and protein and greater recovery traits than the Murciano-Granadina, resulting in greater actual cheese yield. Within the Italian breeds, milk from Sarda and Sarda Primitiva was characterized by lower daily yields, higher protein and fat content, and greater recoveries of nutrients than Maltese goats. These results confirmed the potential of goat milk for cheese production and could be useful to give new possibilities and direction in breeding programs.

    更新日期:2018-07-05
  • Multidrug residues and antimicrobial resistance patterns in waste milk from dairy farms in Central California
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    P.N. Tempini, S.S. Aly, B.M. Karle, R.V. Pereira

    Waste milk (WM) is a common source of feed for preweaned calves in US dairy farms. However, limited information is available about characteristics of this product, including concentration of drug residues and potential hazards from antibiotic-resistant bacteria present in the milk. The aims of this cross-sectional study were to (1) identify and measure the concentration of antimicrobial residues in raw WM samples on dairy farms in the Central Valley of California, (2) survey farm management practices for factors associated with the occurrence of specific antimicrobial residues in raw WM, (3) characterize the antimicrobial resistance patterns of E. coli cultured from raw WM samples, and (4) evaluate the potential association between WM quality parameter and risk of identifying drug residues in milk. A single raw bulk tank WM sample was collected from dairy farms located in California's Central Valley (n = 25). A questionnaire was used to collect information about farm management practices. Waste milk samples were analyzed for a multidrug residue panel using liquid chromatography–tandem mass spectrometry. Bacteria were cultured and antimicrobial resistance was tested using standard techniques; milk quality parameters (fat, protein, lactose, solids-not-fat, somatic cell count, coliform count, and standard plate count) were also measured. Of the 25 samples collected, 15 (60%) contained detectable concentrations of at least 1 antimicrobial. Of the drug residue–positive samples, 44% (11/25) and 16% (4/25) had detectable concentrations of β-lactams and tetracycline, respectively. The most prevalent drug residues were ceftiofur (n = 7, 28%), oxytetracycline (n = 4, 16%), and cephapirin (n = 3, 12%). No significant associations were identified between farm characteristics or management practices and presence of drug residues in WM. In this study, 20% of farms did not pasteurize WM before feeding to calves. Two of the 10 Escherichia coli isolated from WM samples were multidrug resistant. Streptococcus spp. (n = 21, 84%) was the most common genus cultured from WM samples, followed by Staphylococcus spp. (n = 20, 80%) and E. coli (n = 10, 40%). Mycoplasma spp. was cultured from 2 WM samples (n = 2, 8%). The presence of drug residues in WM at concentrations that increase selection of resistant bacteria indicates the need for additional studies targeting on-farm milk treatments to degrade drug residues before feeding to calves. The presence of multidrug-resistant E. coli in WM urges the need for on-farm practices that reduce calf exposure to resistant bacteria, such as pasteurization.

    更新日期:2018-07-05
  • Environmental sample characteristics and herd size associated with decreased herd-level prevalence of Mycobacterium avium subspecies paratuberculosis
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    Caroline S. Corbett, S. Ali Naqvi, Jeroen De Buck, Uliana Kanevets, John P. Kastelic, Herman W. Barkema

    Environmental sampling is an effective method for estimating regional dairy herd-level prevalence of infection with Mycobacterium avium ssp. paratuberculosis (MAP). However, factors affecting prevalence estimates based on environmental samples are not known. The objective was to determine whether odds of environmental samples collected on farm changed culture status over 2 sampling times and if changes were specific for location and type of housing (freestall, tiestall, or loose housing), the sample collected (i.e., manure of lactating, dry, or sick cows; namely, cow group), and effects of herd size. In 2012–2013 [sampling 1 (S1)] and 2015–2017 [sampling 2 (S2)], 6 environmental samples were collected and cultured for MAP from all 167 (99%) and 160 (95%) farms, respectively, in the province of Saskatchewan, Canada. Only the 148 dairy farms sampled at both sampling periods were included in the analysis. A mixed effects logistic regression was used to determine whether differences between sampling periods were associated with herd size and sample characteristics (cow group contributing to environmental sample, type of housing, and location). In S1 and S2, 55 and 34%, respectively, of farms had at least 1 MAP-positive environmental sample. Correcting for sensitivity of environmental sampling, estimated true prevalence in S1 and S2 was 79 and 48%, respectively. Herds with >200 cows were more often MAP-positive than herds with <51 cows in both S1 and S2. The percentage of positive samples was lower in S2 compared with S1 for all sampled areas, cow groups contributing to samples, types of housing where samples were collected, and herd size categories. However, samples collected from dry cow areas had the largest decrease in MAP-positive samples in S2 compared with all other cow group samples. Herds that were MAP-negative in S1 with a herd size 51 to 100 or 101 to 150 were more likely to stay MAP-negative, whereas MAP-positive herds with >200 cows more frequently stayed MAP-positive. No difference was observed in the odds of a sample being MAP-positive among housing types or location of sample collection in both sample periods. Of all farms sampled, 104 (70%) did not change status from S1 to S2. In conclusion, when herd-level MAP prevalence decreased over the 3-yr interval, the change in prevalence differed among herd size categories and was larger in samples from dry cow areas. It was, however, not specific to other characteristics of environmental samples collected.

    更新日期:2018-07-05
  • Investigation of ammonium lactate supplementation on fermentation end products and bacterial assimilation of nitrogen in dual-flow continuous culture
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    B.K. Wagner, B.A. Wenner, J.E. Plank, G.D. Poppy, J.L. Firkins

    Supplements investigated throughout the present study are produced by fermenting lactose that is present in whey to lactate, yielding products differing in ammonium relative to lactate concentrations and in physical form (liquid or dry). Trials 1 and 2 investigated Lacto-Whey (LW; Fermented Nutrition Corp., Luxemburg, WI) and GlucoBoost (GB; Fermented Nutrition Corp.), respectively, using dual-flow continuous culture systems (n = 4), each with a 4 × 4 Latin square design. A greater proportion of nonprotein nitrogen was present in GB than in LW. In trial 1, the treatment with LW was isonitrogenously dosed against soybean meal (SBM) as a control (no LW) and factorialized with either a wheat- or corn-based concentrate (55% inclusion rate, dry matter basis). We hypothesized that LW would increase propionate production and that the combination of +LW with wheat would increase bacterial assimilation of NH3-N into cellular N. No differences were observed for total volatile fatty acid (VFA) production per day. However, treatment × time interactions revealed that +LW increased lactate concentration at 0, 0.5, and 1 h and tended to increase molar percentage of propionate at 1 and 1.5 h postfeeding, documenting the immediate availability of lactate converted to propionate in the +LW treatments. The main effect of corn increased the proportion of bacterial N derived from NH3-N. Trial 2 was designed to investigate GB; isonitrogenous treatments included an SBM control, crystal GB, liquid GB (LGB), and LGB with yeast culture, which were dosed twice daily. We hypothesized that GB would increase propionate production and bacterial assimilation of NH3-N; the combination of LGB and yeast culture was expected to have a positive additive effect, yielding the greatest VFA production and bacterial NH3-N assimilation. No differences were observed for total VFA production; however, LGB decreased molar percentage of acetate and increased propionate and butyrate molar percentages. There were no differences in non-NH3-N flow or microbial N flow. Under the conditions of our studies, lactate in LW and GB was fermented extensively to propionate, and microbial protein synthesis in these treatments was comparable with that in SBM controls.

    更新日期:2018-07-05
  • Randomized prospective trials to study effects of reduced antibiotic usage in abdominal surgery in cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    R. Jorritsma, I.M. van Geijlswijk, M. Nielen

    Societal concerns about antibiotic resistance prompted us to evaluate the use of prophylactic and postoperative antibiotic treatments following cesarean section (CS) and exploratory laparotomy (EL) in a surgery theater within the Farm Animal Health clinic. All procedures were performed by supervised veterinary students for training purposes. Cows undergoing CS (n = 100) received either a prophylaxis with a single 5-g injection of ampicillin-sodium i.v. only (CSL), or in combination with postoperative i.m. injections of ampicillin-trihydrate 20% for 3 d (10 mg/kg, twice a day; CSH). Cows undergoing EL (n = 110) received either no antibiotic prophylaxis (ELN) or were given a single 5-g injection of ampicillin-sodium i.v. (ELL). The primary outcome measure was healthy recovery after surgery, which we assessed according to the need to treat surgery-related complications within a 10-d follow-up period based on daily clinical observations. Cows in all groups had a normal temperature and feed intake, and a satisfying clinical appearance at the end of the follow-up period. The clinical need to treat cows with antibiotics to deal with postoperative complications was higher for the CS groups than the EL groups. Within both CS and EL groups, the number of complications for each protocol was the same. However, in terms of the secondary outcomes, we observed that CSL cows required, for example, more treatments for mastitis and other diseases unrelated to the surgery than CSH cows (odds ratio 2.8; confidence interval 1.2–7.2). The percentage of infected sutures was higher for ELN cows compared with ELL cows (odds ratio 2.6; confidence interval 1.5–4.9). We estimated that 29 CSH treatments were needed to prevent 1 CS cow with serious surgery-related complications in the CSL group. Likewise, 53 ELL treatments would prevent 1 EL cow with surgery-related complications in the ELN group. We therefore concluded that it is possible to reduce antibiotic prophylaxis in CS and EL cows. The low number cows of clinically detected complications were effectively treated with a postoperative antibiotic intervention at the moment of detection.

    更新日期:2018-07-05
  • A randomized clinical trial of topical treatments for mild and severe udder cleft dermatitis in Dutch dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-07-04
    T. van Werven, J. Wilmink, S. Sietsma, J. van den Broek, M. Nielen

    Udder cleft dermatitis (UCD) is a skin lesion in dairy cows affecting the anterior parts of the udder, with the lesions often needing a long time to heal. The lesions can be characterized as mild or severe. The etiology of UCD is not fully understood and studies on the effectiveness of topical treatments have not been published. The objective of this study, therefore, was to conduct a randomized clinical trial to investigate the effectiveness of 2 different topical treatments, one for mild and one for severe UCD lesions, compared with untreated control groups. The treatment and control groups were randomized within herd for mild and severe UCD. The treatments were applied for a maximum period of 12 wk on 8 Dutch dairy farms. Mild UCD lesions were treated once a d 3 times a week on fixed days with a non-sting barrier film. Severe UCD lesions were first stratified into class A (lesion length <5 cm) or class B (lesion length ≥5 cm) and then randomly allocated to treatment or control groups within herd. Both severe lesion classes were treated once per day every day with an enzyme alginogel. Every week, the lesions of affected animals were inspected and photographed by the investigator. These photographs were reviewed weekly by an external wound expert who classified the lesions as mild, severe class A, severe class B, or healed. Based on this classification, the investigator judged weekly whether the lesions had improved compared with their classification of the previous week. For mild UCD lesions, improvement was defined as occurring when lesions were healed. For severe UCD lesions, improvement was defined as a transition from class B to class A, transition from any severe UCD lesion (class A or B) to a mild UCD lesion, or when the lesion was defined as healed. Data were analyzed using a discrete time survival analysis with time to first improvement as dependent variable. In total, data from 214 animals were analyzed to estimate the effectiveness of treatment. Results showed that treatment of mild UCD lesions had no influence on improvement compared with untreated lesions. Treated severe lesions, however, showed 3.4 times more improvement compared with the untreated controls. Improvement varied between herds, and cows with a parity of 5 or higher showed significantly less improvement than first parity animals. Early identification of severe UCD lesions followed by prompt treatment with an enzyme alginogel supports the healing process.

    更新日期:2018-07-05
  • Effect of dietary cation-anion difference on acid-base status and dry matter intake in dry pregnant cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-30
    R. Zimpel, M.B. Poindexter, A. Vieira-Neto, E. Block, C.D. Nelson, C.R. Staples, W.W. Thatcher, J.E.P. Santos

    The objective was to determine if the reduction in dry matter (DM) intake of acidogenic diets is mediated by inclusion of acidogenic products, content of salts containing Cl, or changes in acid-base status. The hypothesis was that a decrease in intake is mediated by metabolic acidosis. Ten primigravid Holstein cows at 148 ± 8 d of gestation were used in a duplicated 5 × 5 Latin square design. The dietary cation-anion difference (DCAD) of diets and acid-base status of cows were manipulated by incorporating an acidogenic product or by adding salts containing Cl, Na, and K to the diets. Treatments were a base diet (T1; 1.42% K, 0.04% Na, 0.26% Cl; DCAD = 196 mEq/kg); the base diet with added 1% NaCl and 1% KCl (T2; 1.83% K, 0.42% Na, 1.23% Cl; DCAD = 194 mEq/kg); the base diet with added 7.5% acidogenic product, 1.5% NaHCO3, and 1% K2CO3 (T3; 1.71% K, 0.54% Na, 0.89% Cl; DCAD = 192 mEq/kg); the base diet with added 7.5% acidogenic product (T4; 1.29% K, 0.13% Na, 0.91% Cl; DCAD = −114 mEq/kg); and the base diet with 7.5% acidogenic product, 1% NaCl, and 1% KCl (T5; 1.78% K, 0.53% Na, 2.03% Cl; DCAD = −113 mEq/kg). Periods lasted 14 d with the last 7 d used for data collection. Feeding behavior was evaluated for 12 h in the last 2 d of each period. Reducing the DCAD by feeding an acidogenic product reduced blood pH (T1 = 7.450 vs. T2 = 7.436 vs. T3 = 7.435 vs. T4 = 7.420 vs. T5 = 7.416) and induced a compensated metabolic acidosis with a reduction in bicarbonate, base excess, and partial pressure of CO2 in blood, and reduced pH and strong ion difference in urine. Reducing the DCAD reduced DM intake 0.6 kg/d (T1 = 10.3 vs. T4 = 9.7 kg/d), which was caused by the change in acid-base status (T2 + T3 = 10.2 vs. T4 + T5 = 9.6 kg/d) because counteracting the acidifying action of the acidogenic product by adding salts with strong cations to the diet prevented the decline in intake. The decline in intake caused by metabolic acidosis also was observed when adjusted for body weight (T2 + T3 = 1.75 vs. T4 + T5 = 1.66% BW). Altering the acid-base status with acidogenic diets reduced eating (T2 + T3 = 6.7 vs. T4 + T5 = 5.9 bouts/12 h) and chewing (T2 + T3 = 14.6 vs. T4 + T5 = 13.5 bouts/12 h) bouts, and extended meal duration (T2 + T3 = 19.8 vs. T4 + T5 = 22.0 min/meal) and intermeal interval (T2 + T3 = 92.0 vs. T4 + T5 = 107.7 min). Results indicate that reducing the DCAD induced a compensated metabolic acidosis and reduced DM intake, but correcting the metabolic acidosis prevented the decline in DM intake in dry cows. The decrease in DM intake in diets with negative DCAD was mediated by metabolic acidosis and not by addition of acidogenic product or salts containing Cl.

    更新日期:2018-07-01
  • Characterization and identification of surface crystals on smear-ripened cheese by polarized light microscopy
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-30
    P.J. Polowsky, G.F. Tansman, P.S. Kindstedt, J.M. Hughes

    Surface crystallization and radial demineralization of Ca, P, and Mg occur in smear-ripened cheese. Furthermore, crystals of ikaite, struvite, calcite, and brushite have been identified in cheese smears by powder x-ray diffractometry (PXRD), and ikaite and struvite exist in smears as single crystals. Polarized light microscopy (PLM) is a simple, inexpensive, and well-established method in geology to detect and identify single crystals. However, use of PLM to identify cheese crystals has not been reported previously. The specific objectives of this research were (1) to identify crystals in cheese smears using selected PLM criteria; (2) to compare identification by PLM against PXRD; and (3) to develop and evaluate a novel treatment for smear material to improve crystal analyses by both PLM and PXRD. Duplicate wheels of 4 cheeses produced by different manufacturers were obtained from retail sources. Scrapings of surface smears were prepared and analyzed by PLM and PXRD by previously described methods. Crystals were categorized by PLM based on angle of extinction (AE), birefringence behavior under crossed polarizers and quartz filters, and size and shape (circularity) by image analysis. Crystals observed by PLM fell almost exclusively into 2 readily differentiated groups based on birefringence behavior and estimated angle of extinction. Group 1 (n = 18) were highly birefringent with AE = 88–92°, whereas group 2 (n = 28) had no birefringence with AE = 13–26°. Group 2 crystals were significantly larger and more circular than group 1 crystals. Group 1 and 2 were identified as struvite and ikaite, respectively, based on known birefringence and AE characteristics. Struvite was identified in all 4 cheeses by PLM but in only 3 cheeses by PXRD. Ikaite was identified in 3 cheeses by PLM but in only 2 cheeses by PXRD. These discrepancies occurred because the smear scrapings from 1 cheese contained excessive amorphous matter that caused extreme background noise, potentially obscuring diffractogram peaks that may have been present. To minimize noise, smear scrapings were dispersed in aqueous NaOH (pH 10) before analyses, which resulted in consistent results by PXRD and PLM. The method also rendered high-quality images by PLM. Data suggest that PLM may offer a simple and inexpensive means to identify struvite, ikaite, and possibly other single crystals in cheese smears.

    更新日期:2018-07-01
  • Genetic parameters of different measures of somatic cell counts in the Rendena breed
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Nadia Guzzo, Cristina Sartori, Roberto Mantovani

    The objective of this study was to consider different and alternative methods of using somatic cell count (SCC) data recorded according to the Italian official milk recording system, estimating its genetic parameters and the correlations with the yield traits (milk, fat, and protein) in the Rendena breed. The SCC traits defined for genetic evaluation were somatic cell score, log of the total daily SCC (LTSCC, i.e., SCC multiplied by daily milk yield) individually recorded in a day of official control, and 3 different thresholds (≥80,000, ≥150,000, and ≥400,000 cells/mL) for somatic cells. A total of 187,052 test-day monthly records of milk, fat, and protein yields and SCC belonging to 11,718 cows were used to estimate heritability and genetic correlations between SCC and yield traits via a bi-trait repeatability test-day model using a Bayesian approach. The heritability values estimated for the threshold traits ranged from 0.036 to 0.065, less than those observed for monthly somatic cell score and LTSCC traits that were equivalent to 0.088 and 0.103, respectively. Higher genetic correlations were estimated between LTSCC trait and all productive traits (0.379 for milk, 0.240 for fat, and 0.370 for protein). The other SCC traits considered have shown low or almost null genetic correlations with the productive traits (from 0.008 between fat yield and SCC ≥150,000 cells/mL to 0.234 between protein yield and SCC ≥400,000 cells/mL) and almost all estimates included zero in the 95% highest posterior density region interval. These results indicated that genetic selection for milk, fat, and protein production negatively affects the LTSCC content and SCC ≥400,000 cells/mL but does not negatively influence the other somatic cell and threshold SCC traits in the Rendena breed. However, the complete framework of genetic relationships of SCC with all traits under selection should be considered when deciding on the possible inclusion of SCC in the breeding program of this small cattle population.

    更新日期:2018-06-30
  • Effects of milk replacer acidification and free-access feeding on early life feeding, oral, and lying behavior of dairy calves
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    C.G. Todd, S.T. Millman, K.E. Leslie, N.G. Anderson, J.M. Sargeant, T.J. DeVries

    Acidification is a practical way of preserving the bacteriological quality of milk so that it can be fed to calves under free-access conditions. The objectives of this study were to evaluate how milk replacer acidification and free-access feeding affect dairy calf behavior during the first week of life. Sixteen Holstein male calves were purchased at birth and transported to the University of Guelph Kemptville Campus Dairy Education and Research Centre. Calves were randomly assigned to 1 of 4 milk feeding programs: (1) free-access (ad libitum) feeding of acidified milk replacer (22% crude protein and 17% fat, 150 g/L; FA); (2) restricted (6 L/d, 150 g/L) feeding of acidified milk replacer (RA); (3) free-access feeding of nonacidified milk replacer (FN); and (4) restricted feeding of nonacidified milk replacer (RN). Formic acid was used to acidify milk replacer to a target pH between 4.0 and 4.5. Video recordings of each calf at 1, 2, and 6 d were analyzed continuously over 24 h for all occurrences of each behavior in the ethogram. Feeding behavior observations were organized into sucking bouts, from which feeding behavior outcome variables were calculated. Calves consuming acidified milk replacer demonstrated more fragmented feeding patterns, characterized by more pauses within a sucking bout (FA, FN, RA, and RN calves = 12.4, 4.4, 13.7, and 11.9 pauses/bout, respectively) and longer sucking bout duration (FA, FN, RA, and RN calves = 8.8, 5.2, 9.3, and 8.1 min/bout, respectively), than calves fed nonacidified milk replacer. Restricted-fed calves tended to have longer sucking bouts and performed more within-bout sucks (FA, FN, RA, and RN calves = 10.7, 5.8, 13.5, and 14.1, respectively) and pauses than free-access calves. Acidification and free-access feeding did not affect lying duration. Calves assigned to the acidified feeding treatments tended to perform more grooming behavior than those fed nonacidified milk replacer (FA, FN, RA, and RN calves = 0.9, 0.5, 0.8, and 0.6 h/d, respectively). Free-access feeding did not affect grooming duration. The observed differences in feeding and grooming behavior suggest that acidification to a pH between 4.0 and 4.5 may have altered the palatability of milk replacer. Calves assigned to the acidified milk replacer feeding treatments did not, however, show avoidance toward this feedstuff during the first week of life.

    更新日期:2018-06-30
  • Short communication: Comparison of growth kinetics at different temperatures of Streptococcus macedonicus and Streptococcus thermophilus strains of dairy origin
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Armin Tarrah, Valentina Noal, Laura Treu, Sabrina Giaretta, Vinícius da Silva Duarte, Viviana Corich, Alessio Giacomini

    Within the genus Streptococcus, S. thermophilus and S. macedonicus are the 2 known species related to foods. Streptococci are widely used as starter cultures to rapidly lower milk pH. As S. macedonicus has been introduced quite recently, much less information is available on its technological potential. Because temperature is an important factor in fermented food production, we compared the growth kinetics over 24 h of 8 S. thermophilus and 7 S. macedonicus strains isolated from various dairy environments in Italy, at 4 temperatures, 30°C, 34°C, 37°C and 42°C. We used the Gompertz model to estimate the 3 main growth parameters; namely, lag phase duration (λ), maximum growth rate (µmax), and maximum cell number at the stationary phase (Nmax). Our results showed significant differences in average growth kinetics between the 2 species. Among the strains tested, 37°C appeared to be the optimal temperature for the growth of both species, particularly for S. macedonicus strains, which showed mean shorter lag phases and higher cell numbers compared with S. thermophilus. Overall, the growth curves of S. macedonicus strains were more similar to each other whereas S. thermophilus strains grew very differently. These results help to better define and compare technological characteristics of the 2 species, in view of the potential use of S. macedonicus in place of S. thermophilus in selected technological applications.

    更新日期:2018-06-30
  • Social housing influences the behavior and feed intake of dairy calves during weaning
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    M.A. Overvest, R.E. Crossley, E.K. Miller-Cushon, T.J. DeVries

    We investigated the effect of social housing on the behavioral, intake, and physiological changes that occur at weaning for dairy calves fed milk ad libitum. These changes were evaluated during the weaning (d 40 to 48 of age) and postweaning (d 49 to 56 of age) stages. Twenty male Holstein calves were fed milk replacer ad libitum and weaned gradually by dilution over 9 d starting at d 40 of age. Calves were housed in pairs (10 calves) or individually (10 calves) from birth until the beginning of the postweaning phase, when all calves were paired. Feed and water intake were monitored daily. Feeding time was video-recorded, and blood β-hydroxybutyrate concentration was measured on alternate days beginning on d 40 and ending on d 56 of age. Electronic accelerometers continuously recorded standing and lying behavior for the 17-d study. Solid feed consumption increased by more than 5-fold over the weaning phase in all calves; during this phase pair-housed calves consumed more than twice (0.96 vs. 0.50 kg/d on d 48) that of the individually housed calves. Postweaning all calves rapidly increased their solid feed intake, and to a greater extent for previously individually housed calves, such that intake was similar between treatments by d 56. Free water intake was stable during weaning; however, a decrease (of 6.6 L) occurred in the constituent milk replacer water intake across this phase. As result, total water intake (free water + milk replacer water content) decreased (by 6.0 L) over the weaning phase between d 40 (14.9 L/d) and d 48 (8.9 L/d). On the first day postweaning (d 49), total water intake for all calves increased sharply (to 19.0 L/d) and then returned to a lower baseline (13.2 L/d) the next day (d 50), and slowly increased over the following week. During the weaning phase, feeding time and feeding rate increased with time for all calves, whereas pair-housed calves had greater feeding rates than individually housed calves (13.4 vs. 6.6 g of DM/min). After weaning, calves previously housed individually spent more time feeding in the early hours of the day than calves housed in pairs. Lying time and lying bout frequency decreased with calf age during the weaning period across treatments, and pair-housed calves tended to spend less time lying than individually housed calves (1,015 vs. 1,039 min/d) during this time period. Blood β-hydroxybutyrate increased across treatments over the weaning period, with the largest increase occurring between d 48 (0.05 mmol/L) and d 50 (0.2 mmol/L). These results show that calves alter their behavioral patterns during weaning and that housing calves in pairs may ease the transition from milk to solid feed.

    更新日期:2018-06-30
  • Effect of fibrolytic enzymes on lactational performance, feeding behavior, and digestibility in high-producing dairy cows fed a barley silage–based diet
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Basim Refat, David A. Christensen, John J. McKinnon, Wenzhu Yang, Aaron D. Beattie, Tim A. McAllister, Jong-Su Eun, Gamal Ali Abdel-Rahman, Peiqiang Yu

    The objectives of this study were to evaluate the effects of pretreating dairy cow rations with a fibrolytic enzyme derived from Trichoderma reesei (FETR; mixture of xylanase and cellulase; AB Vista, Wiltshire, UK) on lactation performance, digestibility, and feeding behavior in response to feeding a barley silage–based diet. Before starting the dairy trial, in vitro incubations were conducted to determine whether the addition of FETR would have an effect on these animal performance characteristics when applied to a barley silage–based diet for dairy cows. The dairy trial was performed using 8 Holstein dairy cows. The cows were blocked by parity and assigned randomly to 1 of 4 treatments: 0, 0.5, 0.75, and 1 mL of FETR/kg of dry matter (DM) diet in a replicated Latin square design. The pretreatment was applied to the complete diet during the mixing process. The experimental period continued for 22 d, with each experimental period consisting of a 16-d adaptation period and a 6-d sampling period. The daily feed intake of each individual cow was monitored using Insentec feed bins (RIC system, Insentec, Marknesse, the Netherlands). Feeding behavior characteristics were measured during the entire sampling period using the feed bin attendance data. Milk samples were collected in the last 3 d of each experimental period. The addition of FETR linearly increased the in vitro DM digestibility and tended to improve the in vitro digestibility of barley silage. There was a cubic effect of the enzyme levels on the total-tract DM and neutral detergent fiber digestibility. Maximal digestibility was reached at 0.75 mL of FETR/kg of TMR. The milk fat yield, fat-corrected milk, and energy-corrected milk quadratically responded to the incremental levels of FETR. The milk protein percentage linearly improved in response to FETR. Increasing FETR levels resulted in a quadratic effect on feed efficiency. There was no effect of FETR level on feeding behavior. In conclusion, pretreating dairy cow barley silage–based diet with 0.75 mL of FETR/kg of TMR increased the milk production efficiency of dairy cows fed diet containing 34% barley silage (DM basis). The positive effect of adding FETR could benefit the dairy industry in western Canada, where barley silage–based diets are common.

    更新日期:2018-06-30
  • Pegbovigrastim treatment affects gene expression in neutrophils of pasture-fed, periparturient cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    A. Heiser, S.J. LeBlanc, S. McDougall

    Treatment with granulocyte colony-stimulating factor has been reported to increase circulating neutrophil count and enhance neutrophil function in the periparturient cow. It was hypothesized that a commercially available recombinant bovine granulocyte colony-stimulating factor product (pegbovigrastim) affects gene expression profiles of neutrophils and supports neutrophil function in periparturient cows. Hence this study was undertaken to analyze expression of genes involved in neutrophil functions, including migration, interaction with pathogens, and cell survival. It also assessed the hypothesis that gene expression profiles in neutrophils are modulated by negative energy balance in the peripartum period. Holstein-Friesian, Jersey, and mixed-breed cows on pasture were blocked by expected calving date and body condition score and randomly assigned in a 2 × 2 factorial design. Cows were fed to exceed energy requirements prepartum (122%) or restricted to approximately 85% of prepartum energy requirements. At approximately 7 d before expected calving date, half the cows in each feed group were randomly assigned to be injected with pegbovigrastim or saline. Treatments were repeated within 24 h after calving. Blood samples were collected pretreatment approximately 7 d (d −7) before calving. Blood, uterine flush, and milk samples were collected at 4 (d 4) and 7 d in milk (d 7) to measure the expression of a panel of 20 genes representing cell adhesion, pattern recognition, inflammation and cytokine response, antimicrobial capacity, and apoptosis functions in neutrophils using NanoString technology (NanoString Technologies Inc., Seattle, WA) to quantify RNA copy numbers. No effects were observed of prepartum feeding group or a feeding group × treatment interaction for any of the investigated genes. An effect was observed of time on expression of several genes in blood neutrophils. After calving, expression of 2 of 4 cell adhesion-related genes, 3 of 4 pattern recognition receptors, 2 of 4 inflammatory genes, 2 antimicrobial genes, and 2 of 4 cell survival genes was significantly greater at d 4 or 7 or both compared with before calving (d −7). Expression of ICAM1, TLR2, and PTGS2 was significantly higher in blood neutrophils from animals treated with pegbovigrastim compared with untreated controls, suggesting greater migration, pattern recognition, and inflammatory response ability. Pegbovigrastim also affected RNA expression in uterine cells with ICAM1, NOD1, CLEC6A, PTGS2, MPO, DEFB5, and CATHL6 being expressed at higher levels and SELL, ITGB8, IL8RB, and IL10 at lower levels. Milk somatic cells showed a similar pattern but with fewer significant changes. In contrast to the reported decline in neutrophil function in the transition period, neutrophil gene expression was increased for many of the genes studied, an apparent attempt to compensate for reduced neutrophil function. Treatment with pegbovigrastim further increased expression of several genes involved in these processes in blood neutrophils and changed uterine cells to a phenotype with increased antimicrobial capacity, typical for neutrophils that have migrated into their target tissue.

    更新日期:2018-06-30
  • Short communication: Chronology of different sexual behaviors and motion activity during estrus in dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    H. Dobson, J. Williams, J.E. Routly, D.N. Jones, J. Cameron, A. Holman-Coates, R.F. Smith

    In studying the efficiency of a variety of methods for estrus detection in a large dairy herd, we suspected a definite sequence of estrus signs. Consequently, we observed a subset of animals continuously between 0400 and 2400 h, making a note of the precise timing and frequency of each sexual behavior. Sixteen Holstein-Friesian cows, >20 d postpartum, were equipped with motion activity-sensing neck collars and had milk progesterone profiles monitored simultaneously. The duration between the first and last observed estrus behavior was (mean ± SE) 14.0 ± 1.9 h, with a range 8.5 to 28.75 h. The duration of standing to be mounted (STBM) was 4.68 ± 1.49 h, with a range of 0.25 to 18.25 h. Sniffing the vulva of another cow occurred on average 5.5 ± 1.3 h (range = 0.25–18.25 h) before the first STBM. By ranking the first appearance of each behavior, we established that sniffing was followed by the active behaviors of mounting another cow and not accepting a mount, as well as the passive behaviors of being sniffed and STBM by another cow. Chin resting occurred before not accepting a mount and STBM. All these behaviors were observed in the reverse order after the last STBM. The mean profile of motion activity revealed an increase in motion activity with the onset of exploratory behaviors, and highest values occurred within the period of STBM. Such distinct behavioral sequences may be controlled by changes in peripheral progesterone and estradiol concentrations, as well as by subtle independent mechanisms via pheromones in differing concentrations or divergent composition.

    更新日期:2018-06-30
  • Effect of cream aging temperature and agitation on butter properties
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Jiwon Lee, Silvana Martini

    Aging of cream is an important process to manage production time and to produce butter with consistent quality. The objective of this study was to evaluate the combined effect of temperature (5, 10, and 15°C) and agitation rate (0, 40, and 240 rpm) during aging of cream on the physical properties of cream and butter in a model system. Cream's solid fat content (SFC), melting behavior, and droplet size distribution were measured during and after 90 min of aging. Butter physical properties such as melting behavior, water content, and hardness were measured. The effects of agitation on SFC and droplet size are dependent on aging and churning temperature. Solid fat content increased faster at 5°C, and the maximum SFC was the highest at this temperature. An effect of agitation on SFC was observed only when cream was aged at 15°C. Agitating cream at 40 rpm increased the droplet size regardless of aging temperature. Two melting peaks, medium melting fraction (MMF) and high melting fraction (HMF), were found in cream samples aged at 5 and 10°C, but only a HMF melting peak was seen in the cream aged at 15°C. The enthalpy of MMF in the cream aged at 10°C with 40 rpm and without agitation was significantly lower than that in samples aged at 5°C regardless of agitation rate. Butter can be formed only from cream aged under certain conditions during 14.5 min of churning, which are 5°C with high agitation and 10°C regardless of agitation level. Butter produced with cream aged at 5°C with high agitation showed significantly higher MMF and total enthalpy values. However, no significant difference in enthalpy values was observed among the butter samples made from the cream aged at 10°C. Further crystallization of MMF occurred in the butter produced with cream aged at 10°C during 24 h of storage at 5°C, whereas no further crystallization occurred in the butter made with the cream aged at 5°C with high agitation. The hardest butter was obtained when cream was aged at 5°C with 240 rpm and at 10°C with 40 rpm. Softer butter was obtained when cream aged at 10°C with 240 rpm was used. This butter also had the highest water content. This study shows that butter hardness can be tailored by changing the aging conditions of the cream. Cream can be aged at higher temperature with low agitation without altering the hardness of butter. These results will help dairy producers to optimize butter making processes to obtain desired properties in the final product.

    更新日期:2018-06-30
  • Methylglyoxal: A newly detected and potentially harmful metabolite in the blood of ketotic dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Chao Li, Shaohua Dai, Jiangyi Lu, Baoyu Zhao, Jiangang Wang, Panpan Li, Zhaozhen Wu, Yingying Mu, Cuixia Feng, Qiang Dong

    Ketosis causes serious economic losses for the modern dairy industry because it is a highly prevalent metabolic disease among cows in high-producing herds during the transition period. Due to some striking similarities between diabetes in humans and ketosis in dairy cows, there is potential for the use of methylglyoxal (MGO)—commonly used in human diabetics—as a biomarker in dairy cattle. However, currently no data are available about the presence of MGO in the serum of dairy cattle or about the characteristics of its production or its potential contribution in the pathogenesis of ketosis. To determine the potential origin and pathway of formation of MGO, cows in different metabolic conditions [i.e., non-subclinically ketotic dairy cows in early lactation (n = 7), subclinically ketotic dairy cows in early lactation (n = 8), overconditioned dry cows (BCS >4.25, n = 6), and nonlactating heifers (n = 6)] were selected. Serum MGO concentrations were determined and correlated with indicators of the glucose and lipid metabolism and with haptoglobin (Hp) as an inflammatory marker. The serum MGO concentrations in subclinically ketotic cows (712.60 ± 278.77 nmol/L) were significantly greater than in nonlactating heifers (113.35 ± 38.90 nmol/L), overconditioned dry cows (259.71 ± 117.97 nmol/L), and non-subclinically ketotic cows (347.83 ± 63.56 nmol/L). In serum of lactating cows, concentrations of glucose and fructosamine were lower than in heifers and were negatively correlated with MGO concentrations. Even so, concentrations of metabolic and inflammatory markers such as dihydroxyacetone phosphate, nonesterified fatty acids, β-hydroxybutyrate, acetone, and Hp were remarkably higher in subclinically ketotic cows compared with nonlactating heifers; these metabolites were also positively correlated with MGO. In human diabetics elevated MGO concentrations are stated to originate from both hyperglycemia and the enhanced lipid metabolism, whereas higher MGO concentrations in subclinically ketotic cows were not associated with hyperglycemia. Therefore, our data suggest MGO in dairy cows to be a metabolite produced from the metabolization of acetone within the lipid metabolization pathway and from the metabolization of dihydroxyacetone phosphate. Furthermore, the highly positive correlation between MGO and Hp suggests that this reactive compound might be involved in the proinflammatory state of subclinical ketosis in dairy cows. However, more research is needed to determine the potential use of MGO as a biomarker for metabolic failure in dairy cows.

    更新日期:2018-06-30
  • Adaptation of dairy cows to increasing degrees of incomplete milk removal during a single milking interval
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    A. Albaaj, P.G. Marnet, C. Hurtaud, J. Guinard-Flament

    Milk accumulation in the udder decreases milk secretion and this effect is explained as well by the effects of the quantity of milk stored in the udder as by the duration and repetition of periods of milk stasis. This experiment aimed to better understand the underlying mechanisms of decreased milk yield in response to the specific effects of the quantity of milk stored in the udder, independent from storage duration, on milk yield and composition. Sixteen Holstein cows were assigned to 4 blocks of 4 cows in a 4 × 4 Latin square design using 7-d periods, with a 4-d sampling period and a 3-d washout period. Cows were milked twice daily at approximately 0700 and 1630 h throughout the trial. Treatments consisted of 4 degrees of milk removal (100, 70, 40, and 0%) applied at one morning milking, designated M0. Effects of the quantity accumulated were studied in relation to udder distension, via measurements of the total distance between the ends of the 4 teats, and cisternal capacity, via the evaluation of cisternal area by ultrasonographic scan at 1 and 9 h after M0. The effect of the quantity accumulated was also evaluated in relation to mammary epithelium permeability by determining plasma lactose concentrations 1 h before and 4, 7, and 10 h after M0. Leaving milk in the udder at M0 decreased milk production during the M0–M1 interval in a negative curvilinear manner. As a result, M0+M1 milk yield decreased or tended to decrease significantly by −1.3, −5.3, and −12.8 kg for the 70, 40, and 0% treatments compared with the 100% treatment (41.7 ± 1.26 kg/d), respectively. Negative carry-over effects on milk yield were observed until the M3 milking only for the 40 and 0% treatments, and no differences were observed between the effects of these treatments. The total distance between teats increased significantly but to decreasing degrees during the M0–M1 interval. For the 40 and 0% treatments, cisternal area, which was increased 1 h after M0 milking, exhibited no further increase during the M0–M1 interval, suggesting cisternal distension was close to maximum. Simultaneously, lactose concentrations increased in blood plasma for only these 2 treatments, and this increase occurred earlier for the 0% treatment. It was also observed that cows presenting the earliest increases in plasma lactose concentrations during milk accumulation lost more milk in response to extended milking intervals.

    更新日期:2018-06-30
  • Milk replacer restriction during early life impairs the live body weight and progesterone patterns of ewe lambs during the replacement period
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    A. Santos, F.J. Giráldez, C. Valdés, E. Trevisi, L. Lucini, J. Frutos, S. Andrés

    Nutritional programming caused by feed restriction during the early life may counteract the profitability of the dairy sheep farm. However, most studies have been focused exclusively on the prenatal period, and scarce information regarding the effect of milk replacer (MR) restriction on feed efficiency [residual feed intake (RFI)] and progesterone patterns of replacement ewe lambs is available. Therefore, in the present study 40 Assaf female newborn lambs were penned individually and assigned randomly to 1 of 2 treatment groups (n = 20 per treatment). The first group of lambs was fed MR ad libitum (ADLB), whereas the second one (restricted, RES) only received approximately 62.5% of the MR intake measured in the ADLB group. All the lambs were weighed twice a week until they were 35 d old. Then 8 lambs from each group were killed and a morphological study of the gut was performed. Moreover, a piece of liver was cut to measure fat content and oxidative status. The rest of the ewe lambs (24) were weaned and offered a total mixed ration ad libitum to calculate the RFI during the replacement phase. Plasma samples were collected when ewe lambs were 8 mo old to perform a nontargeted metabolomic analysis on a hybrid quadrupole-time-of-flight mass spectrometer coupled to an ultra-high-performance liquid chromatographic system. Progesterone was also measured weekly on serum samples by sequential competitive immunoassay until the end of the experiment (9.5 mo old). The results observed indicate that moderated MR restriction promoted differences in the morphology of the gut of the 35-d-old lambs, but not in the apparent digestibility or feed efficiency traits (RFI) during the replacement phase. However, there was a trend toward reduced live body weight of the RES ewe lambs when they were 9.5 mo old. Moreover, progesterone patterns revealed that only 1 RES versus 4 ADLB ewe lambs had ovulated for the first time at the end of the experiment. This evidence suggests the existence of long-term effects caused by early feed restriction with negative consequences on live body weight and reproductive traits of replacement ewe lambs.

    更新日期:2018-06-30
  • Effects of supplementing rumen-protected niacin on fiber composition and metabolism of skeletal muscle in dairy cows during early lactation
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    J.O. Zeitz, A. Weber, E. Most, W. Windisch, C. Bolduan, J. Geyer, F.-J. Romberg, C. Koch, K. Eder

    Nicotinic acid (NA) has been shown to induce muscle fiber switching toward oxidative type I fibers and a muscle metabolic phenotype that favors fatty acid (FA) utilization in growing rats, pigs, and lambs. The hypothesis of the present study was that supplementation of NA in cows during the periparturient phase also induces muscle fiber switching from type II to type I fibers in skeletal muscle and increases the capacity of the muscle to use free FA, which may help to reduce nonesterified fatty acid (NEFA) flow to the liver, liver triglyceride (TG) accumulation, and ketogenesis. Thirty multiparous Holstein dairy cows were allocated to 2 groups and fed a total mixed ration without (control group) or with ∼55 g of rumen-protected NA per cow per day (NA group) from 21 d before expected calving until 3 wk postpartum (p.p.). Blood samples were collected on d −21, −14, −7, 7, 14, 21, 35, and 63 relative to parturition for analysis of TG, NEFA, and β-hydroxybutyrate. Muscle and liver biopsies were collected on d 7 and 21 for gene expression analysis and to determine muscle fiber composition in the musculus semitendinosus, semimembranosus, and longissimus lumborum by immunohistochemistry, and liver TG concentrations. Supplementation of NA did not affect the proportions of type I (oxidative) or the type II:type I ratio in the 3 muscles considered. A slight shift from glycolytic IIx fibers toward oxidative-glycolytic fast-twitch IIa fibers was found in the semitendinosus, and a tendency in the longissimus lumborum, but not in the semimembranosus. The transcript levels of the genes encoding the muscle fiber type isoforms and involved in FA uptake and oxidation, carnitine transport, tricarboxylic acid cycle, oxidative phosphorylation, and glucose utilization were largely unaffected by NA supplementation in all 3 muscles. Supplementation of NA had no effect on plasma TG and NEFA concentrations, liver TG concentrations, and hepatic expression of genes involved in hepatic FA utilization and lipogenesis. However, it reduced plasma β-hydroxybutyrate concentrations in wk 2 and 3 p.p. by 18 and 26% and reduced hepatic gene expression of fibroblast growth factor 21, a stress hormone involved in the regulation of ketogenesis, by 74 and 56%. In conclusion, a high dosage of rumen-protected NA reduced plasma β-hydroxybutyrate concentrations in cows during early lactation, but failed to cause an alteration in muscle fiber composition and muscle metabolic phenotype.

    更新日期:2018-06-30
  • Dietary supplement of conjugated linoleic acids or polyunsaturated fatty acids suppressed the mobilization of body fat reserves in dairy cows at early lactation through different pathways
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Nanbing Qin, Ali-Reza Bayat, Erminio Trevisi, Andrea Minuti, Piia Kairenius, Sirja Viitala, Mervi Mutikainen, Heidi Leskinen, Kari Elo, Tuomo Kokkonen, Johanna Vilkki

    To investigate the metabolic changes in the adipose tissue (AT) of dairy cows under milk fat depression (MFD), 30 cows were randomly allocated to a control diet, a conjugated linoleic acid (CLA)-supplemented diet, or a high-starch diet supplemented with a mixture of sunflower and fish oil (2:1; as HSO diet) from 1 to 112 d in milk. Performance of animals, milk yield, milk composition, energy balance, and blood metabolites were measured during lactation. Quantitative PCR analyses were conducted on the AT samples collected at wk 3 and 15 of lactation. The CLA and HSO diets considerably depressed milk fat yield and milk fat content at both wk 3 and 15 in the absence of significant changes in milk protein and lactose contents. In addition, the HSO diet lowered milk yield at wk 15 and decreased dry matter intake of cows from wk 3 to 15. Compared with the control, both CLA and HSO groups showed reduced body weight loss, improved energy balance, and decreased plasma concentrations of nonesterified fatty acids and β-hydroxybutyrate at early lactation. The gene expression analyses reflected suppressed lipolysis in AT of the CLA and HSO groups compared with the control at wk 3, as suggested by the downregulation of hormone-sensitive lipase and fatty acid binding protein 4 and the upregulation of perilipin 2. In addition, the HSO diet promoted lipogenesis in AT at wk 15 through the upregulation of 1-acylglycerol-3-phosphate O-acyltransferase 2, mitochondrial glycerol-3-phosphate acyltransferase, perilipin 2, and peroxisome proliferator-activated receptor γ. The CLA diet likely regulated insulin sensitivity in AT as it upregulated the transcription of various genes involved in insulin signaling, inflammatory responses, and ceramide metabolism, including protein kinase B2, nuclear factor κ B1, toll-like receptor 4, caveolin 1, serine palmitoyltransferase long chain base subunit 1, and N-acylsphingosine amidohydrolase 1. In contrast, the HSO diet resulted in little or no change in the pathways relevant to insulin sensitivity. In conclusion, the CLA and HSO diets induced a shift in energy partitioning toward AT instead of mammary gland during lactation through the regulation of different pathways.

    更新日期:2018-06-30
  • Pseudomonas fluorescens group bacterial strains are responsible for repeat and sporadic postpasteurization contamination and reduced fluid milk shelf life
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    S.J. Reichler, A. Trmčić, N.H. Martin, K.J. Boor, M. Wiedmann

    Postpasteurization contamination (PPC) of high temperature, short time-pasteurized fluid milk by gram-negative (GN) bacteria continues to be an issue for processors. To improve PPC control, a better understanding of PPC patterns in dairy processing facilities over time and across equipment is needed. We thus collected samples from 10 fluid milk processing facilities to (1) detect and characterize PPC patterns over time, (2) determine the efficacy of different media to detect PPC, and (3) characterize sensory defects associated with PPC. Specifically, we collected 280 samples of high temperature, short time-pasteurized milk representing different products (2%, skim, and chocolate) and different fillers over 4 samplings performed over 11 mo at each of the 10 facilities. Standard plate count (SPC) as well as total GN, coliform, and Enterobacteriaceae (EB) counts were performed upon receipt and after 7, 10, 14, 17, and 21 d of storage at 6°C. We used 16S rDNA sequencing to characterize representative bacterial isolates from (1) test days with SPC >20,000 cfu/mL and (2) all samples with presumptive GN, coliforms, or EB. Day-21 samples were also evaluated by a trained defect judging panel. By d 21, 226 samples had SPC >20,000 cfu/mL on at least 1 d of shelf life; GN bacteria were found in 132 of these 226 samples, indicating PPC. Crystal violet tetrazolium agar detected PPC with the greatest sensitivity. Spoilage due to PPC was predominantly associated with Pseudomonas (isolated from 101 of the 132 samples with PPC); coliforms and EB were found in 27 and 37 samples with spoilage due to PPC, respectively. Detection of Pseudomonas and Acinetobacter was associated with lower flavor scores; coagulated, fruity fermented, and unclean defects were more prevalent in d-21 samples with PPC. Repeat isolation of Pseudomonas fluorescens group strains with identical partial 16S rDNA sequence types was observed in 8 facilities. In several facilities, specific lines, products, or processing days were linked to repeat product contamination with Pseudomonas with identical sequence types. Our data show that PPC due to Pseudomonas remains a major challenge for fluid milk processors; the inability of coliform and EB tests to detect Pseudomonas may contribute to this. Our data also provide important initial insights into PPC patterns (e.g., line-specific contamination), supporting the importance of molecular subtyping methods for identification of PPC sources.

    更新日期:2018-06-30
  • Effect of αS1-casein genotype on phenolic compounds and antioxidant activity in goat milk yogurt fortified with Rhus coriara leaf powder
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Annamaria Perna, Amalia Simonetti, Giulia Grassi, Emilio Gambacorta

    The aim of this work was to evaluate the phenolic compounds and antioxidant activity of goat milk yogurt characterized by different αS1-casein genotypes and fortified with Rhus coriaria leaf powder. The αS1-casein genotype was determined by isoelectric focusing, total phenol content was determined by the Folin–Ciocalteu method, phenolic compounds were identified and quantified by HPLC-UV analysis, and antioxidant activity was measured using 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid and ferric-reducing antioxidant power. The statistical analysis showed a significant effect of the studied factors. Comparing different genotypes it emerged that yogurt from goats with weak alleles at CSN1S1 loci (FF) showed the lowest phenolic compounds and therefore a lower antioxidant activity compared with yogurt from goats with strong alleles at CSN1S1 loci (AA, BB, AB). Rhus coriaria-fortified yogurt showed a significant increase in total phenolic compounds and antioxidant activity in comparison with plain yogurt. The FF-fortified yogurt presented the lowest total phenol content and antioxidant activity. This could be due to a greater capacity of proteins and peptides in this yogurt to form stable complexes with phenols. The different total phenol content detected in R. coriaria-fortified yogurt indicates that the αS1-casein genotype influenced the amount of added phenols that are bound to the caseins and, therefore, the part that remains free and that affects the biological capacity of the final product.

    更新日期:2018-06-30
  • Graduate Student Literature Review: Detecting health disorders using data from automatic milking systems and associated technologies
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    M.T.M. King, T.J. DeVries

    This review synthesizes a range of research findings regarding behavioral and production responses to health disorders and subsequent illness detection for herds using automatic (robotic) milking systems (AMS). We discuss the effects of health disorders on cow behavior and production, specifically those variables that are routinely recorded by AMS and associated technologies. This information is used to inform the resultant use of behavior and production variables and to summarize and critique current illness detection studies. For conventional and AMS herds separately, we examined research from the past 20 yr and those variables recorded automatically on-farm that may respond to development of illness and lameness. The main variables identified were milk yield, rumination time, activity, and body weight, in addition to frequency of successful, refused, and fetched (involuntary) milkings in AMS herds. Whether making comparisons within cow or between sick and healthy cows, consistent reductions in activity, rumination time, and milk yield are observed. Lameness, however, had obvious negative effects on milk yield but not necessarily on rumination time or activity. Finally, we discuss detection models for identifying lameness and other health disorders using routinely collected data in AMS, specifically focusing on their scientific validation and any study limitations that create a need for further research. Of the current studies that have worked toward disease detection, many data have been excluded or separated for isolated models (i.e., fresh cows, certain lactation groups, and cows with multiple illnesses or moderate cases). Thus, future studies should (1) incorporate the entire lactating herd while accounting for stage of lactation and parity of each animal; (2) evaluate the deviations that cows exhibit from their own baseline trajectories and relative to healthy contemporaries; (3) combine the use of several variables into health alerts; and (4) differentiate the probable type of health disorder. Most importantly, no model or software currently exists to integrate data and directly support decision-making, which requires further research to bridge the gap between technology and herd health management.

    更新日期:2018-06-30
  • Glucocorticoid effects on sheep peripheral blood mononuclear cell proliferation and cytokine production under in vitro hyperthermia
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    M. Caroprese, M.G. Ciliberti, P. De Palo, A. Santillo, A. Sevi, M. Albenzio

    The present experiment aimed at understanding the effects of cortisol levels on sheep peripheral blood mononuclear cell (PBMC) proliferation and cytokine production during hyperthermia. To mimic stress related to the exposition of high ambient temperatures, PBMC were cultured at 43°C for 12 h, and subsequently at 39°C for additional 12 h. Cells in normothermia were cultured at 39°C for 24 h. Phytohemagglutinin-stimulated PBMC were cultured with different cortisol levels: 0 ng/mL; 100 ng/mL, representing the physiological cortisol concentration simulating stress condition (Cort100); and 1,000 ng/mL, representing the hyperactivated hypothalamic-pituitary-adrenal axis (Cort1000). Phytohemagglutinin-stimulated PBMC with 0 ng/mL of cortisol concentration represented the positive control, whereas nonstimulated PBMC without cortisol represented the negative control (NC). The free cell supernatants were collected for the determination of IL-6, IL-1β, and IL-10 by ELISA. Bromodeoxyuridine assay was performed on cells to determine cell proliferation. Exposition to hyperthermia negatively affected cell proliferation, IL-6, IL-1β, and IL-10 concentrations in cell supernatants. The interaction of hyperthermia and cortisol level affected both cell proliferation and IL-10 production. Both PBMC proliferation and IL-10 production in positive control, Cort100, and Cort100 decreased at 43°C as compared with 39°C NC. On average, the Cort100 treatment displayed higher concentrations of IL-6 than NC. The present experiment demonstrated that the action of cortisol concentration simulating stress condition on cell proliferation and cytokine production was a permissive/stimulatory action during normothermia, whereas it was a suppressive action during hyperthermia. These data confirmed that cortisol concentration simulating stress condition could have a role in the immune system of sheep via mediating cellular homeostasis in the condition of hyperthermia. The negative effects of hyperthermia on sheep immune responses were apparent when performing an immunological challenge.

    更新日期:2018-06-30
  • Short communication: Relationships among plasma and milk vitamin B12, plasma free fatty acids, and blood β-hydroxybutyrate concentrations in early lactation dairy cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    M. Duplessis, R.I. Cue, D.E. Santschi, D.M. Lefebvre, C.L. Girard

    This study was undertaken to evaluate the relationship between plasma and milk concentrations of vitamin B12 as well as the relationship between plasma or milk concentrations of vitamin B12 and plasma concentration of free fatty acids (FFA) or blood concentration of β-hydroxybutyrate (BHB) of early lactating Ayrshire (AY) and Holstein (HO) cows. A total of 44 dairy herds (7 AY and 37 HO herds) and 62 AY (21 in first, 19 in second, and 22 in third and more lactations) and 228 HO (51 in first, 74 in second, and 103 in third and more lactation) cows between 3 and 40 d in milk were involved in the study. Hand-stripped milk samples and blood samples were taken 6 h after the morning milking. Milk and plasma samples were analyzed for vitamin B12 concentration and plasma samples were analyzed for FFA concentration. A handheld device was used for blood BHB concentration determination. Thresholds for elevated plasma FFA concentration and hyperketonemia were set at ≥0.70 and ≥1.2 mmol/L, respectively. Vitamin B12 concentration in milk of AY primiparous cows [2,557 (1,995–3,276) pg/mL] was lower than in milk from HO primiparous cows [3,876 (3,356–4,478) pg/mL], whereas no difference was observed among other parities and breeds. Regardless of breeds, plasma concentration of vitamin B12 of first and second parities was lower than plasma concentration of third and more lactation cows. Milk vitamin B12 concentration was positively correlated with plasma vitamin B12 concentration, but the relationship was stronger for AY (ρ averaging 0.63) than for HO cows (ρ averaging 0.36). For AY and HO breeds, a significant relationship between milk or plasma vitamin B12 concentrations and plasma FFA concentration (ρ between 0.29 and 0.59) was observed. Moreover, cows with elevated plasma FFA concentration had greater milk and plasma vitamin B12 concentrations than cows with normal plasma FFA concentration. No relationship between vitamin B12 concentration in milk or plasma and blood BHB concentration and hyperketonemia was noted. In summary, milk is not well correlated with plasma vitamin B12 concentration for HO. It could be hypothesized that elevated plasma concentration of FFA could have a negative effect on the use of vitamin B12 by cow cells, which increases the concentration of the vitamin in plasma and its secretion in milk.

    更新日期:2018-06-30
  • Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-28
    Stephanie R.B. Brown, Emily C. Forauer, Dennis J. D'Amico

    Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ∼4 log10 cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm-high barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N2 and CO2 [100% N2 (MAP1), 30% CO2:70% N2 (MAP2), 50% CO2:50% N2 (MAP3), or 70% CO2:30% N2 (MAP4), 100% CO2 (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO2 had lower pH levels during storage compared with those stored in conditions with lower levels or no CO2 at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO2 content, whereas conditions consisting of 100% N2, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ∼2 log10 cfu/g on cheeses packaged in air, vacuum, and 100% N2 (MAP1) conditions at d 7 and an additional ∼1.5 log10 cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO2 (MAP4) and 100% CO2 (MAP5) limited increases in mean L. monocytogenes counts to <1 log10 cfu/g through 14 d and ∼1.5 log10 cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 on d 21, on d 28 for MAP3 and MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO2 may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.

    更新日期:2018-06-30
  • Effects of different feed type exposure in early life on performance, rumen fermentation, and feed preference of dairy calves
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    J.X. Xiao, L.Y. Guo, G.M. Alugongo, Y.J. Wang, Z.J. Cao, S.L. Li

    The aim of the study was to evaluate the effects of early feed exposure (EFE) to different feedstuffs in dairy calves on feed preference once fed a free-choice diet and a total mixed ration later in life. Thirty (30) female Holstein calves were randomly assigned at birth to 1 of 3 EFE treatments—concentrate only (CON), hay only (HO), and concentrate and hay (COH)—from d 2 to 56. After that, all calves were offered both concentrate and hay in different buckets from d 57 to 70 to allow them free choice between the 2 feedstuffs. Calves were then transferred to a heifer barn, housed within treatment in pairs (2 calves/pen), and fed TMR from d 71 to 196. Feed intake was recorded daily from d 2 to 70 to determine the feed preference before and after weaning. Fresh TMR and orts were collected daily in the last week of the experiment (d 190 to 196) for analysis of feed sorting and intake. Body weight and structural growth were recorded at d 1, 28, 56, 70, and 190. Blood for determining glucose and rumen fluid for determining ruminal pH and volatile fatty acids concentrations were sampled on d 28, 56, 70, and 190. Early feed exposure did not affect feed intake, body weight, average daily gain, blood glucose, and structural growth before and after weaning but did affect feed preference and rumen fermentation. After transition to a free-choice diet, HO calves consumed more hay (550.2 g/d) than CON (177.4 g/d) and COH (396.4 g/d) calves on the first day only. However, COH calves consumed a greater amount of hay, resulting in a higher ratio of hay to total solids compared with either CON or HO calves during d 57 to 70. Upon transition to a TMR, a similar sorting pattern was exhibited between treatments, with calves sorting against the long and for the fine particle fractions. Although no significant long-term effects of different EFE on rumen pH, volatile fatty acids, and blood glucose persisted at wk 27 (from d 190 to 196), calves exposed to COH early had an improved ability to sort for long feed particles compared with CON and HO calves later in life. Our results suggest that EFE could influence choice of feed immediately after weaning and may have long-lasting effects on feed preference in heifers later in life. Further studies with more calves are recommended.

    更新日期:2018-06-22
  • Effect of processing methods and protein content of the concentrate on the properties of milk protein concentrate with 80% protein
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    L.S. Rupp, M.S. Molitor, J.A. Lucey

    In recent years, a large increase in the production of milk protein concentrates (MPC) has occurred. However, compared with other types of milk powders, few studies exist on the effect of key processing parameters on powder properties. In particular, it is important to understand if key processing parameters contribute to the poor solubility observed during storage of high-protein MPC powders. Ultrafiltration (UF) and diafiltration (DF) are processing steps needed to reduce the lactose content of concentrates in the preparation of MPC with a protein content of 80% (MPC80). Evaporation is sometimes used to increase the TS content of concentrates before spray drying, and some indications exist that inclusion of this processing step may affect protein properties. In this study, MPC80 powders were manufactured by 2 types of concentration methods: membrane filtration with and without the inclusion of an evaporation step. Different concentration methods could affect the mineral content of MPC powders, as soluble salts can permeate the UF membrane, whereas no mineral loss occurs during evaporation, although a shift in calcium equilibrium toward insoluble forms may occur at high protein concentration levels. It is more desirable from an energy efficiency perspective to use higher total solids in concentrates before drying, but concerns exist about whether a higher protein content would negatively affect powder functionality. Thus, MPC80 powders were also manufactured from concentrates that had 3 different final protein concentrations (19, 21, and 23%; made from 1 UF retentate using batch recirculation evaporation, a similar concentration method). After manufacture, powders were stored for 6 mo at 30°C to help understand changes in MPC80 properties that might occur during shelf-life. Solubility and foaming properties were determined at various time points during high-temperature powder storage. Inclusion of an evaporation step, as a concentration method, resulted in MPC80 that had higher ash, total calcium, and bound calcium (of rehydrated powder) contents compared to concentration with only membrane filtration. Concentration method did not significantly affect the bulk (tapped) density, solubility, or foaming properties of the MPC powders. Powder produced from concentrate with 23% protein content exhibited a higher bulk density and powder particle size than powder produced from concentrate that had 19% protein. The solubility of MPC80 powder was not influenced by the protein content of the concentrate. The solubility of all powders significantly decreased during storage at 30°C. Higher protein concentrations in concentrates resulted in rehydrated powders that had higher viscosities (even when tested at a constant protein concentration). The protein content of the concentrate did not significantly affect foaming properties. Significant changes in the mineral content are used commercially to improve MPC80 solubility. However, although the concentration method did produce a small change in the total calcium content of experimental MPC80 samples, this modification was not sufficiently large enough (<7%) to influence powder solubility.

    更新日期:2018-06-22
  • A mathematical model of in vivo bovine blastocyst developmental to gestational Day 15
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    P.R. Shorten, M. Donnison, R.M. McDonald, S. Meier, A.M. Ledgard, D. Berg

    Bovine embryo growth involves a complex interaction between the developing embryo and the growth-promoting potential of the uterine environment. We have previously established links between embryonic factors (embryo stage, embryo gene expression), maternal factors (progesterone, body condition score), and embryonic growth to 8 d after bulk transfer of Day 7 in vitro-produced blastocysts. In this study we recovered blastocysts on Days 7 and 15 after artificial insemination to test the hypothesis that in vivo and in vitro embryos follow a similar growth program. We conducted our study using 4 commercial farms and repeated our study over 2 yr (2014, 2015), with data available from 2 of the 4 farms in the second year. Morphological and gene expression measurements (196 candidate genes) of the Day 7 embryos were measured and the progesterone concentration of the cows were measured throughout the reproductive cycle as a reflection of the state of the uterine environment. These data were also used to assess the interaction between the uterine environment and the developing embryo and to examine how well Day 7 embryo stage can be predicted from the Day 7 gene expression profile. Progesterone was not a strong predictor of in vivo embryo growth to Day 15. This contrasts with a range of Day 7 embryo transfer studies which demonstrated that progesterone is a very good predictor of embryo growth to Day 15. Our analysis demonstrates that in vivo embryos are 3 times less sensitive to progesterone than in vitro-transferred embryos (up to Day 15). This highlights that caution must be applied when extrapolating the results of in vitro embryo transfer studies to the in vivo situation. The similar variance in measured and predicted (based on Day 15 length) Day 7 embryo stage indicate low stochastic perturbations for in vivo embryo growth (large stochastic growth effects would generate a significantly larger standard deviation in measured embryo length on Day 15). We also identified that Day 7 embryo stage could be predicted based on the Day 7 gene expression profile (58% overall success rate for classification of 5 embryo stages). Our analysis also associated genes with each developmental stage and demonstrates the high level of temporal regulation of genes that occurs during early embryonic development.

    更新日期:2018-06-22
  • How electrodialysis configuration influences acid whey deacidification and membrane scaling
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    Guillaume Dufton, Sergey Mikhaylin, Sami Gaaloul, Laurent Bazinet

    With the rising popularity of Greek-style yogurts in the past few years, the production of acid whey has drastically increased. If sweet whey is usually further processed, the acid whey valorization comes with challenges because its drying is jeopardized by its high mineral and organic acid contents. For this reason, prior demineralization and deacidification are usually performed at industrial scale using a combination of ion exchange resins and electrodialysis. This whole process represents large amounts of resources and energy consumption as well as an important production of effluents. The optimization of the electrodialysis technique, currently the focus of a few studies, could result in the replacement of the serial processes and would provide a cost-effective and eco-efficient alternative. In this work, the demineralization and deacidification of acid whey were compared via 2 electrodialysis configurations: one conventional and one using bipolar membranes. Both configurations allowed to reach interesting demineralization (67%) and deacidification (44%) rates. However, even though the appearance of fouling or scaling has never been reported, scalings of different natures were observed on membranes using both configurations. Amorphous calcium phosphate was identified on the anion exchange membranes for both configurations while calcite and brucite were identified on cation exchange ones using the bipolar membrane configuration. These scaling formations were linked to the migration of divalent ions and water splitting phenomenon caused by a high demineralization rate or by an already formed significant scaling.

    更新日期:2018-06-22
  • Short communication: Extended-spectrum AmpC–producing Escherichia coli from milk and feces in dairy farms in Brazil
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    G.S. Santiago, I.S. Coelho, G.F. Bronzato, A.B. Moreira, D. Gonçalves, T.A. Alencar, H.N. Ferreira, B.G. Castro, M.M.S. Souza, S.M.O. Coelho

    The AmpC enzyme normally is expressed constitutively in Escherichia coli, and its overproduction confers resistance to cefoxitin. A newly reported AmpC, the extended-spectrum AmpC (ESAC), is related to resistance to cefepime, a fourth-generation cephalosporin. This enzyme presents more flexibility in the active site due to insertions, replacements, and deletions on AA sequences. Many isolates producing ESAC were reported in human clinical isolates, but E. coli ESAC producers were reported in animals only in France. The animal E. coli strains can produce this enzyme and possibly disseminate it to human and production environments. In our study, 3 strains of E. coli from milk and feces bovine samples, collected in Rio de Janeiro, Brazil, were suspected to produce ESAC. After excluding other mechanisms of resistance, the gene was sequenced to verify ESAC characteristics. These strains presented replacement of AA in omega and R2 loops, suggesting ESAC production. This is the first report to study ESAC E. coli in dairy farms in Brazil.

    更新日期:2018-06-22
  • Injectable trace minerals (selenium, copper, zinc, and manganese) alleviates inflammation and oxidative stress during an aflatoxin challenge in lactating multiparous Holstein cows
    J. Dairy Sci. (IF 2.749) Pub Date : 2018-06-21
    R.T. Pate, F.C. Cardoso

    Trace minerals are vital in the antioxidant response during oxidative stress; however, limited research is available on the effects of trace mineral supplementation during an aflatoxin (AF) challenge. The objective of the study was to determine the effects of 2 subcutaneous injections of 15 mg/mL of Cu, 5 mg/mL of Se, 60 mg/mL of Zn, and 10 mg/mL of Mn (Multimin 90, Multimin North America, Fort Collins, CO) given at 1 mL/90.7 kg of average body weight in response to an AF challenge. Fifty-eight Holstein cows [body weight (mean ± SD) = 734 ± 6 0kg; days in milk = 191 ± 93] were assigned to 1 of 3 treatments in a randomized complete block design. The experimental period (63 d) was divided into an adaptation phase (d 1–56) and a measurement phase (d 57–63). From d 57 to 59, cows received an AF challenge that consisted of 100 μg of aflatoxin B1/kg of dietary dry matter intake (DMI) administered orally via balling gun. Treatments were saline injection and no AF challenge (NEG), saline injection and AF challenge (POS), and trace mineral injection and AF challenge (MM). Injections were performed subcutaneously on d 1 and 29. Milk was sampled 3 times daily from d 56 to 63, blood was sampled on d 0, 56, 60, and 63, and liver samples were taken on d 0 and 60. Two treatment orthogonal contrasts [CONT1 (NEG vs. POS) and CONT2 (POS vs. MM)] were made. Cows in NEG had lower AF excretion in milk and greater 3.5% fat-corrected milk (32.1 ± 1.37 kg/d) compared with cows in POS (28.6 ± 1.43 kg/d). Feed efficiencies (3.5% fat-corrected milk/DMI, energy-corrected milk/DMI, and milk/DMI) were greater for cows in NEG (1.42 ± 0.07, 1.46 ± 0.07, and 1.45 ± 0.07, respectively) than cows in POS (1.16 ± 0.08, 1.18 ± 0.08, and 1.22 ± 0.07, respectively). Cows in POS had greater milk urea nitrogen and blood urea nitrogen than cows in MM. Liver concentrations of Se and Fe were greater for cows in MM compared with cows in POS. Cows in MM tended to have greater plasma glutathione peroxidase activity compared with cows in POS. An upregulation of liver GPX1 was observed for cows in POS compared with cows in MM. In conclusion, subcutaneous injection of trace minerals maintained an adequate antioxidant response when an AF challenge was present.

    更新日期:2018-06-22
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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