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  • Nitrogen concentration in the upper leaves of the canopy is a reliable indicator of plant N nutrition in both pure and mixed grassland swards
    Grass Forage Sci. (IF 1.814) Pub Date : 2020-01-17
    Gaëtan Louarn; Abad Chabbi; François Gastal

    Effective indicators of plant nitrogen (N) nutrition are needed to improve N management in grasslands. This is particularly the case for mixtures that rely on N fixation by legumes as a major N input, because no reference tool such as the nitrogen nutrition index (NNI) exists under these conditions. The aims of this study were to test the reliability of a plant‐based index, the N concentration of upper leaves in the canopy (Nup), as a possible alternative for NNI in both pure and mixed grasslands. Data were gathered from four experiments covering a range of pure and mixed grasslands under different N fertilization levels. A cross‐validation of Nup predictions against NNI in pure stands, and against two NNI‐derived indices in mixtures, was performed. The Nup values appeared to be linearly related to NNI in pure stands of both grasses and legumes. The relationship was identical for the two groups of species and explained up to 86% of NNI variability. In mixtures, Nup also displayed a linear relationship with the two other tested indices, explaining 65% and 78% of variability. The conclusions of the three indices diverged with respect to strongly unbalanced mixtures, where the assumptions regarding the computation of NNI‐derived indices were not met. Excluding these situations, the overall relationship between Nup and NNI proved to be identical for mixtures and pure stands. The results suggest that Nup is a valid criterion for plant N nutrition which applies to a broad range of grassland species and to mixture conditions.

  • Identifying causes of low persistence of perennial ryegrass (Lolium perenne) dairy pasture using the Basic Grassland model (BASGRA)
    Grass Forage Sci. (IF 1.814) Pub Date : 2020-01-16
    Simon J. R. Woodward; Marcel Van Oijen; Wendy M. Griffiths; Pierre C. Beukes; David F. Chapman

    Recent years have seen a decline in herbage production and tiller populations in New Zealand's perennial ryegrass (Lolium perenne) dairy pastures. One hypothesis is that modern genotypes are less suited to the warmer, drier weather experienced under changing climate patterns. In this study, a combination of long‐term trial data (2011–2017) and a process‐based pasture model (BASGRA) was used to explore the causes and possible mitigation of the observed production and population loss at three sites (dryland sites in Northland and Waikato and an irrigated site in Canterbury). Bayesian calibration was used to identify the model parameter sets that were consistent with the trial data and to identify differences in plant morphology and responses between sites. The model successfully simulated the observed differences in tiller numbers between the dryland sites, where populations and production declined rapidly after the second year and the irrigated site where populations and production were maintained. Analysis of the model calibrations along with preliminary scenario simulations suggests that increased tiller mortality associated with drought was the main cause of persistence failure at the dryland sites and that decreasing grazing pressure or breeding for tolerance to higher temperatures may not be successful in preventing this.

  • Long‐term evolution and prediction of feed value for permanent mountain grassland hay: Analysis of a 32‐year data set in relation to climate change
    Grass Forage Sci. (IF 1.814) Pub Date : 2020-01-13
    Bertrand Deroche; Philippe Pradel; René Baumont

    Elevation of mean air temperature related to climate change speeds up plant maturity, which influences mostly forage feed value. The objective of the study was to assess variation in hay quality harvested over 32 years at the same experimental site, and whether feed value is better predicted by combining agro‐climatic variables with chemical composition. From 1979 to 2010, the in vivo digestibility (OMd) and voluntary dry matter intake (VDMI) of 271 hays, harvested during the first vegetation cycle on permanent grasslands, were measured in sheep. Over 32 years, the mean air temperature between February and August increased significantly by 1.34°C. Cutting date was advanced by 6 days, but the average sum of temperature at cutting (ST) increased significantly by 13%. Crude protein (CP) content declined (−22%, p < .001), crude fibre content increased (+8%, p < .001), OMd decreased (−3%, p = .012) and VDMI increased (+9%, p = .011). Changes in the chemical composition and OMd were consistent with the increase in ST. Finally, the prediction of OMd from CP and crude fibre contents (R2 = .57, RMSE = 2.99) was slightly improved by the addition of ST and hay drying time (R2 = .60, RMSE = 2.83). Climate change may have a negative indirect effect on hay quality if an earlier cutting date does not compensate for its effect on the faster maturation of the plants. Moreover, agro‐climatic criteria could help to monitor and predict hay quality in relation to intra‐ and inter‐annual climatic changes.

  • Management strategies for forage rape (Brassica napus L. cv Goliath): Impact on dry‐matter yield, plant reserves, morphology and nutritive value
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-12-30
    M. R. Islam; Sergio C Garcia; Ajantha Horadagoda; Kendra L. Kerrisk; Cameron E. F. Clark

    Limited information is available on the grazing management principles of forage rape (Brassica napus L.), particularly in relation to grazing height and intensity and the impact of these on dry‐matter (DM) yield and nutritive value. A glasshouse study was undertaken to investigate the effect of three defoliation heights (plant height at harvest; DH: 40, 70 and 90 cm; L, M and H DH respectively) and three defoliation intensities (height at which plants were cut; DI: 5, 20 and 35 cm of residual height; H, M and L DI respectively) on forage rape (cv Goliath) yield and nutritive value at two harvests (harvest 1, H1 and harvest 2, H2), and the impact of nitrogen (N) and water soluble carbohydrate (WSC) reserves on regrowth. Increasing DH from L to H increased estimated total DM yield (H1 plus H2) from 0.5 to 4.6 t DM/ha but DI did not affect yield. Dry‐matter yield was optimized at 90 cm DH, but greater nutritive value was achieved by harvesting at lower levels of DH. Despite high in vitro DM digestibility (IVDMD; 852–889 g/kg), harvesting at 90 cm DH could not meet the protein requirement of lactating dairy cows and harvesting at lower levels risks nitrate poisoning. Our results indicate the optimum DH may be between 70 and 90 cm DH, and 20 and 35 cm DI, which requires further studies.

  • Production of beef cattle grazing on Brachiaria brizantha (Marandu grass)—Arachis pintoi (forage peanut cv. Belomonte) mixtures exceeded that on grass monocultures fertilized with 120 kg N/ha
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-12-12
    José Marques Pereira; Claudia de Paula Rezende; Augusto Magno Ferreira Borges; Bruno Grossi Costa Homem; Daniel Rume Casagrande; Thasia Martins Macedo; Bruno José Rodrigues Alves; Selenobaldo Alexinaldo Cabral de Sant’Anna; Segundo Urquiaga; Robert Michael Boddey

    Mixed grass/legume pastures are an alternative to grass monocultures for increased beef cattle production in tropical climates. The objective of this study was to evaluate the productivity of beef cattle grazing either a mixed pasture of Brachiaria brizantha cv. Marandu grass and Arachis pintoi (forage peanut) cv. Belomonte or a Marandu monoculture, under rotational stocking. Five trials were conducted over a period of nine years in north‐eastern Brazil where the sward structure (forage, grass and legume mass) and animal performance were compared for a mixed Marandu grass/forage peanut pasture, and a Marandu grass monoculture with 120 kg N ha−1 y−1. Stocking rate was adjusted to maintain forage allowance at 4% body weight/day. A block design was used with four replicates, and warm and cool seasons within each trial were considered, using repeated measurements over time. In the warm season, the forage mass in the mixed pastures was 17% greater than in the monoculture (p = .049), and the stocking rate, average daily gain and liveweight gain per ha were 16.4%, 20.0% and 28.7% greater (p = .004, p < .001 and p < .001 respectively). The average daily gain showed a positive linear relationship with the legume proportion in the sward (p < .001). The mixed forage peanut/Marandu pasture sustained significantly greater beef cattle production (789 kg ha−1 y−1) compared to the N‐fertilized grass monoculture (655 kg ha−1 y−1). Appropriately managed, mixed pastures of forage peanut/Brachiaria pastures are sustainable and have high potential for use in the humid tropics.

  • A two‐year comparison on nutritive value and yield of eight lucerne cultivars and one red clover cultivar
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-12-09
    Dannylo O. Sousa; Hanne H. Hansen; Ola Hallin; Luiz G. Nussio; Elisabet Nadeau

    Red clover (Trifolium pratense) and lucerne (Medicago sativa) are among the most common legume species used for ruminant feeding systems. Besides the greater nutritive quality and first‐year ley yield compared to lucerne, red clover decreases its yield over the years. However, under unfavourable soil conditions the persistency of lucerne can be compromised, not performing as expected. This study compared yield and chemical composition of eight lucerne cultivars and one tetraploid red clover cultivar, with similar growth capacity as lucerne, replicated over two years. In the second year, four lucerne cultivars and the red clover cultivar were analysed for crude protein (CP) fractions, dry matter and neutral detergent fibre (NDF) digestibility. A randomized block design was used with three field blocks per cultivar for the multiple comparisons within each year. There were differences in DM yield, concentrations of CP and NDF and CP fractions among the lucerne cultivars, but the differences were inconsistent between years and between growth cycles within year. The red clover cultivar had lower CP and NDF concentrations than a majority of the lucerne cultivars, and greater in vitro organic matter digestibility compared to all of the lucerne cultivars. Also, the red clover cultivar had greater rumen undegradable‐to‐degradable CP ratio but confirmed its lower yield persistency compared to the lucerne cultivars.

  • Some challenges and opportunities for grazing dairy cows on temperate pastures
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-12-02
    J. Michael Wilkinson; Michael R. F. Lee; M. Jordana Rivero; A. Thomas Chamberlain

    Grazing plays an important role in milk production in most regions of the world. In this review, some challenges to the grazing cow are discussed together with opportunities for future improvement. We focus on daily feed intake, efficiency of pasture utilization, output of milk per head, environmental impact of grazing and the nutritional quality to humans of milk produced from dairy cows in contrasting production systems. Challenges are discussed in the context of a trend towards increased size of individual herds and include limited and variable levels of daily herbage consumption, lower levels of milk output per cow, excessive excretion of nitrogenous compounds and requirements for minimal periods of grazing regardless of production system. A major challenge is to engage more farmers in making appropriate adjustments to their grazing management. In relation to product quality, the main challenge is to demonstrate enhanced nutritional/processing benefits of milk from grazed cows. Opportunities include more accurate diet formulations, supplementation of grazed pasture to match macro‐ and micronutrient supply with animal requirement and plant breeding. The application of robotics and artificial intelligence to pasture management will assist in matching daily supply to animal requirement. Wider consumer recognition of the perceived enhanced nutritional value of milk from grazed cows, together with greater appreciation of the animal health, welfare and behavioural benefits of grazing should contribute to the future sustainability of demand for milk from dairy cows on pasture.

  • Microbial community dynamics and their contributions to organic acid production during the early stage of the ensiling of Napier grass (Pennisetum purpureum)
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-13
    XianJun Yuan; ZhiHao Dong; JunFeng Li; Tao Shao

    The study aimed to disclose the microbial community dynamics and their contributions to organic acid production during the ensiling of Napier grass. Napier grass was harvested at the vegetative growth phase and ensiled for 30 days. Three silos were opened after 1, 2, 3, 5, 7, 14, and 30 days of ensiling respectively. The intensive fermentation was observed during the initial stage of ensiling, indicated by lower pH (<4.0) on d 2 of ensiling. Lactic acid (LA) was the primary fermentation product, although acetic acid (AA) concentration rapidly increased and LA/AA concentration gradually decreased after 3 days of ensiling. The ethanol concentration was already 11.8 g/kg DM on d 1 of ensiling and then remained stable until the end of ensiling. Lactococcus was the predominant genus during the initial 2 days of ensiling, and then, it was gradually replaced by Lactobacillus. The increase in ammonia nitrogen and butyric acid concentration after 7 days of ensiling was attributed to the growth of Clostridia, which is favored by the high moisture concentration in the Napier grass. The natural ensiling of Napier grass displayed LA‐type fermentation and was dominated by the fermentation of Lactobacillus and Lactococcus. Lactobacillus is mainly responsible for the LA production during the ensiling of Napier grass.

  • On the uniform distribution and optimal consumption of stretch film used for wrapping cylindrical baled silage
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-09-10
    Anna Stankiewicz

    The main objective of this article was to mathematically formulate the problem of the uniform coverage of round baled silage, solve this problem and propose a design approach. A mathematical model which describes the distribution and consumption of stretch film used for bale wrapping is derived. The model aims at capturing more features of a realistic description of the wrapping process than existing mathematical models, so as to provide a deeper insight into the issues concerning bale coverage and film consumption. Bale and film dimensions, mechanical properties of the stretch film described by the Poisson ratio and unit deformation, the overlap between adjacent film strips and the pre‐assumed number of basic film layers are taken into account. It is proved that the complete set of the overlap ratios guaranteeing uniform film distribution is composed of irreducible fractions in which dividend is the divisor minus one. For the bale wrapping technique, only the first four equal to are significant. However, the essence of this study is the uniform film distribution, but optimization and robustness issues are also discussed. Simple mathematical rules are derived to calculate the optimal overlap ratios which minimize film usage. The parallelism between the uniform film distribution and minimal film usage is demonstrated, but it is also proved that these requirements are not equivalent. Robustness on the wrapping process disturbances is examined, and two algorithms for robustly optimal overlap ratio design are developed. The main developments are illustrated by examples, figures and supporting discussions.

  • A meta‐analysis examining lactic acid bacteria inoculants for maize silage: Effects on fermentation, aerobic stability, nutritive value and livestock production
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-10-30
    Alexandre Bernardi; Carla J. Härter; Antonio W. L. Silva; Ricardo A. Reis; Carlos H. S. Rabelo

    A database containing 140 articles published in journals (731 treatment means evaluated) was used to examine the effect of different lactic acid bacteria (LAB) on fermentation, chemical composition and aerobic stability of maize (corn) silage. Compared with the control, dry matter (DM) loss increased by 8% and 50% (p < .01) due to inoculation of maize silage with either homolactic LAB (hoLAB) or heterolactic LAB (heLAB). In vitro DM digestibility of maize silage increased only with hoLAB inoculation (+2.22%; p < .01). The heLAB inoculation increased (p < .01) the aerobic stability of maize silage by 71.3 hr. To investigate the effect of silage inoculation on livestock production, a second database comprising 35 articles [99 treatment means evaluated based on results from 648 cattle (429 beef cattle and 219 dairy cows) and 298 sheep] was used. Inoculation of maize silage with either hoLAB or heLAB did not affect milk yield (p > .05), but their combination (mixLAB) depressed milk yield (–2.5 kg/day; p < .01). Inoculation with hoLAB increased DM intake in sheep (+0.15 kg/day; p = .02), but decreased it in beef cattle (–0.26 kg/day; p = .01) without affecting average daily gain for both sheep and beef cattle (p ≥ .06). In conclusion, fermentative loss increased regardless of the bacterial inoculant used, while aerobic stability increased mainly by using heLAB. Benefits from hoLAB inoculation on animal performance were noted only for feed intake in sheep, while productive performances of dairy cows and beef cattle were not improved.

  • Occurrence of filamentous fungi and mycotoxins in wrapped forages in Sweden and Norway and their relation to chemical composition and management
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-08
    Jessica Schenck; Cecilia Müller; Annika Djurle; Dan Funck Jensen; Martin O’Brien; Astrid Johansen; Peter Have Rasmussen; Rolf Spörndly

    A study was conducted on 124 farms in Sweden and Norway where fungal (all farms) and mycotoxin (100 of the 124 farms) presence was examined in wrapped forage bales. Samples were also analysed for chemical composition, and data on the bale production and storage system on each farm were collected. Fungi, analysed by three common sampling methods, were found in bales from 89% of the visited farms (110 farms). The most frequently isolated fungal species from the bale surface was Penicillium roqueforti. Mycotoxins were present in 39% of the 100 samples analysed. The most common mycotoxins present were enniatin B (14 farms) followed by deoxynivalenol (12 farms). The risk of finding fungi in baled forage samples was higher with odds ratio (OR) of 5.1 when less than eight layers of stretch film were applied, low seal integrity of wrapping (OR 172 at <10 s of seal integrity), higher dry‐matter content (OR 1.17–1.56 per % unit DM) and higher concentrations of acetic acid (OR 47.5 per g DM) and ethanol (OR 3.4 per g DM). Mycotoxin presence was not found to be correlated with any of the chemical characteristics of the baled forage, or with any forage production and management factors. A positive correlation was present between total fungal counts and general mycotoxin presence, but not between specific mycotoxins and the toxin‐producing fungal species.

  • Effects of including bioactive legumes in grass silage on digestion parameters, nitrogen balance and methane emissions in sheep
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-06
    Vincent Niderkorn; Giuseppe Copani; Cécile Martin; Gaëlle Maxin; Angélique Torrent; Frédéric Anglard; Yvanne Rochette; Cécile Ginane

    The aim of this work was to investigate the effects of feeding sheep with silage mixtures containing bioactive legumes on intake and digestive parameters. The bioactive legumes used were sainfoin (SF, Onobrychis viciifolia) and red clover (RC, Trifolium pratense), which contain condensed tannins (CT) and polyphenol oxidase respectively. Five treatments were assigned to two groups of sheep according to a replicated 5 × 5 Latin square design. The five types of silages tested were, on a dry matter (DM) basis: pure timothy grass silage (Phleum pratense, control, T), three binary mixtures of T‐SF, T‐RC and RC‐SF (500 g/kg each) and a ternary mixture of T‐RC‐SF (500, 250 and 250 g/kg respectively). The daily voluntary DM intake of silage mixtures containing both SF and RC was greater than for pure T silage, while the presence of SF resulted in lower organic matter digestibility compared to pure T. The rumen disappearance rate measured in situ increased linearly with the presence of SF and RC in silage. The nitrogen (N) digestibility was greater for pure T and T‐RC than for T‐SF, and the amount of N retained daily by the animals was greater for RC‐containing silages than for T and T‐SF. The methane (CH4) yield was greater for pure T than for the silage mixtures containing SF. We conclude that the presence of RC in silage could boost performances through intake and N retention, while SF‐based mixtures appear to have reduced negative environmental impacts through the reduction of CH4 emissions.

  • Grazing management for more resilient mixed livestock farming systems on native grasslands of southern South America
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-08-25
    Pablo Modernel; Valentin Picasso; Martin Do Carmo; Walter A. H. Rossing; Marc Corbeels; Pablo Soca; Santiago Dogliotti; Pablo Tittonell

    Droughts in southern South America affect grazing systems in many ways. They reduce biomass productivity; decrease livestock feed intake, weight and reproductive performance; increase farmers’ costs; and reduce farm income. It was hypothesized that simple grazing management variables affect the resilience of grazing systems to droughts at the paddock and farm scales. The effects of grazing management on herbage and animal production were assessed at paddock level, and how technological and structural variables relate to the production and economic performances at farm level. Results of a grazing experiment controlling herbage allowance at paddock level showed that resistance of herbage accumulation and animal live weight to drought was significantly higher for paddocks with higher pre‐drought herbage allowance than for those managed to low herbage allowance treatments. A strong positive linear relationship was found between pre‐drought herbage height and resistance of herbage accumulation rate (p < .01). In a longitudinal study of nine farms in Uruguay, resistance of cow pregnancy rate to drought was positively correlated with cow pregnancy rate (r = .72, p = .02) and farm net income (r = .78, p = .02), and negatively correlated with sheep‐to‐cattle ratio (r = −.80, p = .01). These correlations suggest that farms with higher incomes and low proportions of sheep in the herd withstand drought better (in terms of pregnancy rate). Four common regional production strategies were identified that react differently when farmers face drought, and these results can aid farmers in those regions to design more resilient mixed livestock farming systems and can inform policymakers about effective strategies for mitigating drought impacts in the region.

  • Forage and animal production on palisadegrass pastures growing in monoculture or as a component of integrated crop–livestock–forestry systems
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-10-21
    Perivaldo de Carvalho; Leandro Ferreira Domiciano; Mircéia Angele Mombach; Hemython Luis Bandeira do Nascimento; Luciano da Silva Cabral; Lynn E. Sollenberger; Dalton Henrique Pereira; Bruno Carneiro Pedreira

    To meet the global demand for animal protein, sustainable intensification of existing livestock systems may be possible, especially through integration of livestock with crops or forestry. Thus, our objective was to compare forage production and animal performance in grass monoculture and integrated systems in the Brazilian Amazon biome. The four systems were (a) livestock (L) with Marandu palisadegrass {Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster} as monoculture, (b) palisadegrass pastures integrated with eucalyptus trees (Eucalyptus urograndis; hybrid of Eucalyptus grandis W. Hill ex Maiden and Eucalyptus urophylla S. T. Blake) arranged in three‐row groves with groves spaced 30 m apart (livestock–forestry; LF), (c) palisadegrass after two years of crops (crop–livestock; CL) and (d) palisadegrass after two years of crops with single rows of eucalyptus trees spaced 37 m apart (crop–livestock–forestry; CLF). From July 2016 to July 2017, all experimental units were continuously stocked using a variable stocking rate. Greater herbage accumulation (HA) occurred in CL and CLF in comparison with L and LF (21,310, 24,050, 19,500 and 18,890 kg DM/ha respectively). The gain per hectare of L, LF and CL (average of 932 kg ha–1) was less than CLF (1,190 kg ha–1). Average daily gain was similar among systems (0.69 kg/day). We conclude that integrated systems can support similar (LF or CL) or greater (CLF) levels of animal production than palisadegrass monocultures while increasing diversity of outputs, thereby providing a greater range of viable systems for livestock production in the Brazilian Amazon biome.

  • Post‐grazing cutting management in tall fescue affects the sward structure, forage and liveweight production
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-09-11
    Jorge Omar Scheneiter; Jonatan Nicolás Camarasa; Daniel Aperlo; Martín Alejandro Ferrari; Martín Nalino; María J. Beribe

    Tall fescue is the main perennial grass of the pastures of the temperate region of Argentina. However, after flowering in spring, tall fescue loses productivity and quality. Based on this, the objective of this work was to evaluate the effects of different post‐grazing mechanical cutting managements on the forage mass, leaf proportion, stocking rate, liveweight gain and liveweight production of tall fescue pastures. The treatments were post‐grazing mechanical cutting at anthesis (FC), post‐grazing mechanical cutting throughout spring and summer (SSC), and no post‐grazing mechanical cutting (NC). The experiment was performed from 2011 to 2014 in Argentina. The greatest and lowest forage mass were determined in September–November and May–September respectively. The leaf proportion of the SSC treatment was greater than that of the NC treatment, except in September–November. NC had higher stocking rate and lower liveweight gain than SSC, and neither NC nor SSC differed from FC. The liveweight production of the treatments was characterized by a trade‐off between stocking rate and liveweight gain. We conclude that FC is an attractive management because, with a single post‐grazing cutting, swards remain productive and leafy.

  • CO2 fertilization does not affect biomass production and nutritive value of a C4 tropical grass in short timeframe
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-08-12
    Adibe Luiz Abdalla Filho; Paulo de Mello Tavares Lima; Gabriel Zanuto Sakita; Tairon Pannunzio Dias e Silva; Wilian dos Santos da Costa; Raquel Ghini; Adibe Luiz Abdalla; Marisa de Cássia Piccolo

    Increased atmospheric carbon dioxide (CO2) is a consequence of recent anthropogenic environmental changes, and few studies have evaluated its effects on tropical grasses used in Brazilian pastures, the main feed source for major part of ruminant livestock. This study evaluated forage production, chemical composition, in vitro total gas production and organic matter degradability of Brachiaria brizantha under contrasting CO2 atmospheric conditions in a free air carbon dioxide enrichment (FACE) facility. The forage plants were sown in each of the 12 octagonal rings of the FACE facility: six under ambient atmospheric CO2 concentration of approximately 390 μmol/mol, hereafter referred to as control (CON) plots, and other six rings enriched with pure CO2 flux to achieve a target CO2 concentration of 550 μmol/mol, hereafter called elevated CO2 (eCO2) plots. Soil samples were collected to determine carbon and nitrogen concentrations. After seventy days of sowing, a standardization cutting was performed and then at regular intervals of 21 days the forage was harvested (ten harvest dates) and forwarded to laboratorial analyses. Forage above‐ground biomass production (dry matter (DM): 6,143 vs. 6,554 kg/ha), as well as morphological characteristics (leaves: 71% vs. 68%; stem: 28% vs. 31%), chemical composition (crude protein: 162.9 vs. 161.8; neutral detergent fibre: 663.8 vs. 664.3; acid detergent fibre: 369.5 vs. 381; lignin: 60.1 vs. 64.1 g/kg DM; total C: 45.9 vs. 45.9; total N: 2.8 vs. 2.8; total S: 0.2% vs. 0.2%), organic matter in vitro degradability (573.5 vs. 585.3 g/kg), methane (5.7 vs. 4.3 ml/g DM) and total gas (128.3 vs. 94.5 ml/g DM) production did not differ significantly between CON and eCO2 treatments (p > .05). The results indicated that at least under short‐term enrichment, B. brizantha was not affected by eCO2.

  • Combining ability among apomictic and sexual parents of Urochloa humidicola
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-10-22
    Ulisses José de Figueiredo; Sanzio Carvalho Lima Barrios; Cacilda Borges do Valle; José Airton Rodrigues Nunes

    The diallel cross constitutes an informative genetic design for choosing genitors and crosses in breeding programmes since it provides estimates of general (GCA) and specific (SCA) combining abilities. Because the breeding programme for Urochloa humidicola ([Rendle] Morrone & Zuloaga; syn. Brachiaria humidicola [Rendle] Schweick) at Embrapa Beef Cattle is recent, these estimates are still unknown. Thus, the aim of this study was to obtain the estimates of GCA and SCA from the partial diallel cross design between sexual and apomictic parents. The crosses involved nine sexual and ten apomictic parents. Seventy‐one full‐sib progenies were obtained and evaluated in an incomplete block design, using all parents and the cv. BRS Tupi as a check. The agronomic and forage quality traits were evaluated using seven harvests. Statistical analysis was performed using the mixed model approach. Significant variations were associated with GCA among sexual parents for biomass yield and forage quality traits. However, this cannot be observed for apomictic parents for GCA. The SCA effect was not significant for the assessed traits. These results showed the predominance of additive effects. Sexual parents SEX3 and SEX4 presented the highest potential for contributing favourable alleles in hybrid combinations. The absence of GCA among apomictic parents and SCA suggests the need to increase genetic variability for the generation of breeding populations of U. humidicola.

  • Estimation of lucerne yield stability for enabling effective cultivar selection under rainfed conditions
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-15
    Josef Hakl; Seyed Mohammad Ali Mofidian; Zdeňka Kozová; Pavel Fuksa; Šantrůček Jaromír

    Evaluation of crop and forage yield stability is of increasing relevance in the context of current and recent environmental changes but, in contrast to other field crops, there are no published systematic analyses among forage crops in Europe. A study of stability performance was conducted with 13 Czech cultivars of lucerne at four locations over a 2‐year period with the following aims: (a) to evaluate yield stability of varieties across different environments and (b) to calculate measurable benefits of variety selection in relation to the specific environment. The cultivar Vlasta was identified as the highest yielding cultivar (annual yield 16.0 t DM/ha), whereas the lowest yielding cv. Magda, Tereza and Oslava averaged around 14.9 t DM/ha. Effect of genotype × environment interaction (G × E) was two times higher than for genotype alone. Additive main effects and the multiplicative interaction (AMMI) model showed that the highest yielding cultivars may not be stable across environments. This study demonstrated further that significant yield improvement could be detected, even among a relatively homogenous group of domestic cultivars, and this was driven mainly by site productivity: the improvement was +10% in low‐yielding sites, compared with +3% in high‐yielding sites. Results highlight that advanced agronomy should also consider stability parameters such as AMMI stability value or superiority measures for forage crops in response to the challenges associated with climate change.

  • Effects of sowing methods and seeding rates on growth and yield characteristics of phasey bean (Macroptilium lathyroides)
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-10-02
    Manabu Tobisa; Yutaka Nakano

    This study was conducted to investigate the effects of sowing methods (broadcast or row sowing) and seeding rate (0.5, 1.0, 2.0 or 3.0 g/m2) on growth, yield characteristics, and forage quality of phasey bean (Macroptilium lathyroides (L.) Urb.) cv. “Murray”). Experiments were carried out in 2002 and 2003. Sowing method affected dry‐matter yield (DMY): broadcast sowing resulted in higher DMY than row sowing in 2002, and during the first harvest in 2003. Dry‐matter digestibility (DMD) and crude protein (CP) concentration were not influenced by the sowing method, except when DMD and CP of the broadcast sowing treatment increased as the plant weight increased. Contrary to expectation, seeding rate did not affect leaf area index, DMY, DMD, CP, digestible dry‐matter yield or CP yield. Even the lowest seeding rate did not influence the yield and forage quality of phasey bean, compared with the recommended higher seeding rate.

  • Stem elongation in Pennisetum purpureum results from a fixed pattern of vegetative development potentially enhanced by the initiation of flowering
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-04
    Guilherme Portes Silva; Sila Carneiro da Silva; Abraham Escobar‐Guttiérrez; Gilles Lemaire; Gaëtan Louarn

    The characterization of stem elongation is of fundamental importance in C4 tropical grasses as it affects forage quality and determines optimal management practices. The objectives of this study were to analyse the determinants of stem elongation and leaf area production in shoots of Pennisetum purpureum cv. Napier (elephant grass) using unstressed isolated plants. Three experiments were conducted in Brazil during the spring, summer and autumn seasons. Regular measurements of leaf and pseudostem length were performed on the main and primary axes. Ten destructive measurements were also performed during each experiment to monitor apical meristem height, internode length and the number of initiated leaves. The onset of stem elongation occurred at the same vegetative stage (i.e., appearance of leaf 13) irrespective of the seasons and experiments. The first internode to elongate belonged to phytomer 8, and a constant lag of five phyllochrons was systematically observed between internode production and its rapid elongation period. Higher stem and internode elongation rates were observed during the reproductive phase (autumn) versus the vegetative phase (summer and spring group). Maximal internode length reached 8–10 cm in summer and spring and 20 cm in autumn, at approximately phytomers 12–13. A similar pattern was reported for all primary axes irrespective of the experiments, the position of the first internode to elongate descending regularly down the main axis. These results provide key elements to predict the onset of stem elongation in the field from simple measurements. They could contribute to improving crop models for perennial tropical C4 grasses.

  • Chloris gayana Kunth under different defoliation regimes. Morphogenesis, sward structure and leaf area index
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-11-06
    María Soledad Ruolo; Héctor Eduardo Pérez; Adriana Mabel Rodriguez

    Subtropical pastures are an important alternative to increase forage yields to fulfil cattle nutritional requirements. Despite the increasing expansion of these pastures in the semiarid subtropical region of Argentina, there is very little information about their responses to grazing management. The aim of this study was to evaluate the effect of different defoliation regimes on morphogenesis, sward structure and leaf area index of one of the most expanded forage species in this region, Chloris gayana Kunth. A combination of two defoliation frequencies (300 and 500 GDD) and two defoliation intensities (1 and 3 green stubble leaves) was compared by a controlled experiment that comprised 1,500 GDD. Defoliation frequency significantly affected leaf elongation rate (LER) and leaf area index (LAI). Under the high defoliation frequency, LER and LAI resulted almost half than under low defoliation frequency (0.34 ± 0.08 vs. 0.67 ± 0.08 mm·tiller−1·GDD−1; 8.31 ± 2.27 m2/m2 vs. 13.27 ± 1.59 m2/m2, at 300 or 500 GDD respectively), regardless of the intensity. Defoliation frequency or intensity did not affect leaf appearance rate, leaf lifespan, leaf size, number of green leaves per tiller nor tiller density at the end of the experiment. We conclude that to maintain high LER and LAI in Chloris gayana Kunth cv. Épica INTA‐Pemán pastures, defoliation frequency could be of 500 GDD. Since leaf lifespan was 415 ± 110 GDD, under this defoliation frequency, a maximum accumulation of green leaf tissues with very little dead tissues may be achieved.

  • Does the "high sugar" trait of perennial ryegrass cultivars express under temperate climate conditions?
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-10-11
    M Jordana Rivero,Oscar A Balocchi,Cristian J Moscoso,Juan Agustín Siebald,Fabián Lukas Neumann,Don Meyer,Michael R F Lee

    The objective was to evaluate water-soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m2 each, three blocks): four PRG cultivars (diploid standard cultivar, "2nSt"; tetraploid standard cultivar, "4nSt"; diploid high sugar cultivar developed in New Zealand, "2nHSNZ"; and tetraploid high sugar cultivar developed in Europe, "4nHSEU") and two agronomic managements ("favourable," defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha-1 year-1; "unfavourable," defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha-1 year-1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12-month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the "high sugar" trait, where a genetic × environment interaction might be operating.

  • A review of our current understanding of parasite survival in silage and stored forages, with a focus on Fasciola hepatica metacercariae.
    Grass Forage Sci. (IF 1.814) Pub Date : 2019-06-28
    Bethan C John,David R Davies,Diana J L Williams,Jane E Hodgkinson

    Fasciola hepatica, the parasitic liver fluke, is a re-emerging zoonotic infection and an important cause of morbidity and mortality in ruminant livestock worldwide. A significant animal welfare concern, fasciolosis also has a detrimental impact on food security, with the effects of sub-clinical infection on growth rate and milk yield estimated to cost the UK cattle industry £40.4 million annually. It is understood that up to 50% of infective F. hepatica metacercariae may overwinter on pasture and remain viable to infect grazing livestock the following spring. However, the infection risk posed by feeding grass silage to livestock remains largely unknown as the majority of previous studies are outdated in both experimental design and analysis of ensiled metacercariae viability. Anecdotal reports of fasciolosis outbreaks in housed livestock have reignited interest in F. hepatica metacercariae survival during modern ensiling processes and more importantly if they retain viability within stored forages. Consequently, a comprehensive review of the available literature is required in order to identify knowledge gaps and highlight future research opportunities regarding the role of silage in the transmission of F. hepatica.

  • Potential of legume-based grassland-livestock systems in Europe: a review.
    Grass Forage Sci. (IF 1.814) Pub Date : 2014-06-01
    A Lüscher,I Mueller-Harvey,J F Soussana,R M Rees,J L Peyraud

    European grassland-based livestock production systems face the challenge of producing more meat and milk to meet increasing world demands and to achieve this using fewer resources. Legumes offer great potential for achieving these objectives. They have numerous features that can act together at different stages in the soil-plant-animal-atmosphere system, and these are most effective in mixed swards with a legume proportion of 30-50%. The resulting benefits include reduced dependence on fossil energy and industrial N-fertilizer, lower quantities of harmful emissions to the environment (greenhouse gases and nitrate), lower production costs, higher productivity and increased protein self-sufficiency. Some legume species offer opportunities for improving animal health with less medication, due to the presence of bioactive secondary metabolites. In addition, legumes may offer an adaptation option to rising atmospheric CO2 concentrations and climate change. Legumes generate these benefits at the level of the managed land-area unit and also at the level of the final product unit. However, legumes suffer from some limitations, and suggestions are made for future research to exploit more fully the opportunities that legumes can offer. In conclusion, the development of legume-based grassland-livestock systems undoubtedly constitutes one of the pillars for more sustainable and competitive ruminant production systems, and it can be expected that forage legumes will become more important in the future.

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上海纽约大学William Glover