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The effects of energy metabolism variables on feed efficiency in respiration chamber studies with lactating dairy cows.
Journal of Dairy Science ( IF 3.5 ) Pub Date : 2020-06-10 , DOI: 10.3168/jds.2020-18259
A Guinguina 1 , T Yan 2 , A R Bayat 3 , P Lund 4 , P Huhtanen 1
Affiliation  

The objective of the present study was to investigate factors related to variation in feed efficiency (FE) among cows. Data included 841 cow/period observations from 31 energy metabolism studies assembled across 3 research stations. The cows were categorized into low-, medium-, and high-FE groups according to residual feed intake (RFI), residual energy-corrected milk (RECM), and feed conversion efficiency (FCE). Mixed model regression was conducted to identify differences among the efficiency groups in animal and energy metabolism traits. Partial regression coefficients of both RFI and RECM agreed with published energy requirements more closely than cofficients derived from production experiments. Within RFI groups, efficient (Low-RFI) cows ate less, had a higher digestibility, produced less methane (CH4) and heat, and had a higher efficiency of metabolizable energy (ME) utilization for milk production. High-RECM (most efficient) cows produced 6.0 kg/d more of energy-corrected milk (ECM) than their Low-RECM (least efficient) contemporaries at the same feed intake. They had a higher digestibility, produced less CH4 and heat, and had a higher efficiency of ME utilization for milk production. The contributions of improved digestibility, reduced CH4, and reduced urinary energy losses to increased ME intake at the same feed intake were 84, 12, and 4%, respectively. For both RFI and RECM analysis, increased metabolizability contributed to approximately 35% improved FE, with the remaining 65% attributed to the greater efficiency of utilization of ME. The analysis within RECM groups suggested that the difference in ME utilization was mainly due to the higher maintenance requirement of Low-RECM cows compared with Medium- and High-RECM cows, whereas the difference between Medium- and High-RECM cows resulted mainly from the higher efficiency of ME utilization for milk production in High-RECM cows. The main difference within FCE (ECM/DMI) categories was a greater (8.2 kg/d) ECM yield at the expense of mobilization in High-FCE cows compared with Low-FCE cows. Methane intensity (CH4/ECM) was lower for efficient cows than for inefficient cows. The results indicated that RFI and RECM are different traits. We concluded that there is considerable variation in FE among cows that is not related to dilution of maintenance requirement or nutrient partitioning. Improving FE is a sustainable approach to reduce CH4 production per unit of product, and at the same time improve the economics of milk production.



中文翻译:

在泌乳奶牛的呼吸室研究中,能量代谢变量对饲料效率的影响。

本研究的目的是调查与母牛饲料效率(FE)变化有关的因素。数据包括来自3个研究站的31项能量代谢研究的841头母牛/期间观测值。根据残余饲料摄入量(RFI),残余能量校正乳(RECM)和饲料转化效率(FCE)将母牛分为低,中和高FE组。进行了混合模型回归,以确定动物和能量代谢性状在效率组之间的差异。与生产实验得出的系数相比,RFI和RECM的部分回归系数与已公布的能源需求更加吻合。在RFI组中,高效(Low-RFI)奶牛吃得少,消化率更高,产生的甲烷更少(CH 4)和热量,并且在牛奶生产中具有更高的代谢能(ME)利用效率。在相同的采食量下,高RECM(效率最高)的母牛比同期Low-RECM(效率最低)的母牛生产的能量校正奶(ECM)多6.0 kg / d。它们具有较高的消化率,产生的CH 4和热量较少,并且在乳汁生产中利用ME的效率更高。改善消化率,减少CH 4的贡献,而在相同采食量下增加ME采食量减少的尿能损失分别为84%,12%和4%。对于RFI和RECM分析,新陈代谢的增加大约使FE改善了35%,其余的65%归因于ME的利用效率更高。RECM组内的分析表明,ME利用率的差异主要是由于低RECM奶牛与中,高RECM奶牛相比需要更高的维持需求,而中高RECM奶牛之间的差异主要是由于在高RECM奶牛中提高牛奶利用ME的效率。FCE(ECM / DMI)类别之间的主要区别在于,与低FCE母牛相比,高FCE母牛的动员产量更高(8.2 kg / d)。甲烷强度(CH4 / ECM)对于低效奶牛而言要比低效奶牛低。结果表明,RFI和RECM是不同的性状。我们得出的结论是,母牛之间的FE差异很大,与维持需求的稀释或养分分配无关。改善FE是减少单位产品中CH 4产量的可持续方法,同时也提高了牛奶生产的经济性。

更新日期:2020-08-18
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