Animal and Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland.
J Anim Sci. 2011 Nov;89(11):3372-81. doi: 10.2527/jas.2011-3835. Epub 2011 Jun 16.
Most studies on feed efficiency in beef cattle have focused on performance in young animals despite the contribution of the cow herd to overall profitability of beef production systems. The objective of this study was to quantify, using a large data set, the genetic covariances between feed efficiency in growing animals measured in a performance-test station, and beef cow performance including fertility, survival, calving traits, BW, maternal weaning weight, cow price, and cull cow carcass characteristics in commercial herds. Feed efficiency data were available on 2,605 purebred bulls from 1 test station. Records on cow performance were available on up to 94,936 crossbred beef cows. Genetic covariances were estimated using animal and animal-dam linear mixed models. Results showed that selection for feed efficiency, defined as feed conversion ratio (FCR) or residual BW gain (RG), improved maternal weaning weight as evidenced by the respective genetic correlations of -0.61 and 0.57. Despite residual feed intake (RFI) being phenotypically independent of BW, a negative genetic correlation existed between RFI and cow BW (-0.23; although the SE of 0.31 was large). None of the feed efficiency traits were correlated with fertility, calving difficulty, or perinatal mortality. However, genetic correlations estimated between age at first calving and FCR (-0.55 ± 0.14), Kleiber ratio (0.33 ± 0.15), RFI (-0.29 ± 0.14), residual BW gain (0.36 ± 0.15), and relative growth rate (0.37 ± 0.15) all suggest that selection for improved efficiency may delay the age at first calving, and we speculate, using information from other studies, that this may be due to a delay in the onset of puberty. Results from this study, based on the estimated genetic correlations, suggest that selection for improved feed efficiency will have no deleterious effect on cow performance traits with the exception of delaying the age at first calving.
大多数关于肉牛饲料效率的研究都集中在幼畜的表现上，尽管牛群对牛肉生产系统的整体盈利能力有贡献。本研究的目的是使用大量数据集，量化在性能测试站测量的生长动物饲料效率的遗传协方差，以及包括繁殖力、存活率、产犊性状、体重、母本断奶体重、牛价和淘汰牛胴体特征在内的肉牛母牛性能在商业牛群中。在一个测试站，有 2605 头纯种公牛的饲料效率数据可用。关于母牛性能的记录可用于多达 94936 头杂交肉牛。使用动物和动物- dam 线性混合模型估计遗传协方差。结果表明，选择饲料效率，定义为饲料转化率（FCR）或剩余体重增益（RG），改善了母本断奶体重，这可以从遗传相关系数分别为-0.61 和 0.57 得到证明。尽管残留饲料摄入量（RFI）在表型上与体重无关，但 RFI 与牛体重之间存在负遗传相关关系（-0.23；尽管 0.31 的 SE 较大）。饲料效率性状与繁殖力、产犊困难或围产期死亡率均无相关性。然而，在首次产犊年龄与 FCR（-0.55±0.14）、克莱伯比率（0.33±0.15）、RFI（-0.29±0.14）、剩余体重增益（0.36±0.15）和相对生长率（0.37±0.15）之间估计的遗传相关表明，选择提高效率可能会延迟首次产犊年龄，我们推测，根据其他研究的信息，这可能是由于青春期的延迟。本研究基于估计的遗传相关，结果表明，选择提高饲料效率不会对母牛性能性状产生有害影响，除了延迟首次产犊年龄。
