Gonzalez-Recio O, Pryce J E, Haile-Mariam M, Hayes B J
Biosciences Research Division, Department of Environment and Primary Industries, Agribio, 5 Ring Road, Bundoora, VIC 3083, Australia; Dairy Futures Cooperative Research Centre, Bundoora, VIC 3083, Australia.
Biosciences Research Division, Department of Environment and Primary Industries, Agribio, 5 Ring Road, Bundoora, VIC 3083, Australia; Dairy Futures Cooperative Research Centre, Bundoora, VIC 3083, Australia; La Trobe University, Bundoora, VIC 3083, Australia.
J Dairy Sci. 2014;97(6):3883-93. doi: 10.3168/jds.2013-7515. Epub 2014 Mar 27.
The economic benefit of expanding the Australian Profit Ranking (APR) index to include residual feed intake (RFI) was evaluated using a multitrait selection index. This required the estimation of genetic parameters for RFI and genetic correlations using single nucleotide polymorphism data (genomic) correlations with other traits. Heritabilities of RFI, dry matter intake (DMI), and all the traits in the APR (milk, fat, and protein yields; somatic cell count; fertility; survival; milking speed; and temperament), and genomic correlations between these traits were estimated using a Bayesian framework, using data from 843 growing Holstein heifers with phenotypes for DMI and RFI, and bulls with records for the other traits. Heritability estimates of DMI and RFI were 0.44 and 0.33, respectively, and the genomic correlation between them was 0.03 and nonsignificant. The genomic correlations between the feed-efficiency traits and milk yield traits were also close to zero, ranging between -0.11 and 0.10. Positive genomic correlations were found for DMI with stature (0.16) and with overall type (0.14), suggesting that taller cows eat more as heifers. One issue was that the genomic correlation estimates for RFI with calving interval (ClvI) and with body condition score were both unfavorable (-0.13 and 0.71 respectively), suggesting an antagonism between feed efficiency and fertility. However, because of the relatively small numbers of animals in this study, a large 95% probability interval existed for the genomic correlation between RFI and ClvI (-0.66, 0.36). Given these parameters, and a genetic correlation between heifer and lactating cow RFI of 0.67, inclusion of RFI in the APR index would reduce RFI by 1.76 kg/cow per year. Including RFI in the APR would result in the national Australian Holstein herd consuming 1.73 × 10(6) kg less feed, which is worth 0.55 million Australian dollars (A$) per year and is 3% greater than is currently possible to achieve. Other traits contributing to profitability, such as milk production and fertility, will also improve through selection on this index; for example, ClvI would be reduced by 0.53 d/cow per year, which is 96% of the gain for this trait that is achieved without RFI in the APR.
利用多性状选择指数评估了将澳大利亚利润排名（APR）指数扩展至纳入剩余采食量（RFI）的经济效益。这需要利用单核苷酸多态性数据（基因组）与其他性状的相关性来估计RFI的遗传参数和遗传相关性。使用贝叶斯框架，利用来自843头生长中的荷斯坦小母牛的DMI和RFI表型数据以及其他性状记录的公牛数据，估计了RFI、干物质采食量（DMI）以及APR中的所有性状（牛奶、脂肪和蛋白质产量；体细胞计数；繁殖力；存活率；挤奶速度；以及性情）的遗传力，以及这些性状之间的基因组相关性。DMI和RFI的遗传力估计值分别为0.44和0.33，它们之间的基因组相关性为0.03且不显著。饲料效率性状与牛奶产量性状之间的基因组相关性也接近于零，范围在-0.11至0.10之间。发现DMI与体高（0.16）和整体类型（0.14）存在正基因组相关性，这表明较高的母牛在小母牛阶段采食量更多。一个问题是，RFI与产犊间隔（ClvI）以及体况评分的基因组相关性估计均不理想（分别为-0.13和0.71），这表明饲料效率与繁殖力之间存在拮抗作用。然而，由于本研究中的动物数量相对较少，RFI与ClvI之间的基因组相关性存在较大的95%概率区间（-0.66，0.36）。鉴于这些参数，以及小母牛与泌乳母牛RFI之间的遗传相关性为0.67，将RFI纳入APR指数将使每头母牛每年的RFI降低1.76千克。将RFI纳入APR将使澳大利亚全国荷斯坦牛群每年少消耗1.73×10⁶千克饲料，价值55万澳元，比目前可能实现的节省量高出3%。通过对该指数进行选择，其他对盈利能力有贡献的性状，如牛奶产量和繁殖力，也将得到改善；例如，ClvI将每年降低0.53天/头，这是在APR中不纳入RFI时该性状所实现增益的96%。
