USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT 59301, USA.
J Anim Sci. 2011 Dec;89(12):3917-23. doi: 10.2527/jas.2011-4124. Epub 2011 Jul 15.
Recent improvement in technologies for measuring individual feed intake has made possible the collection of data suitable for breed-wide genetic evaluation. The goals of this research were to estimate genetic parameters for components of feed efficiency and develop a prototype system for conducting a genetic evaluation of Angus cattle for feed intake. Weaning weight (WWT), postweaning BW gain (PGN), subcutaneous fat depth (SQF), and feed intake data were accumulated by the American Angus Association from a variety of cooperators and augmented with data collected for routine genetic evaluation of Angus cattle. The feed intake data were standardized (SFI, mean 0 and variance 1) within contemporary groups. Numbers of animals with observed phenotypes were 18,169, 7,107, 4,976, and 4,215 for WWT, PGN, SQF, and SFI, respectively. The 4-generation pedigree for animals with records contained 45,120 individuals. (Co)variance components were estimated with ASREML, fitting a 4-trait animal model with fixed contemporary groups for WWT, PGN, SQF, and SFI. Heritability estimates were 0.33 ± 0.03, 0.31 ± 0.04, 0.26 ± 0.04, and 0.42 ± 0.05 for direct genetic effects on WWT, PGN, SQF, and SFI, respectively. Genetic correlations of WWT and PGN with SFI were 0.40 ± 0.07 and 0.55 ± 0.10, respectively, and indicate their value as indicator traits in predicting EPD for feed intake. The genetic correlation of SQF and SFI was not different from 0. For all animals with a recorded feed intake phenotype, accuracy of their EPD for feed intake ranged from 0.16 to 0.64 with a mean of 0.26. However, 9,075 animals had an accuracy that was equal to or exceeded 0.2 for their feed intake EPD. Postanalysis calculation of measures of efficiency EPD was pursued. This work demonstrates the feasibility of conducting a national cattle evaluation for feed intake using indicator traits to reduce opportunity for selection bias, increase accuracy of the evaluation for a substantial number of animals, and ultimately facilitate calculation of selection indexes including feed intake.
最近在测量个体采食量的技术方面取得的进步使得能够收集适合于全品种遗传评估的数据。本研究的目的是估计饲料效率组成部分的遗传参数，并开发一种用于对安格斯牛进行采食量遗传评估的原型系统。断奶体重（WWT）、断奶后体重增益（PGN）、皮下脂肪厚度（SQF）和采食量数据由美国安格斯协会从各种合作者那里积累，并通过对安格斯牛的常规遗传评估收集的数据进行补充。采食量数据在当代群体内标准化（SFI，平均值为 0，方差为 1）。具有观察表型的动物数量分别为 18169、7107、4976 和 4215 用于 WWT、PGN、SQF 和 SFI。具有记录的动物的 4 代系谱包含 45120 个人。（共）方差分量用 ASREML 估计，拟合了一个具有固定当代群体的 4 个性状动物模型，用于 WWT、PGN、SQF 和 SFI。WWT、PGN、SQF 和 SFI 的直接遗传效应的遗传力估计值分别为 0.33 ± 0.03、0.31 ± 0.04、0.26 ± 0.04 和 0.42 ± 0.05。WWT 和 PGN 与 SFI 的遗传相关分别为 0.40 ± 0.07 和 0.55 ± 0.10，表明它们作为预测饲料摄入量 EPD 的指示性状具有价值。SQF 和 SFI 的遗传相关性与 0 无差异。对于具有记录的采食量表型的所有动物，其采食量 EPD 的准确性范围从 0.16 到 0.64，平均值为 0.26。然而，有 9075 头动物的采食量 EPD 准确性等于或超过 0.2。对效率 EPD 进行了后分析计算。这项工作证明了使用指示性状进行全国性牛饲料摄入量评估的可行性，这可以减少选择偏差的机会，提高大量动物评估的准确性，并最终有助于计算包括饲料摄入量在内的选择指数。
