Trujano Zuleica, Hidalgo Jorge, Gowane Gopal, Retallick Kelli, Garcia Andre, Lourenco Daniela, Misztal Ignacy
Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA.
Division of Animal Genetics and Breeding, ICAR-National Dairy Research Institute, Karnal 132001, India.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf158.
Genomic evaluation improves accuracy and enables shorter generation intervals, accelerating genetic changes, possibly strengthening the antagonism between performance and less-selected traits. Our objective was to evaluate the impact of genomic selection for performance on foot structure in Angus cattle. Variance component estimation was done under the Bayesian approach (variance components estimation [VCE]) with partial or no genotypes, and with a new method based on predictivity (PRED) using all genotypes, to examine changes in genetic parameters over time. The performance trait groups were growth (GT), carcass (carcass traits [CT]), ultrasound carcass (uCT), and marbling (MT). Foot structure traits (FT) were foot angle (FA) and claw set (CS). Genetic parameters through VCE over 5-yr intervals and using genotypes were obtained. From 2011 to 2015 to 2019 to 2022, changes in heritability were observed for CS (0.12 ± 0.01 to 0.16 ± 0.01), FA (0.18 ± 0.02 to 0.14 ± 0.01), carcass weight (0.30 ± 0.03 to 0.35 ± 0.04), marbling (0.43 ± 0.02 to 0.60 ± 0.04), and ultrasound backfat thickness (0.32 ± 0.01 to 0.38 ± 0.01). Changes in genetic correlations were found for CS-carcass weight (0.25 ± 0.15 to -0.04 ± 0.08), CS-rib eye area (0.20 ± 0.11 to -0.12 ± 0.08), and CS-weight at ultrasound scanning (0.12 ± 0.06 to 0.0 ± 0.03). For PRED, estimates from two 2-yr slices showed that most GT and uCT heritabilities were lower than those from the last VCE interval (e.g., birth weight: 0.34 vs. 0.26). In comparison, FT heritabilities were higher (e.g., CS: 0.16 vs. 0.29). In general, all genetic correlations from PRED ranged from -0.15 to 0.10, whereas the values were between -0.15 and 0.05 in the last interval based on VCE. The predictivity method provides updated genetic parameters for young animals, whereas VCE estimates refer to the base population. Including genotypes had a strong impact on some estimates. Our results indicate that heritability estimates in recent generations for strongly selected traits have decreased compared to older generations. However, genetic correlations between foot structure and performance traits have consistently remained close to zero, likely due to the differences in selection intensity between these traits. While no strong antagonistic correlations were found, selecting multiple traits is crucial to maintain conformation while improving performance. Since the population structure changes due to genetic or environmental factors, updating the genetic parameters is vital for achieving expected genetic gains.
基因组评估提高了准确性，并缩短了世代间隔，加速了遗传变化，这可能会增强生产性能与较少被选择性状之间的拮抗作用。我们的目标是评估安格斯牛基因组选择对生产性能的影响及其对蹄部结构的作用。采用贝叶斯方法（方差成分估计[VCE]），在有部分基因型或无基因型的情况下，以及使用一种基于预测性的新方法（PRED）并利用所有基因型来估计方差成分，以检验遗传参数随时间的变化。生产性能性状组包括生长（GT）、胴体（胴体性状[CT]）、超声胴体（uCT）和大理石花纹（MT）。蹄部结构性状（FT）为蹄角（FA）和蹄叉角度（CS）。通过VCE在5年间隔期并使用基因型获得了遗传参数。从2011年到2015年、再到2019年至2022年，观察到CS（0.12±0.01至0.16±0.01）、FA（0.18±0.02至0.14±0.01）、胴体重（0.30±0.03至0.35±0.04）、大理石花纹（0.43±0.02至0.60±0.04）以及超声背膘厚度（0.32±0.01至0.38±0.01）的遗传力发生了变化。发现CS与胴体重（0.25±0.15至 -0.04±0.08）、CS与肋眼面积（0.20±0.11至 -0.12±0.08）以及CS与超声扫描时体重（0.12±0.06至0.0±0.03）之间的遗传相关性发生了变化。对于PRED，来自两个2年时间段的估计表明，大多数GT和uCT的遗传力低于最后一个VCE间隔期的估计值（例如，出生体重：0.34对0.26）。相比之下，FT的遗传力更高（例如，CS：0.16对0.29）。总体而言，PRED的所有遗传相关性在 -0.15至0.10之间，而基于VCE的最后一个间隔期的值在 -0.15至0.05之间。预测性方法为幼龄动物提供了更新的遗传参数，而VCE估计值则针对基础群体。纳入基因型对一些估计值有很大影响。我们的结果表明，与较老的世代相比，近期世代中强选择性状的遗传力估计值有所下降。然而，蹄部结构与生产性能性状之间的遗传相关性一直保持接近零，这可能是由于这些性状之间选择强度的差异所致。虽然未发现强烈的拮抗相关性，但选择多个性状对于在提高生产性能的同时保持体型结构至关重要。由于群体结构因遗传或环境因素而发生变化，更新遗传参数对于实现预期的遗传进展至关重要。
