Snelling Warren M, Thallman R Mark, Spangler Matthew L, Kuehn Larry A
USDA-ARS, US Meat Animal Research Center, Clay Center, NE 68933, USA.
Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
Animals (Basel). 2022 Jul 7;12(14):1745. doi: 10.3390/ani12141745.
Programs for sustainable beef production are established, but the specific role of beef cows in these systems is not well defined. This work characterized cows for two traits related to sustainability, cow weight (CW) and cumulative weight weaned (WtW). Cow weight indicates nutrient requirements and enteric methane emissions. Cumulative weight weaned reflects reproductive performance and avoidance of premature culling for characteristics related to animal health, welfare, and worker safety. Both traits were evaluated with random regression models with records from a crossbred population representing 18 breeds that conduct US national cattle evaluations. The genomic REML analyses included additive and dominance components, with relationships among 22,776 animals constructed from genotypes of 181,286 potentially functional variants imputed from a low-pass sequence. Projected to 8 years of age, the additive heritability estimate for CW was 0.57 and 0.11 for WtW. Dominance heritability was 0.02 for CW and 0.19 for WtW. Many variants with significant associations with CW were within previously described quantitative trait loci (QTL) for growth-related production, meat, and carcass traits. Significant additive WtW variants were covered by QTL for traits related to reproduction and structural soundness. All breeds contributed to groups of cows with high and low total genetic values (additive + dominance effects) for both traits. The high WtW cows and cows above the WtW mean but below the CW mean had larger heterosis values and fewer bases in runs of homozygosity. The high additive heritability of CW and dominance effects on WtW indicate that breeding to improve beef cow sustainability should involve selection to reduce CW and mate selection to maintain heterosis and reduce runs of homozygosity.
可持续牛肉生产项目已经确立，但肉牛在这些系统中的具体作用尚未明确界定。这项研究针对与可持续性相关的两个性状对母牛进行了特征描述，即母牛体重（CW）和累计断奶体重（WtW）。母牛体重表明营养需求和肠道甲烷排放。累计断奶体重反映繁殖性能以及避免因与动物健康、福利和工人安全相关的特征而过早淘汰。利用随机回归模型对这两个性状进行了评估，数据来自一个代表18个品种的杂交群体，这些品种参与了美国全国牛的评估。基因组REML分析包括加性和显性成分，基于181,286个潜在功能变异的基因型构建了22,776头动物之间的关系，这些变异是通过低通量序列估算出来的。预测到8岁时，CW的加性遗传力估计值为0.57，WtW为0.11。CW的显性遗传力为0.02，WtW为0.19。许多与CW显著相关的变异位于先前描述的与生长相关的生产、肉质和胴体性状的数量性状位点（QTL）内。显著的加性WtW变异被与繁殖和结构健全性相关性状的QTL所覆盖。所有品种都对这两个性状的高和低总遗传值（加性 + 显性效应）的母牛群体有贡献。高WtW的母牛以及WtW高于均值但CW低于均值的母牛具有更大的杂种优势值和更少的纯合子连续片段。CW的高加性遗传力和WtW的显性效应表明，为提高肉牛可持续性进行育种应包括选择降低CW以及选择配偶以维持杂种优势并减少纯合子连续片段。
