Longitudinal records of temperament can be used for assessing behavioral plasticity, such as aptness to learn, memorize, or change behavioral responses based on affective state. In this study, we evaluated the phenotypic and genomic background of North American Angus cow temperament measured throughout their lifetime around the weaning season, including the development of a new indicator trait termed docility-based learning and behavioral plasticity. The analyses included 273,695 and 153,898 records for yearling (YT) and cow at weaning (CT) temperament, respectively, 723,248 animals in the pedigree, and 8784 genotyped animals. Both YT and CT were measured when the animal was loading into/exiting the chute. Moreover, CT was measured around the time in which the cow was separated from her calf. A random regression model fitting a first-order Legendre orthogonal polynomial was used to model the covariance structure of temperament and to assess the learning and behavioral plasticity (i.e., slope of the regression) of individual cows. This study provides, for the first time, a longitudinal perspective of the genetic and genomic mechanisms underlying temperament, learning, and behavioral plasticity in beef cattle. CT measured across years is heritable (0.38–0.53). Positive and strong genetic correlations (0.91–1.00) were observed among all CT age-group pairs and between CT and YT (0.84). Over 90% of the candidate genes identified overlapped among CT age-groups and the estimated effect of genomic markers located within important candidate genes changed over time. A small but significant genetic component was observed for learning and behavioral plasticity (heritability = 0.02 ± 0.002). Various candidate genes were identified, revealing the polygenic nature of the traits evaluated. The pathways and candidate genes identified are associated with steroid and glucocorticoid hormones, development delay, cognitive development, and behavioral changes in cattle and other species. Cow temperament is highly heritable and repeatable. The changes in temperament can be genetically improved by selecting animals with favorable learning and behavioral plasticity (i.e., habituation). Furthermore, the environment explains a large part of the variation in learning and behavioral plasticity, leading to opportunities to also improve the overall temperament by refining management practices. Moreover, behavioral plasticity offers opportunities to improve the long-term animal and handler welfare through habituation.

中文翻译：

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揭示北美安格斯牛行为可塑性和气质的表型和基因组背景

气质的纵向记录可用于评估行为可塑性，例如学习、记忆或根据情感状态改变行为反应的能力。在这项研究中，我们评估了北美安格斯奶牛在断奶季节前后整个生命周期中测量的表型和基因组背景，包括一种称为基于温顺学习和行为可塑性的新指标性状的发展。分析分别包括 273,695 条和 153,898 条一岁 (YT) 和断奶奶牛 (CT) 气质记录、系谱中的 723,248 头动物和 8784 头基因分型动物。YT 和 CT 均在动物装入/离开滑槽时进行测量。此外，CT 是在母牛与小牛分开的前后测量的。拟合一阶勒让德正交多项式的随机回归模型用于模拟气质的协方差结构，并评估个体奶牛的学习和行为可塑性（即回归斜率）。这项研究首次提供了肉牛气质、学习和行为可塑性的遗传和基因组机制的纵向视角。跨年测量的 CT 是可遗传的 (0.38–0.53)。在所有 CT 年龄组对之间以及 CT 和 YT 之间 (0.84) 观察到正强遗传相关性 (0.91–1.00)。超过 90% 的候选基因在 CT 年龄组之间重叠，并且位于重要候选基因内的基因组标记的估计效果随时间而变化。在学习和行为可塑性方面观察到一个小但重要的遗传成分（遗传力 = 0.02 ± 0.002）。鉴定了各种候选基因，揭示了所评估性状的多基因性质。确定的途径和候选基因与类固醇和糖皮质激素、发育迟缓、认知发育以及牛和其他物种的行为变化有关。奶牛的气质具有很强的遗传性和可重复性。通过选择具有良好学习和行为可塑性（即习惯）的动物，可以从基因上改善气质的变化。此外，环境解释了学习和行为可塑性的很大一部分差异，从而有机会通过完善管理实践来改善整体气质。而且，