Linear models that are commonly used to predict breeding values in livestock species consider paternal influence solely as a genetic effect. However, emerging evidence in several species suggests the potential effect of non-genetic semen-mediated paternal effects on offspring phenotype. This study contributes to such research by analyzing the extent of non-genetic paternal effects on the performance of Holstein, Montbéliarde, and Normande dairy cows. Insemination data, including semen Batch Identifier (BI, a combination of bull identification and collection date), was associated with various traits measured in cows born from the insemination. These traits encompassed stature, milk production (milk, fat, and protein yields), udder health (somatic cell score and clinical mastitis), and female fertility (conception rates of heifers and cows). We estimated (1) the effects of age at collection and heat stress during spermatogenesis, and (2) the variance components associated with BI or Weekly aggregated BI (WBI). Overall, the non-genetic paternal effect estimates were small and of limited biological importance. However, while heat stress during spermatogenesis did not show significant associations with any of the traits studied in daughters, we observed significant effects of bull age at semen collection on the udder health of daughters. Indeed, cows born from bulls collected after 1500 days of age had higher somatic cell scores compared to those born from bulls collected at a younger age (less than 400 days old) in both Holstein and Normande breeds (+ 3% and + 5% of the phenotypic mean, respectively). In addition, across all breeds and traits analyzed, the estimates of non-genetic paternal variance were consistently low, representing on average 0.13% and 0.09% of the phenotypic variance for BI and WBI, respectively (ranging from 0 to 0.7%). These estimates did not significantly differ from zero, except for milk production traits (milk, fat, and protein yields) in the Holstein breed and protein yield in the Montbéliarde breed when WBI was considered. Our findings indicate that non-genetic paternal information transmitted through semen does not substantially influence the offspring phenotype in dairy cattle breeds for routinely measured traits. This lack of substantial impact may be attributed to limited transmission or minimal exposure of elite bulls to adverse conditions.

中文翻译：

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研究父亲年龄、父亲热应激和非遗传父亲变异对奶牛表型的影响


通常用于预测牲畜品种育种值的线性模型将父系影响仅视为遗传效应。然而，几个物种的新证据表明，非遗传精液介导的父系效应对后代表型具有潜在影响。本研究通过分析非遗传父本对荷斯坦奶牛、蒙贝利亚德奶牛和诺曼德奶牛生产性能的影响程度，为此类研究做出了贡献。授精数据，包括精液批次标识符（BI，公牛识别和采集日期的组合），与授精所生奶牛的各种性状相关。这些性状包括身材、产奶量（牛奶、脂肪和蛋白质产量）、乳房健康（体细胞评分和临床乳腺炎）和女性生育力（小母牛和奶牛的受孕率）。我们估计了 (1) 采集年龄和精子发生过程中热应激的影响，以及 (2) 与 BI 或每周聚合 BI (WBI) 相关的方差分量。总体而言，非遗传父系效应估计值很小，生物学重要性有限。然而，虽然精子发生过程中的热应激并未显示出与女儿身上研究的任何性状存在显着关联，但我们观察到精液采集时公牛年龄对女儿乳房健康的显着影响。事实上，在荷斯坦和诺曼底品种中，1500 天后收集的公牛所生的奶牛，与年龄较小（小于 400 天）收集的公牛所生的奶牛相比，具有更高的体细胞分数（+ 3% 和 + 5%）。分别为表型平均值）。此外，在分析的所有品种和性状中，非遗传父系方差的估计值始终较低，平均为 0.13% 和 0。BI 和 WBI 的表型方差分别为 09%（范围从 0 到 0.7%）。这些估计与零没有显着差异，除了荷斯坦品种的产奶性状（牛奶、脂肪和蛋白质产量）和蒙贝利亚德品种的蛋白质产量（当考虑 WBI 时）。我们的研究结果表明，通过精液传递的非遗传父系信息不会对奶牛品种中常规测量性状的后代表型产生实质性影响。缺乏实质性影响可能是由于传播有限或精英公牛暴露在不利条件下的程度极低。