Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, viale dell' Università 16 35020, Legnaro PD, Italy.
Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, viale dell' Università 16 35020, Legnaro PD, Italy.
J Dairy Sci. 2021 Jun;104(6):6832-6846. doi: 10.3168/jds.2020-19694. Epub 2021 Mar 25.
This study aimed to investigate the genetic and putative causal relationships between fertility traits [i.e., days open (DO) and calving rate (CR)] and milk quality, composition, and fatty acid contents (milk composition traits) in Holstein-Friesian, Brown Swiss, and Simmental cattle, using recursive models within a Bayesian framework. Trivariate animal models were run, each including one fertility trait, one milk composition trait, and, in all models, milk yield. The DO and CR data were merged with the test days closest to the insemination date for milk composition traits. After editing, 16,468 to 23,424 records for Holstein-Friesian, 23,424 to 46,660 for Brown Swiss, and 26,105 to 35,574 for Simmental were available for the analyses. Recursive animal models were applied to investigate the possible causal influences of milk composition traits on fertility and the genetic relationships among these traits. The results suggested a potential cause-and-effect relationship between milk composition traits and fertility traits, with the first trait influencing the latter. We also found greater recursive effects of milk composition traits on DO than on CR, the latter with some putative differences among breeds in terms of sensitivity. For instance, the putative causal effects of somatic cell score on CR (on the observed scale, %) varied from -0.96 to -1.39%, depending on the breed. Concerning fatty acids, we found relevant putative effects of C18:0 on CR, with estimates varying from -7.8 to -9.9%. Protein and casein percentages, and short-chain fatty acid showed larger recursive effects on CR, whereas fat, protein, and casein percentages, C16:0, C18:0, and long-chain fatty acid had larger effects on DO. The results obtained suggested that these milk traits could be considered as effective indicators of the effects of animal metabolic and physiological status on fertility.
本研究旨在使用贝叶斯框架内的递归模型，调查荷斯坦-弗里生牛、瑞士褐牛和西门塔尔牛的生育性状（即发情天数（DO）和配种率（CR））与牛奶质量、组成和脂肪酸含量（牛奶组成性状）之间的遗传和潜在因果关系。进行了三重动物模型分析，每个模型都包括一个生育性状、一个牛奶组成性状以及所有模型中的产奶量。发情天数和配种率数据与最接近牛奶组成性状授精日期的测试天数合并。编辑后，荷斯坦-弗里生牛有 16468 到 23424 条记录，瑞士褐牛有 23424 到 46660 条记录，西门塔尔牛有 26105 到 35574 条记录可用于分析。递归动物模型用于研究牛奶组成性状对生育力的可能因果影响以及这些性状之间的遗传关系。结果表明，牛奶组成性状与生育性状之间存在潜在的因果关系，前者影响后者。我们还发现，牛奶组成性状对发情天数的递归影响大于对配种率的影响，而后者在不同品种之间存在敏感性方面的差异。例如，体细胞评分对配种率的潜在因果效应（在观测尺度上，%）因品种而异，从-0.96 到-1.39%不等。关于脂肪酸，我们发现 C18:0 对 CR 有相关的潜在影响，估计值从-7.8 到-9.9%不等。蛋白质和酪蛋白百分比以及短链脂肪酸对 CR 的递归影响较大，而脂肪、蛋白质和酪蛋白百分比、C16:0、C18:0 和长链脂肪酸对 DO 的影响较大。所得结果表明，这些牛奶性状可以被视为动物代谢和生理状态对生育力影响的有效指标。
