The aim of this study was to investigate in Holstein cows the genetic basis of blood serum metabolites [i.e., total protein, albumin, globulin, albumin:globulin ratio (A:G), and blood β-hydroxybutyrate (BHB)], a set of milk phenotypes related to udder health, milk quality technological characteristics, and genetic relationships among them. Samples of milk were collected from 498 Holstein cows belonging to 28 herds. All animal welfare and milk phenotypes were assessed using standard analytical methodology. A set of Bayesian univariate and bivariate animal models was implemented via Gibbs sampling, and statistical inference was based on the marginal posterior distributions of parameters of concern. We observed a small additive genetic influence for serum albumin concentrations, moderate heritability (≥0.20) for total proteins, globulins, and A:G, and high heritability (0.37) for blood BHB. Udder health traits (somatic cell score, milk lactose, and milk pH) showed low or moderate heritabilities (0.15–0.20), whereas variations in milk protein fraction concentrations were confirmed as mostly under genetic control (heritability: 0.21–0.71). The moderate and high heritabilities observed for milk coagulation properties and curd firming modeling parameters provided confirmation that genetic background exerts a strong influence on the cheese-making ability of milk, largely due to genetic polymorphisms in the major milk protein genes. Blood BHB showed strong negative genetic correlations with globulins (−0.619) but positive correlations with serum albumin (0.629) and A:G (0.717), which suggests that alterations in the serum protein pattern and BHB blood levels are likely to be genetically related. Strong relationships were found between albumin and fat percentages (−0.894), between globulin and α_S2-CN (−0.610), and, to a lesser extent, between serum protein pattern and milk technological characteristics. Genetic relationships between blood BHB and traits related to udder health and milk quality and technological characteristics were mostly weak. This study provides evidence that there is exploitable additive genetic variation for traits related to animal health and welfare and throws light on the shared genetic basis of these traits and the phenotypes related to the quality and cheese-making ability of milk.

本研究的目的是研究荷斯坦奶牛血清代谢产物的遗传基础[即总蛋白，白蛋白，球蛋白，白蛋白：球蛋白比（A：G）和血液β-羟基丁酸酯（BHB）]。与乳房健康，牛奶品质有关的牛奶表型技术特征，以及它们之间的遗传关系。从498个属于28个牛群的荷斯坦奶牛那里采集了牛奶样品。使用标准分析方法评估所有动物福利和牛奶表型。通过吉布斯（Gibbs）采样实现了一组贝叶斯单变量和双变量动物模型，并且统计推断是基于关注参数的边际后验分布。我们观察到对血清白蛋白浓度有较小的累加遗传影响，对总蛋白，球蛋白和A：G的适度遗传性（≥0.20），对血液BHB的较高遗传性（0.37）。乳房健康特征（体细胞评分，牛奶乳糖，以及牛奶的pH值）显示出较低或中等的遗传力（0.15–0.20），而牛奶蛋白级分浓度的变化主要是在遗传控制下进行的（遗传力：0.21-0.71）。观察到的牛奶凝结特性和凝乳凝固模型参数的中度和高度遗传力提供了证实，遗传背景对牛奶的奶酪制造能力产生了强烈影响，这在很大程度上是由于主要牛奶蛋白基因的遗传多态性所致。血液中BHB与球蛋白的遗传相关性很强（-0.619），但与血清白蛋白（0.629）和A：G（0.717）的相关性正相关，这说明血清蛋白模式和BHB的改变血液水平可能与遗传有关。发现强有力的关系白蛋白和脂肪百分比（-0.894）之间，球蛋白和α之间_S2 -CN（-0.610），以及，在较小程度上，血清蛋白图案和牛奶技术特性之间。血液中BHB与与乳房健康，牛奶质量和技术特征相关的性状之间的遗传关系大多较弱。这项研究提供了证据，证明与动物健康和福利有关的性状存在可利用的加性遗传变异，并阐明了这些性状的共同遗传基础以及与牛奶的品质和干酪制造能力有关的表型。