The aim of this study was to estimate genetic parameters for lactation yields of milk (MY), fat (FY), protein (PY), and somatic cell score (SCS) of New Zealand dairy goats. The analysis used 64,604 lactation records from 23,583 does, kidding between 2004 and 2017, distributed in 21 flocks and representing 915 bucks. Estimates of genetic and residual (co) variances, heritabilities, and repeatabilities were obtained using a multiple-trait repeatability animal model. The model included the fixed effects of contemporary group (does kidding in the same flock and year), age of the doe (in years), and as covariates, kidding day, proportion of Alpine, Nubian, Toggenburg, and "unknown" breeds (Saanen was used as the base breed), and heterosis. Random effects included additive animal genetic and doe permanent environmental effects. Estimates of heritabilities were 0.25 for MY, 0.24 for FY, 0.24 for PY, and 0.21 for SCS. The phenotypic correlations between MY, FY, and PY ranged from 0.90 to 0.96, and the genetic correlations ranged from 0.81 to 0.93. These results indicate lactation yield traits exhibit useful heritable variation and that multiple trait selection for these traits could improve milk revenue produced from successive generations of New Zealand dairy goats.

中文翻译：

---

新西兰奶山羊泌乳总产量、脂肪、蛋白质和体细胞评分的遗传参数。

本研究的目的是评估新西兰奶山羊泌乳量 (MY)、脂肪 (FY)、蛋白质 (PY) 和体细胞评分 (SCS) 的遗传参数。该分析使用了 23,583 头母牛的 64,604 条泌乳记录，从 2004 年到 2017 年开玩笑，分布在 21 个鸡群中，代表 915 头雄鹿。使用多性状可重复性动物模型获得遗传和残差 (co) 方差、遗传力和可重复性的估计值。该模型包括当代群体的固定效应（在同一年和同一群中开玩笑）、母鹿的年龄（以年为单位）以及作为协变量、开玩笑的日子、阿尔卑斯山、努比亚、吐根堡和“未知”品种的比例（以莎能为基础品种）和杂种优势。随机效应包括加性动物遗传效应和母鹿永久性环境效应。MY 的遗传力估计值为 0.25，FY 为 0.24，PY 为 0.24，SCS 为 0.21。MY、FY 和 PY 之间的表型相关性范围为 0.90 至 0.96，遗传相关性范围为 0.81 至 0.93。这些结果表明泌乳产量性状表现出有用的可遗传变异，并且对这些性状进行多性状选择可以提高新西兰奶山羊连续几代的产奶量。