宁夏地区荷斯坦牛乳房性状的遗传参数估计和主成分分析

旨在评估宁夏地区荷斯坦牛乳房性状的遗传水平。本研究使用DMU（v6.0）软件的AI-REML模块结合EM算法并配合多性状动物模型对宁夏地区12 415头荷斯坦牛，包括111 735个观察值的9个乳房性状进行遗传参数估计，运用主成分分析法（PCA）探讨构象性状之间的关系。结果表明，宁夏地区荷斯坦牛乳房性状遗传力处于中等偏低水平，乳房深度遗传力值为0.242，乳房质地为0.080，悬韧带为0.183，前乳房附着为0.230，前乳头位置为0.231，前乳头长度为0.173，后乳房高为0.272，后乳房宽为0.378，后乳头位置为0.169。各性状遗传相关范围为-0.277~0.706，表型相关范围为-0.084~0.316。研究共筛选出特征值≥1的4个主成分，占总方差的64.19%，且9个乳房性状在前3个主成分中已全部体现，荷载系数均在0.4以上。本研究通过对宁夏地区奶牛DHI数据的深入挖掘和遗传参数估计，准确地把握了宁夏奶牛群体的结构特征，对于奶牛的选种选配和育种规划具有重要意义。

Genetic Parameter Estimates and Principal Component Analysis for Udder Traits of Holstein Cattle in Ningxia

This study aimed to evaluate the genetic level of the udder traits of Holstein cattle in Ningxia. The DMU software, the DMUAI module AI-REML, the EM algorithm and multi-trait animal models were used to estimate the genetic parameters of 12 415 Holstein cows in Ningxia, including 111 735 observed values of 9 udder traits. The principal component analysis was applied to explore the relationship between the conformation traits. The results showed that heritability of udder traits of Holstein cattle in Ningxia was at a moderate to inferior level: the values were 0.242 for udder depth, 0.080 for udder texture, 0.183 for median suspensory, 0.230 for fore udder attachment, 0.231 for fore teat placement, 0.173 for fore teat length, 0.272 for rear attachment height, 0.378 for rear attachment width and 0.169 for rear teat placement, respectively. The genetic correlation coefficients ranged from -0.277 to 0.706, while the phenotypic cor-relation coefficients ranged from -0.084 to 0.316. Furthermore, we selected 4 principal components with eigenvalues ≥ 1, 64.19% of the total variance. In addition, all 9 udder traits were reflected in the first 3 principal components, and all loaded coefficients were > 0.4. The present in-depth Dairy Herd Improvement data mining and genetic parameter estimation revealed the characteristics of Ningxia Holstein dairy cow population structure, which may greatly facilitate the design and execution of dairy cow breeding programs.