Laboratory of Animal Genetics, Breeding, and Reproduction, Ministry of Agriculture of China, National Engineering Laboratory of Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
Beijing Dairy Center, Beijing, 100192, China.
J Dairy Sci. 2022 Aug;105(8):6749-6759. doi: 10.3168/jds.2021-21450. Epub 2022 Jul 13.
High mortality and involuntary culling rates cause great economic losses to the worldwide dairy cattle industry. However, there is low emphasis on wellness traits in replacement animals (dairy calves and replacement heifers) during their development stages in modern dairy cattle breeding programs. Therefore, the main objectives of this study were to estimate genetic parameters of wellness traits in replacement cattle (replacement wellness traits) and obtain their genetic correlations with 12 cow health and longevity traits in the Chinese Holstein population. Seven replacement wellness traits were analyzed, including birth weight, survival from 3 to 60 d (Sur1), survival from 61 to 365 d (Sur2), survival from 366 d to the first calving (Sur3), calf diarrhea, calf pneumonia, and calf serum total protein (STP). Single and bivariate animal models were employed to estimate (co)variance components using the data from 189,980 Holstein cattle. The genetic correlations between replacement wellness traits and cow longevity, health traits were calculated by employing bivariate models, including 6 longevity traits and 6 health traits (clinical mastitis, metritis, ketosis, displaced abomasum, milk fever, and hoof health or hoof disease). The estimated heritabilities (± SE) were 0.335 (± 0.008), 0.088 (± 0.005), 0.166 (± 0.006), 0.102 (±0 .006), 0.048 (± 0.003), 0.063 (± 0.004), and 0.170 (± 0.019) for birth weight, Sur1, Sur2, Sur3, pneumonia, diarrhea, and STP, respectively. The majority of the genetic correlations among the 7 replacement wellness traits were negligible. The genetic correlations among Sur1, Sur2, and Sur3 ranged from 0.112 (Sur1 and Sur3) to 0.445 (Sur1 and Sur2) when fitting a linear model (estimates in the observed scale), and from 0.560 (Sur1 and Sur3) to 0.773 (Sur1 and Sur2) when fitting a threshold model (estimates in the liability scale). The genetic correlations between replacement wellness and cow longevity were low (absolute value lower than 0.30), but some of them were significantly different from zero. Compared with other replacement wellness traits, Sur3 and STP had relatively high genetic correlations with cow longevity. Replacement wellness traits are heritable and can be improved through direct genetic and genomic selection. The results from the current study will contribute for better balancing dairy cattle breeding goals to genetically improve dairy cattle wellness in the period from birth to first calving.
高死亡率和非自愿淘汰率给全球奶牛养殖业造成了巨大的经济损失。然而，在现代奶牛养殖计划中，对后备动物（奶牛犊牛和后备小母牛）的健康性状的重视程度较低。因此，本研究的主要目的是估计后备牛（后备牛健康性状）的健康性状的遗传参数，并获得其与中国荷斯坦牛的 12 个奶牛健康和长寿性状的遗传相关性。分析了 7 个后备牛健康性状，包括初生重、3 至 60 日龄存活率（Sur1）、61 至 365 日龄存活率（Sur2）、366 日龄至首次产犊存活率（Sur3）、犊牛腹泻、犊牛肺炎和犊牛血清总蛋白（STP）。利用 189980 头荷斯坦牛的数据，采用单变量和双变量动物模型估计（协）方差分量。利用双变量模型计算了后备牛健康性状与奶牛长寿和健康性状之间的遗传相关性，包括 6 个长寿性状和 6 个健康性状（临床乳腺炎、子宫内膜炎、酮病、真胃移位、产后瘫痪和蹄部健康或蹄病）。估计的遗传力（± SE）分别为 0.335（± 0.008）、0.088（± 0.005）、0.166（± 0.006）、0.102（±0.006）、0.048（± 0.003）、0.063（± 0.004）和 0.170（± 0.019），分别对应初生重、Sur1、Sur2、Sur3、肺炎、腹泻和 STP。7 个后备牛健康性状之间的大多数遗传相关性可以忽略不计。Sur1、Sur2 和 Sur3 之间的遗传相关性在拟合线性模型时为 0.112（Sur1 和 Sur3）至 0.445（Sur1 和 Sur2）（估计值在观察尺度上），在拟合阈值模型时为 0.560（Sur1 和 Sur3）至 0.773（Sur1 和 Sur2）（估计值在隶属尺度上）。后备牛健康性状与奶牛长寿之间的遗传相关性较低（绝对值低于 0.30），但其中一些与零值有显著差异。与其他后备牛健康性状相比，Sur3 和 STP 与奶牛长寿的遗传相关性较高。后备牛健康性状具有遗传性，可以通过直接遗传和基因组选择进行改良。本研究的结果将有助于更好地平衡奶牛养殖目标，以提高从出生到首次产犊期间奶牛的健康水平。
