Department of Agricultural Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Alta Genetics Inc., Balzac, AB, T4B 2T3, Canada.
Theriogenology. 2020 Jun;149:117-122. doi: 10.1016/j.theriogenology.2020.03.026. Epub 2020 Mar 24.
The objectives of this study were to (1) characterize the variability for sire's predicted transmitting ability (PTA) for daughter's pregnancy rate (DPR) and cow conception rate (CCR), (2) determine the relationships among sire's PTA for DPR, sire's PTA for CCR, daughter's parity, and daughter's 305-d mature-equivalent (ME) milk production, and (3) evaluate the associations among sire's PTA for DPR and CCR and daughter's reproductive performance [pregnancy to first artificial insemination (P/AI), pregnancy by 150 d in milk (PR150) and pregnancy loss (PL) after first AI] in Canadian Holstein cows. The data were obtained from 822 lactating Holstein cows from 10 commercial dairy herds located in Alberta. Overall mean (range) for sire's PTA for DPR and CCR was -0.09 (-9.6 to 8.2) and -0.05 (-9.9 to 7.4), respectively. Sire's PTA for DPR was strongly and positively associated with sire's PTA for CCR (r = 0.89; P < 0.01). Sire's PTA for DPR and CCR were weakly and negatively associated with parity (r = -0.15 and -0.17, respectively; P < 0.01); however, the amount of phenotypic variation in sire's PTA for DPR and CCR explainable by parity was small (coefficient of determination; R = 0.02). The daughter's 305-d ME milk production tended to be weakly but positively associated with sire's PTA for DPR (r = 0.06; P = 0.07) and CCR (r = 0.06; P = 0.10); however, the amount of phenotypic variation in daughter's 305-d ME milk production explainable by changes in sire's PTA for DPR or CCR was small (R = 0.004 and 0.003, respectively). Overall P/AI, PR150 and PL were 38, 65 and 12%, respectively. Sire's PTA for DPR tended to be associated with P/AI (P = 0.08) but was significantly associated with PR150 (P = 0.03). For every unit increase in sire's PTA for DPR, the estimated probabilities for P/AI and PR150 increased by 6.2 and 7.5%, respectively. Sire's PTA for CCR was not associated with P/AI or PR150. Neither sire's PTA for DPR nor CCR were associated with PL. In summary, sire's PTA for DPR and CCR were highly variable and positively correlated. Sire's PTA for DPR was associated with daughter's P/AI and PR150, but sire's PTA for CCR was not associated with any of the measured reproductive outcomes. Therefore, selecting sires with high PTA for DPR has the potential to improve the reproductive efficiency of Canadian dairy herds.
（1）描述 sire 预测繁殖力（PTA）对女儿妊娠率（DPR）和奶牛受胎率（CCR）的变异性；（2）确定 sire 的 DPR 和 CCR PTA 与女儿胎次、305 天成熟当量（ME）产奶量之间的关系；（3）评估 sire 的 DPR 和 CCR PTA 与加拿大荷斯坦奶牛繁殖性能[首次人工授精（AI）前怀孕（P/AI）、泌乳 150 天怀孕（PR150）和 AI 后怀孕损失（PL）]之间的关系。数据来自加拿大阿尔伯塔省 10 个商业奶牛场的 822 头泌乳荷斯坦奶牛。 sire 的 DPR 和 CCR PTA 的总体平均值（范围）分别为-0.09（-9.6 至 8.2）和-0.05（-9.9 至 7.4）。 sire 的 DPR PTA 与 CCR PTA 呈强正相关（r=0.89；P<0.01）。 sire 的 DPR 和 CCR PTA 与胎次呈弱负相关（r=-0.15 和-0.17，分别；P<0.01）；然而， sire 的 DPR 和 CCR PTA 中由胎次解释的表型变异量很小（决定系数；R=0.02）。女儿的 305 天 ME 产奶量与 sire 的 DPR PTA 呈弱正相关（r=0.06；P=0.07）和 CCR PTA（r=0.06；P=0.10）；然而，由 sire 的 DPR 或 CCR PTA 变化解释的女儿 305 天 ME 产奶量的表型变异量很小（R=0.004 和 0.003，分别）。总的 P/AI、PR150 和 PL 分别为 38%、65%和 12%。 sire 的 DPR PTA 与 P/AI 呈正相关（P=0.08），但与 PR150 显著相关（P=0.03）。 sire 的 DPR PTA 每增加 1 个单位，P/AI 和 PR150 的估计概率分别增加 6.2%和 7.5%。 sire 的 CCR PTA 与 P/AI 或 PR150 无关。 sire 的 DPR 和 CCR PTA 均与 PL 无关。总之， sire 的 DPR 和 CCR PTA 高度可变且呈正相关。 sire 的 DPR PTA 与女儿的 P/AI 和 PR150 相关，但 sire 的 CCR PTA 与任何测量的繁殖结果均不相关。因此，选择具有高 DPR PTA 的 sire 有潜力提高加拿大奶牛场的繁殖效率。
