Department of Animal Science, The Pennsylvania State University, University Park 16802.
Department of Animal Science, The Pennsylvania State University, University Park 16802.
J Dairy Sci. 2021 Feb;104(2):2018-2026. doi: 10.3168/jds.2020-19080. Epub 2020 Dec 23.
Passive transfer of immunity is important for calf health and survival. The objectives of this study were to estimate genetic parameters for calf passive transfer of immunity through producer-recorded serum total protein (STP) and to determine associations with other routinely evaluated traits in organic Holstein calves (n = 16,725) that were born between July 2013 to June 2018; a restricted subset (n = 7,518) of calves with known Holstein maternal grandsires was analyzed separately. Producers measured STP on farm, and STP was extracted from farm management software. Failure of passive transfer of immunity (FPT) was declared for calves with STP ≤5.2 g/dL. Calves that had the opportunity to reach 1 yr of age were recorded as either staying in the herd or leaving the herd (STAY365). Univariate and threshold models were fitted for STP and FPT, respectively, and included the fixed effects of herd-year-month of birth, calf age in days at STP measurement, dam age in years, and random effects of animal and birthdate within herd. Model effects for STAY365 included the fixed effects of herd-year-month of birth and random effects of animal and birthdate within herd. Multivariate analyses of STP with FPT or STAY365 were conducted to determine the genetic correlation between traits and STP was also regressed on gestation length. Heritability estimates of STP were 0.06 and 0.08 for full and restricted data, respectively. Heritability estimates for FPT were 0.04 and 0.06 for full and restricted data, respectively. The genetic correlation between STP and FPT was near unity. Heritability estimates for STAY365 ranged from 0.08 to 0.11 with genetic correlation estimates between STP and STAY365 ranging from 0.19 and 0.25. Approximate genetic correlations were estimated for sires (n = 302 and n = 256 for full and restricted data, respectively) with at least 10 daughters for STP and predicted transmitting abilities for health, calving traits, and production. Positive approximate genetic correlations were estimated for STP with cow livability, productive life, net merit dollars, and milk yield; favorable approximate genetic correlations were observed for daughter and sire calving ease, and sire stillbirth. Longer gestation length was associated with reduced STP genetically and phenotypically. These results suggest that passive transfer as measured through STP is heritable and favorably correlated with current measures of health, calving, and production.
被动免疫传递对犊牛的健康和生存至关重要。本研究的目的是通过生产者记录的血清总蛋白（STP）估计犊牛被动免疫传递的遗传参数，并确定与在有机荷斯坦牛犊（n=16725）中常规评估的其他性状的关联，这些牛犊出生于 2013 年 7 月至 2018 年 6 月之间；对具有已知荷斯坦母系祖代的小牛的一个受限子集（n=7518）进行了单独分析。生产者在农场测量 STP，并且从农场管理软件中提取 STP。对于 STP≤5.2g/dL 的犊牛，宣布其发生了被动免疫传递失败（FPT）。有机会达到 1 岁的犊牛被记录为留在牛群或离开牛群（STAY365）。针对 STP 和 FPT 分别拟合了单变量和阈值模型，包括牛群-年份-出生月份、STP 测量时的犊牛年龄、母畜年龄和动物及出生日期的随机效应。STAY365 的模型效应包括牛群-年份-出生月份和动物及出生日期的随机效应。对 STP 进行了与 FPT 或 STAY365 的多变量分析，以确定性状之间的遗传相关性，并且 STP 也被回归到妊娠期长度。STP 的遗传力估计值分别为全数据集和受限数据集的 0.06 和 0.08。FPT 的遗传力估计值分别为全数据集和受限数据集的 0.04 和 0.06。STP 和 FPT 之间的遗传相关性接近 1。STAY365 的遗传力估计值在 0.08 到 0.11 之间，STP 和 STAY365 之间的遗传相关性估计值在 0.19 到 0.25 之间。对至少有 10 头女儿的 sire（全数据集和受限数据集分别为 n=302 和 n=256）估计了近似遗传相关性，并且 sire 对健康、产犊性状和生产的预测传递能力。对 STP 与母牛的生存能力、生产寿命、净效益、产奶量等性状之间存在正向近似遗传相关性；对女儿和 sire 的产犊容易度和 sire 的死产存在有利的近似遗传相关性。较长的妊娠期与遗传和表型上的 STP 降低有关。这些结果表明，通过 STP 测量的被动传递是可遗传的，并且与当前的健康、产犊和生产测量结果呈正相关。
