Faculté de médecine vétérinaire, Université de Montréal, 3200 rue Sicotte, St-Hyacinthe, Québec, J2S 2M2, Canada.
Faculté de médecine vétérinaire, Université de Montréal, 3200 rue Sicotte, St-Hyacinthe, Québec, J2S 2M2, Canada.
J Dairy Sci. 2021 Apr;104(4):4914-4922. doi: 10.3168/jds.2020-19476. Epub 2021 Jan 28.
The objective of this study was to identify herd-level colostrum management factors associated with the adequate transfer of passive immunity (TPI; defined as serum Brix refractance ≥8.4% in the first week of life). A total of 59 commercial Holstein dairy farms were included in this observational cross-sectional study. In every participating herd, a minimum of 14 Holstein calves were sampled to measure their TPI using a digital Brix refractometer. Colostrum samples fed to each of these calves were collected to estimate IgG concentration (colostrum quality) using a digital Brix refractometer and bacterial contamination using the Petrifilm (3M, St. Paul, MN) culture system. Dairy producers completed a questionnaire on colostrum management to assess on-farm practices. The study outcome was the prevalence of adequate TPI calculated based on the proportion of adequate TPI (defined with an individual threshold ≥8.4% Brix) on the total samples tested within each herd. According to the threshold determined in a previous study investigating the influencing colostrum management factors to achieve adequate TPI at the calf level, the prevalence of an adequate colostrum volume fed at first meal (≥2.5 L), the prevalence of adequate colostrum quality (≥24.5% Brix), the prevalence of an adequate time to first feeding (delay between birth and the first colostrum meal, ≤3 h), the prevalence of low aerobic bacterial contamination (≤20,000 cfu/mL), the prevalence of low coliform contamination (≤1,000 cfu/mL), and the prevalence of females were calculated. The herd-level prevalence of adequate TPI ranged from 24% to 100%, with a median of 68%. The median herd prevalences of an adequate colostrum volume fed at first meal, of adequate colostrum quality, of an adequate time to first feeding, of low aerobic bacterial contamination, of low coliform contamination, and of females, were 71, 42, 41, 64, 88, and 61%, respectively. In the final model, the prevalence of adequate TPI was associated with the prevalence of an adequate colostrum volume fed at first meal and the prevalence of an adequate time to first feeding. In summary, management practices varied greatly between farms and influenced the prevalence of adequate TPI.
本研究旨在确定与被动免疫充分传递（TPI；定义为出生后第一周血清 Brix 折射度≥8.4%）相关的群体级初乳管理因素。共有 59 个商业荷斯坦奶牛场参与了这项观察性横断面研究。在每个参与的牛群中，至少采集了 14 头荷斯坦小牛的样本，使用数字 Brix 折射仪测量其 TPI。收集了喂给这些小牛的每头小牛的初乳样本，使用数字 Brix 折射仪估计 IgG 浓度（初乳质量），并使用 Petrifilm（3M，明尼苏达州圣保罗）培养系统估计细菌污染。奶牛生产者完成了一份关于初乳管理的问卷，以评估农场实践。研究结果是根据每个牛群中测试的总样本中 TPI 充足（用个体阈值≥8.4% Brix 定义）的比例计算的 TPI 充足的流行率。根据之前研究确定的影响牛群管理因素的阈值，该研究旨在实现小牛水平的 TPI 充足，初乳量充足的流行率（第一餐≥2.5 L），初乳质量充足的流行率（≥24.5% Brix），首次喂食的时间充足的流行率（出生至第一餐初乳的延迟，≤3 小时），低需氧细菌污染的流行率（≤20,000 cfu/mL），低大肠菌群污染的流行率（≤1,000 cfu/mL）和雌性流行率。TPI 充足的群体流行率为 24%至 100%，中位数为 68%。首次喂食时初乳量充足、初乳质量充足、首次喂食时间充足、需氧细菌污染低、大肠菌群污染低和雌性流行率的中位数分别为 71%、42%、41%、64%、88%和 61%。在最终模型中，TPI 充足的流行率与初乳量充足的流行率和首次喂食时间充足的流行率相关。总之，管理实践在农场之间差异很大，影响了 TPI 充足的流行率。
