Calf management and health are essential for setting up the foundation of a productive cow. The objectives of this study were to estimate the impact of preweaning practices on milk production parameters while accounting for an animal’s genetic potential in New Brunswick, Canada. A retrospective cohort study was performed on 220 heifer calves from eight herds born in 2014-2015. Preweaning practices and health data were recorded by producers and reviewed by the herd veterinarian for each calf. The herd veterinarian also visited the farms to collect serum samples from calves and frozen colostrum samples. The production outcomes assessed were milk, protein and fat yields, standardized to 305 d for the first lactation (L1) and a combined group of lactations two and three (L2 + 3). The genomic potential was determined as genomic parent averages (GPA) for the associated production parameters. Analysis was performed with multivariable linear (L1) and linear mixed (L2 + 3) regression models. In L1, for every 1.0 kg increase in weaning weight, milk, protein, and fat yield increased by 25.5 kg, 0.82 kg, and 1.01 kg, respectively (P < 0.006). Colostrum feeding time (CFT) positively impacted L1 milk and protein production, with feeding between 1-2 h of life producing the greatest estimates of 626 kg of milk and 18.2 kg of protein yield (P < 0.007), compared to earlier or later CFT. Fat yield production was decreased by 80.5 kg (P < 0.006) in L1 when evaluating animals that developed a preweaning disease and were not treated with antibiotics compared to healthy untreated animals. Impacts on L2 + 3 were similar across all production outcomes, with a positive interaction effect of CFT and weaning weight. Compared to CFT < 1 h, the later CFT groups of 1-2 h and > 2 h produced greater yield outcomes of 68.2 kg to 72.6 kg for milk (P < 0.006), 2.06 kg to 2.15 kg for protein (P < 0.005), and 1.8 kg to 1.9 kg for fat (P < 0.045) for every one kg increase of weaning weight, respectively. The fit of all models was significantly improved with the inclusion of GPA. These results indicate that colostrum management and preweaning health measures impacted production parameters as adults. The inclusion of GPA significantly improved the accuracy of the models, indicating that this can be an important parameter to include in future studies.

中文翻译：

---

断奶前初乳喂养方法和健康措施对奶牛生产的影响，同时考虑遗传潜力

犊牛管理和健康对于建立高产奶牛的基础至关重要。本研究的目的是估计加拿大新不伦瑞克省断奶前做法对产奶参数的影响，同时考虑动物的遗传潜力。对 2014-2015 年出生的 8 个牛群的 220 头小母牛进行了回顾性队列研究。生产者记录每头犊牛的断奶前做法和健康数据，并由畜群兽医进行审查。畜群兽医还参观了农场，收集犊牛血清样本和冷冻初乳样本。评估的生产结果是牛奶、蛋白质和脂肪产量，第一次哺乳期 (L1) 以及第二次和第三次哺乳期的组合组 (L2 + 3) 标准化为 305 天。基因组潜力被确定为相关生产参数的基因组亲本平均值（GPA）。使用多变量线性 (L1) 和线性混合 (L2 + 3) 回归模型进行分析。在L1中，断奶体重每增加1.0 kg，产奶量、蛋白质产量和脂肪产量分别增加25.5 kg、0.82 kg和1.01 kg（P＜0.006）。初乳喂养时间 (CFT) 对 L1 乳汁和蛋白质产量产生积极影响，与之前或之后相比，出生后 1-2 小时的喂养可产生最大估计的 626 公斤牛奶和 18.2 公斤蛋白质产量（P < 0.007） CFT。当评估患有断奶前疾病且未接受抗生素治疗的动物时，与健康的未治疗动物相比，L1 中的脂肪产量减少了 80.5 kg（P < 0.006）。所有生产结果对 L2 + 3 的影响相似，CFT 和断奶体重具有积极的交互作用。与CFT相比< 1小时，后面的CFT组为1-2小时和＞1小时。2 小时的产量结果更高，牛奶产量为 68.2 千克至 72.6 千克（P < 0.006），蛋白质产量为 2.06 千克至 2.15 千克（P < 0.005），脂肪产量为 1.8 千克至 1.9 千克（P < 0.045）。断奶体重每增加一公斤。纳入 GPA 后，所有模型的拟合度均得到显着改善。这些结果表明，初乳管理和断奶前健康措施影响成年后的生产参数。GPA 的纳入显着提高了模型的准确性，表明这可以成为未来研究中纳入的重要参数。