Ishida Satoka, Nishiura Akiko, Yamazaki Takeshi, Abe Hayato, Nakagawa Satoshi, Nakahori Yuka, Yamaguchi Shigeki, Masuda Yutaka, Saito Yuriko, Tatebayashi Ryoki, Osawa Takefumi, Huang Che-Hsuan, Hagiya Koichi
Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Tsukuba, Japan.
Anim Sci J. 2024 Jan-Dec;95(1):e70013. doi: 10.1111/asj.70013.
Heat stress (HS) reduces dry-matter intake and causes negative energy balance (EB) in Holstein cattle, with consequent deterioration in milk production and wellness. Therefore, the effects of HS can be detected more directly from imbalances in EB than from the consequent changes in production or health traits. EB can be monitored by metabolism-related traits such as predicted EB (PEB), the fat-to-protein ratio (FPR), or β-hydroxybutyrate (BHB) in milk. We examined the days on which HS effects on the test-day PEB, FPR, or milk BHB were the greatest in first lactation. We collected weather records and test-day records. We considered the fixed effects of herd-year, test month, calving age, days in milk, temperature-humidity index (THI) from any one of test day to 14 days prior (15 models per trait), and random effects of animal and residuals in the models and compared the deviance information criterion (DIC) between models for each trait. For PEB, FPR, and milk BHB, the model gave the lowest DIC when including the effect of THI 1, 1, and 0 day before the test day. We observed that HS caused a decrease in PEB and an increase in FPR and milk BHB.
热应激（HS）会降低荷斯坦奶牛的干物质摄入量并导致负能量平衡（EB），从而使产奶量和健康状况恶化。因此，与生产或健康性状的后续变化相比，从EB失衡中能更直接地检测到HS的影响。EB可以通过与代谢相关的性状来监测，如预测的EB（PEB）、乳中的脂肪与蛋白质比率（FPR）或β-羟基丁酸（BHB）。我们研究了首次产犊时HS对测定日PEB、FPR或乳中BHB影响最大的天数。我们收集了天气记录和测定日记录。我们考虑了畜群年份、测定月份、产犊年龄、泌乳天数、从测定日到前14天中任何一天的温湿度指数（THI）（每个性状15个模型）的固定效应，以及模型中动物和残差的随机效应，并比较了每个性状模型之间的偏差信息准则（DIC）。对于PEB、FPR和乳中BHB，当纳入测定日前1天、1天和0天的THI效应时，模型的DIC最低。我们观察到HS导致PEB下降，FPR和乳中BHB升高。
