Martínez E N, Castillo C, Avendaño-Reyes L, Hernández J, Benedito J L, Rico A, Garcia P, Muiño R
Departament of Animal Pathology, Campus Terra-IBADER, University of Santiago de Compostela, Lugo, Spain.
Institute of Agricultural Sciences, Autonomous University of Baja California, Mexicali, Mexico.
Int J Biometeorol. 2025 Sep;69(9):2325-2336. doi: 10.1007/s00484-025-02969-6. Epub 2025 Jul 22.
Regions with oceanic climates are experiencing unprecedented climatic changes. This study assesses the presence of heat stress in these regions and its impact on reproductive in Holstein cows using the Temperature-Humidity Index (THI), a measure of thermal stress. Data was collected from 159 Holstein cows across experiments. Cows underwent a modified double-ovsynch synchronization protocol, while 96 cows were inseminated based on observed estrous. Cows were examined for body temperature, follicle and uterus examination, and serum progesterone concentrations to evaluate the impact of heat stress. The results of cows pregnancy rate in double-ovsynch synchronized cows were 48.5% and 43.3% in summer and winter seasons, respectively. While the pregnancy rate in non-synchronized cows were 29.5% and 32.7% in summer and winter season, respectively. Elevated THI levels (THI ≥ 72) have adversely effects on reproductive physiology, reduced estrous expression, decreased uterine blood flow, and altered progesterone concentrations. Mild heat stress during summer months in oceanic climate negatively impacted reproductive efficiency in dairy cows, for adaptive management strategies. The double-ovsynch protocol effectively stabilized fertility across seasons, demonstrating its value in improving reproductive outcomes under varying thermal conditions.
海洋性气候地区正经历着前所未有的气候变化。本研究使用温度湿度指数（THI）（一种热应激指标）评估这些地区热应激的存在及其对荷斯坦奶牛繁殖的影响。在各项实验中从159头荷斯坦奶牛收集了数据。奶牛接受了改良的双同期发情同步方案，同时96头奶牛根据观察到的发情情况进行授精。检查奶牛的体温、卵泡和子宫，并检测血清孕酮浓度，以评估热应激的影响。双同期发情同步奶牛在夏季和冬季的妊娠率分别为48.5%和43.3%。而非同步奶牛在夏季和冬季的妊娠率分别为29.5%和32.7%。升高的THI水平（THI≥72）对生殖生理有不利影响，会降低发情表现、减少子宫血流量并改变孕酮浓度。海洋性气候夏季的轻度热应激对奶牛的繁殖效率产生负面影响，需要采取适应性管理策略。双同期发情方案有效稳定了各季节的繁殖力，证明了其在不同热条件下改善繁殖结果的价值。
