Department of Grassland and Natural Landscape Sciences, Poznań University of Life Sciences, 60-632, Poznan, Poland.
Department of Animal Physiology, Biochemistry, and Biostructure, Poznań University of Life Science, 60-637, Poznan, Poland.
Sci Rep. 2024 Sep 11;14(1):21211. doi: 10.1038/s41598-024-72294-2.
This study aimed to investigate whether heat stress, as defined by the temperature-humidity index (THI) during the close-up dry period, had any impact on the productive performance, fertility, and immunometabolic blood indices of dairy cows in the subsequent lactation. Lactation performance was associated with increasing THI values on - 21, - 14, and - 7 d before calving resulting in decreased milk yield by about 2.30, 2.60, and 2.90 kg, respectively. The THI on the - 7 d before the calving was negatively associated with fertility parameters such as delayed first estrus postpartum, an elongated calving interval by approximately 32 d, a higher number of services per conception by 1.00, and an elongated artificial insemination service period, days open, and inter-calving period by about 20, 52, and 52 d, respectively. The study found that the immunometabolic blood indices were associated with increasing THI values during the close-up dry period. The study showed that exposing dairy cows to close-up dry period heat stress had negative consequences on performance, fertility, and immunometabolic blood indices in the subsequent lactation. Therefore, it is recommended that herd management and barn microclimate changes be implemented earlier, starting from the late dry period, to mitigate the negative impact of heat stress.
本研究旨在探讨在奶牛干奶期接近尾声时，以温湿度指数（THI）定义的热应激是否会对奶牛随后泌乳期的生产性能、繁殖性能和免疫代谢血液指标产生影响。泌乳性能与分娩前-21、-14 和-7 天的 THI 值呈正相关，导致产奶量分别减少约 2.30、2.60 和 2.90 公斤。分娩前-7 天的 THI 与繁殖性能参数呈负相关，如产后首次发情延迟、产犊间隔延长约 32 天、每配种服务次数增加 1.00 次、人工授精服务期、空怀期和产犊间隔分别延长约 20、52 和 52 天。研究发现，免疫代谢血液指标与干奶期接近尾声时 THI 值的增加有关。该研究表明，让奶牛在干奶期接近尾声时暴露于热应激下，会对随后泌乳期的生产性能、繁殖性能和免疫代谢血液指标产生负面影响。因此，建议从干奶后期开始，更早地实施畜群管理和畜舍小气候改变，以减轻热应激的负面影响。
