Kara, HalimeGueven, Mustafa2025-03-202025-03-2020241300-08611308-2817https://doi.org/10.33988/auvfd.1346189https://hdl.handle.net/20.500.14034/2227The effects of heat stress on colostrum quality, passive transfer failure, and disease incidence were investigated in a large population in order to prevent calf morality and yield losses in Holstein cows and calves. There was a statistically significant correlation between colostrum quality and the daily temperature humidity index, 7-day average temperature stress, and average temperature humidity indexes experienced by the cows during the dry period (P<0.001). It was observed that passive transfer failure occurred in 21% of the calves. There was a significant positive correlation (P<0.05) between the relative humidity and the temperature and humidity index values of the day of birth and the calf serum brix value. A negative and significant correlation was observed between Temperature-Humidity Index (THI) and serum brix value (r =-10, P<0.01). It was observed that the passive transfer success and diarrhea and pneumonia that were overcome in the first 365-day period showed a negative correlation (P<0.01). As a result, it has been observed that the heat stress experienced by cows and calves affects colostrum quality and passive transfer success, which also affects development and protection from diseases.eninfo:eu-repo/semantics/openAccessColostrum QualityHeat stressPassive transfer failurePassive transfer immunityTemperature humidity indexArticle10.33988/auvfd.1346189714481486Q3WOS:0013349497000022-s2.0-85209195898Q3