Temperature-Humidity Index Values and Their Significance on the Daily Production of Dairy Cattle in the North African Arid Region

Climate changes affect the economic viability of livestock. Therefore, this study aimed to characterize heat stress in Holstein cattle raised arid region Tunisia as well evaluate effect temperature-humidity index (THI) on daily milk production and components. For reason, 76940 monthly individual records collected from 1995 2018 3056 cows were used. THI calculated ambient temperature relative humidity was used a measure stress. To production, repeated measures linear mixed model Results showed significant (P<0.01) decrease yield, protein, fat content all cow’s parity classes. each point increase values beyond 64, fat, protein contains decreased by 0.32 kg, 0.09, 0.06 %, respectively. Moreover, when value varied 64 85, 29 17 30 %. Heat impact negatively components dairy cows. These results can be way improve length productive life for hard climate. Serious management strategies are needed cow productivity minimize impact.