Comprehensive review of heat stress effects on dairy cattle: the implications for production, reproduction, and adaptation in the context of climate change

Heat stress poses a significant threat to dairy cattle, impacting their physiological, reproductive, and production performance. This review aims to provide an in-depth examination of the effects of heat stress on dairy cattle, fo- cusing on how elevated ambient temperatures influence milk production, reproductive efficiency, and overall animal health. The physiological responses to heat stress, including increased respiration rate, elevated body temperature, and changes in feeding and drinking behaviors were analysed and discussed. Heat stress leads to a decrease in feed intake, an increase in water consumption, reduced growth rates, and diminished milk yield and quality. Reproductive performance is also adversely affected, with reduced fertility and increased risk of embryonic loss. Dairy breeds, particularly those with higher production levels, are more susceptible to heat stress due to their higher metabolic heat production. The review highlights the impact of heat stress on the immune and endocrine systems, increasing vul- nerability to diseases and inflammatory conditions. Given the limited capacity of animals to adapt to the rapid pace of climate change, the review underscores the need for effective management strategies, including environmental modifications and genetic selection, to mitigate the adverse effects of heat stress. Finally, sustainable dairy farming remains a significant challenge in the context of global climate change and rising temperatures.