Impact of heat stress on reproductive performance in cattle: a comprehensive review

Heat stress in cattle significantly impacts reproductive performance, physiological health, and overall productivity, particularly during the warmer months. This review examines the multifaceted effects of heat stress on both male and female cattle, focusing on fertility, sperm quality, hormonal imbalances, and behavioral adaptations. Elevated ambient temperatures lead to reduced sperm volume, motility, and viability in bulls, which adversely affects conception rates and subsequent reproductive outcomes. In females, heat stress disrupts estrous cycles, leading to shorter and less intense estrus periods, increased anestrus, and lower fertility rates. Physiologically, heat stress induces hormonal and metabolic changes, such as decreased testosterone levels in males and disrupted progesterone secretion in females, which further compromise reproductive efficiency. Additionally, behavioral responses, such as increased standing time and decreased lying time, indicate an adaptive strategy to enhance heat dissipation, though these behaviors may also contribute to animal discomfort and reduced well-being. Various management strategies, including cooling systems, dietary adjustments, and genetic selection for heat tolerance, are explored as potential mitigative measures. The review underscores the need for continued research and development of effective heat stress management practices to improve cattle welfare and productivity in the face of global warming.