Impact of Temperature-Humidity Index (THI) on Disease Susceptibility in Dairy Cattle in India: Mechanisms, Evidence, and Mitigation Strategies.

India’s tropical and monsoonal climate subjects’ dairy cattle to significant Temperature-Humidity Index (THI) fluctuations, often exceeding thermal comfort thresholds and resulting in heat stress. Regional patterns highlight chronic humidity-induced stress in Kerala and Coastal Andhra Pradesh, heatwave-driven reproductive and respiratory disorders in Tamil Nadu and Karnataka, and severe pre-monsoon heat with subsequent vector-borne disease outbreaks in the Northern Plains. These stressors collectively lead to substantial reductions in milk yield (up to 30%), compromised milk quality, reproductive inefficiencies, and heightened disease susceptibility, causing national-level economic losses estimated at over INR 2,600 crore annually. Projections under future climate scenarios indicate even greater losses, particularly in the Northern Plains. Addressing this requires integrated mitigation strategies, including immediate cooling interventions, strategic breed selection, improved management practices, and policy-backed financial planning to enhance resilience and sustain India’s dairy sector in a changing climate.