142 Programming effects of early-life exposure to heat stress in cattle

Abstract As the Earth’s temperature continues to increase, the livestock industry faces a growing challenge related to heat stress. Heat stress significantly impacts the global dairy and beef industries, affecting milk and meat production, reproductive health, and the general welfare of animals. This presentation will showcase how early-life exposure to heat stress in cattle, specifically during the prenatal (in utero) and postnatal (pre-weaning) phases of the life of a calf, can program them for a lifetime. Our studies have aimed to understand the physiological and behavioral changes that early-life heat stress induces and the molecular mechanisms underlying long-term programming effects on growth, survival, and lifetime performance. Using a multifaceted approach, we have investigated the transcriptomic, epigenetic, and metabolic responses of calves exposed to heat stress or provided with heat abatement during critical developmental periods. Our studies shed light on how early-life exposure to heat stress alters the developmental trajectory of cattle, potentially influencing their resilience to future environmental challenges and overall productivity. Strategies for mitigating heat stress in beef cow-calf pairs and pregnant dairy cows (e.g., pasture artificial shade and evaporative cooling, respectively) will be discussed. These research insights will aid in developing targeted management strategies and breeding programs to reduce the adverse programming effects of heat stress in cattle, ensuring the sustainability and resilience of livestock production systems in the face of climate change.