Genetic and Non-genetic Factors Affecting Heat Production in Farm Animals

Abstract

Farm animals produce heat through a complex biological process that is influenced by their environment, genetics, metabolism, nutrition, and management. Heat stress is a condition that imposes quantifiable consequences on productivity, reproduction, immunological function, and animal welfare across all major livestock species when heat output exceeds dissipation capability. This review examines the biological and environmental factors influencing heat production and heat stress in major farm animal species, including dairy and beef cattle, swine, poultry, water buffalo, sheep, goats, camels, horses, and rabbits. The present review was conducted using secondary sources derived from existing academic literature, including peer-reviewed journal articles, books, and conference proceedings. Each species has distinct vulnerabilities. The fleece that provides sheep with resistance to cold weather also traps metabolic heat in warm weather, a phenomenon known as the "fleece insulation paradox." Although goats have a more flexible thermoregulatory system, prolonged exposure to high humidity can still pose a serious threat to their health. Camels' exceptional heterothermic traits distinguish them from other domestic ruminants. Horses rely primarily on sweat-based cooling at rates that rapidly deplete electrolytes, and they produce exercise-induced heat loads surpassing 1,000 W, an intensity unmatched by other domestic species. With their thin insulating coat, lack of functional sweat glands, and dependence on panting, which becomes ineffective above 28–30°C, rabbits are possibly the most thermally sensitive commonly farmed animal. This review critically evaluates evidence-based mitigation strategies across all ten species, including nutritional interventions, cooling technologies, genetic selection approaches, and real-time monitoring systems, with attention to the diversity of production environments in which these strategies can be applied.