Chapter 2: Thermoregulatory Physiology

[First paragraphs]: Livestock regulate their core body temperature from about 38°C for cattle and swine to about 41.5°C for poultry when exposed to a wide range of ambient temperature extremes. All livestock have various mechanisms to protect their core body temperature from rising when exposed to the summer sun or from falling when exposed to the winter cold. Livestock know when to seek shade during the summer, and to huddle or seek shelter during the winter. Other behaviors help keep the animal in thermal homeostasis, such as orientation to the wind or sun, or tucking in their extremities to conserve heat. If behavior is insufficient to maintain their core body temperature during heat stress, they can utilize autonomic responses such as panting, sweating, or vasodilation of the uninsulated extremities. Likewise, when exposed to cold they can shiver or use non-shivering thermogenesis to generate heat above normal metabolic heat production. Livestock vary in body size, type of insulation, thermoregulatory behavior, how they use evaporative cooling, and how their nervous system integrates thermal information into appropriate autonomic responses.