Thermal constraints on grazing and browsing herbivores


Finegan EJ, Atkinson JL, Buchanan-Smith JG, Cant JP, Gillespie TJ. 2003. Thermal constraints on grazing and browsing herbivores. In Ward A, Brooks M, Maslanka M, Eds. Proceedings of the Fifth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Minneapolis, MN.


There are five ways in which an animal may exchange heat with its environment: solar (shortwave) radiation gain, longwave radiation exchange, convective exchange, conductive exchange, and heat loss by evaporation. This heat exchange, in combination with the metabolic heat produced by the animal, defines the animal’s heat balance (Figure 1). When a homeothermic animal cannot lose sufficient body heat (generated by metabolism, or gained from the environment) to maintain a stable body temperature, the animal experiences heat stress. In a cold environment when the same animal loses heat to the environment faster than metabolic heat is generated, or heat is gained from the environment, the animal experiences cold stress. Under conditions of heat stress, animals may seek a cooler environment in the shade, while under conditions of cold stress animals find relief by sheltering from wind, rain, and snow.     46 KB