Thermoregulation of cattle in tropical environment: an approach with emphasis on physiological responses

Abstract

The effect of thermal environment on the physiological responses of dairy cattle has been extensively studied as a way of characterizing situations of thermal stress caused by tension exerted by the environment to which animals are placed. The thermal requirements of animals vary with the stage of development is that, during the breast-feeding, the calves have a poorly developed thermoregulatory capacity and facilities planning is essential, because they facilitate the management and protecting the animals from adverse weather conditions. Therefore, aimed of this review address the main aspects of thermoregulation in cattle in tropical environment with emphasis on respiratory rate, rectal temperature and body surface. The surface temperature, because it is directly exposed to the environment, varies considerably, which accompany the variations of the meteorological components of the environment in which they live. Since the rectal temperature is a late response to heat stress, with little or no variation. Unlike the rectal temperature, respiratory rate is the first visible sign that shows a heat stress situation. So, to avoid thermal situations that prevent animals to demonstrate all their potential, and avoid damage to the health and reproduction, must provide a microclimate characterized by low temperatures and without exposure to direct sunlight.