Since mammals and avian that form bulk of farm animals are homeotherms and hence maintain a constant body temperature, they possess means for producing and losing heat during extreme cold or heat conditions respectively.
Hear Production: Animal produce heat when transforming chemical energy of food into work. Under normal circumstances a grazing animal while in the sun may gain heat directly or indirectly from solar radiation. The added solar heat and metabolic heat generated from food and muscular activities form the animal heat gain.
The heat gains in one animal vary from another as a result of:
(a) the intensity of heat production by different organs varies depending of the weight of the organ. On net weight basis, the brain generates heat faster than the muscular tissue due to higher density of the former
(b) the body size also affects heat requirement, for instance, smaller sized animals require a greater heat production per unit weight than larger sized animals if the same temperature is to be maintained. This is because the smaller the animal, the greater the surface area and the more the heat loss
(c) specific surface area which is the ratio of surface to volume determines heat loss. This is because with increasing body size, the surface to volume of the animal increases, and therefore the relative surface from which is dissipated increased. When heat production is better expressed per unit surface area, the effect of body size is largely eliminated. Heat production is better expressed in terms of body surface area.
Evaporation: Evaporative water loss occurs from the skin after it has been secreted by the sweat glands. Other areas of evaporative of water losses include respirative water loss and sweating. The two forms of water are two major processes used in temperature regulation in animals. The process of evaporation of water requires a large amount of energy and is therefore used to cool the body of animal. Evaporation occurs only when the air is not saturated already with water.
Metabolic and Chemical Heat Transfer
With increasing environmental temperature body temperature for homeotherm is constant while that for poikilotherm increases. Increasing ambient temperature for poikilotherms increases the metabolic rate and decreases with decreasing ambient temperature similar normal chemical
reaction.
However, with homeotherms, the metabolic rate decreases with increasing temperature and increases with decreasing temperature. Other chemical reactions like muscular activities, shivering and metabolic reaction of the liver are also involved e.g. liver apart from producing
heat also releases glucose into circulation which is a basic requirement for chemical temperature regulation.
Read Also: Adaptive Means of Coping with the Environment in Animal Production
