Influence of temperature stress on the energy and protein metabolism and requirements of the working horse

Abstract

In coping with the effects of high temperatures, the movement of performance horses from temperate to tropical and sub-tropical regions places major demands on their animals metabolic and cooling systems. Without acclimation, high temperatures increase body core temperature, sweating, metabolic rate, and alter the rate at which glucose and lipids are metabolized. These effects appear to be transitory, as the animal's metabolism returns to near temperate metabolism after 2–3 weeks of acclimatization. High temperatures also result in reduced feed intake. Feeding animals under high temperature conditions generally means keeping forage intake to a minimum and maximizing the energy density of the concentrate. A high fat concentrate is recommended because fat reduces the heat load on the animal, even though the fat may be metabolically less important than glucose. Increased sweat production will increase nitrogen loss, making additional protein intake necessary. Nevertheless, protein intake, above the animal's requirement, may have an adverse effect on body heat production. Therefore, minimizing protein intake, by the addition of appropriate amino acids, such as lysine and threonine, to the diet, may be beneficial.