Estimates of heat exchange in native breeds of sheep kept in a controlled environment

Abstract

The aim of this research was to determine the levels of heat stress and sensible and latent heat loss in sheep of the Soinga, Morada Nova and Santa Inês breeds, kept in a controlled environment at thermoneutral temperatures (TN: 20.0, 24.0 and 28.0°C) and under heat stress (TS: 32.0 and 36.0°C). Eighteen non-castrated male sheep of the Soinga, Morada Nova and Santa Inês breeds were used, with an average age of 5±1.0 months and an average weight of 15±2.3kg. The behavior of the physiological variables as a function of temperature was significant (P.0001), and there was an increase in the values of the physiological variables as the temperature rose. Sensible heat loss showed an inverse correlation with the physiological variables, RT, RR and ST of -0.31; -0.65 and -0.46, respectively. The two principal components together explain 84 % of the variation in the data, but with just one PC, there is 70 % of the variation in the data. In thermal conditions of 36°C, the animals lost almost all, plus 90 per cent, of the surplus metabolic heat in latent form (skin and respiratory tract). As AT rose, RR and ST responses showed higher correlations with total latent and sensible exchange, respectively.