Role of coat colour in body heat regulation among goats and hairy sheep in tropics

Abstract

This experiment was conducted during the hottest and the leanest period of the year in the tropical semi-arid northeast of Brazil to evaluate the relative response of black and white varieties (with the colour of skin and of hair being the same) of goats and hairy sheep to grazing under direct solar radiation. There was a marked increase in midside-skin (MS), ear-skin (ES) and rectal temperatures (RT) and respiratory rate (RR) at 2 P.M. The afternoon increase was more in sheep in MS, RT and RR, but ES increased more in goats. Black animals had uniformly higher MS. White sheep had higher ES but in goats colour had no effect. Right ES was higher in sheep and there was some tendency of higher right ES in general. The black goats respired at much higher rates than the white, but in sheep, colour did not influence RR. Colour of animals did not influence RT. There was significant day-to-day variation, possibly associated with small fluctuations in environmental temperature, in MS, ES and RR but not in RT. The results indicate that goats appear to be better adapted than hairy sheep and white goats better than black goats under local climatic conditions.