Abstract
There are many camel breeds existing in Saudi Arabia, where coat colour represents the main criteria to name the breed. Breeds colour has been indicated as an important influential factor for body temperature and heat tolerance in various farm animals. The present study was aimed to investigate the variation in thermophysiological responses and heat tolerance of four Saudi camel breeds. Sixteen dromedary bulls of native breeds (Almajaheem, Almaghatir, Alsafrah, Alzargeh) of 4 animals each with mean body weight of 250 +/- 10 kg and 18 months of age were used in this study. Exposure of camel breeds to the hot summer (40 degrees C) compared to spring (21 degrees C) natural environmental conditions resulted in variable breed-dependent thermophysiological responses. The observed percentage increase in rectal temperature (Tr.) and respiratory rate (RR) due to summer heat exposure were highest in Almaghatir and Alsafrah breeds, respectively and lowest in Alzargeh breed. On the other hand, the percentage increase in packed cell volume (PCV) was highest in Almajaheem and Alzargeh breeds and lowest in Alsafrah and Almaghatir breeds. Further, all breeds have showed heat tolerance coefficient of 90% or more, where Alzargeh proved to be the best heat tolerant camel breed followed by Almajaheem, then Alsafrah and finally Almaghatir. The obtained results indicate that coat colour do not influence heat tolerance in camels. Nevertheless, further studies are needed to explore the role of breed variation in the structure of insulating coat and optical properties of coat hair on thermoregulation and heat tolerance of camels.