Heat Tolerance of Local Goat Breeds in Saudi Arabia PDF

Keywords

Heat tolerance, thermal stress, solar radiation, thermoregulation, Aardi, Hipsi and Zumri goats

Abstract

In order to evaluate the heat tolerance of three local goat breeds of Saudi Arabia, Hipsi, Aardi and Zumri, four bucks from each breed were exposed to direct sun with or without access to water during hot summer. Exposure of goats to direct sun for five hours for five consecutive days (three days with water and the last two days without water) resulted in a significant(P<0.01) increase in rectal temperature in all goats; however, it was further increased when the goats were not allowed to drink. Aardi goats had a higher rectal temperature during both pre and post-exposure when they were not watered during exposure to direct sun. Respiration rate was also increased (P<0.01) in response to exposure to solar radiation in all breeds but with varying degrees; it was increased by 133%, 205% and 290% in Hipsi, Aardi and Zumri goats, respectively. Also, there was a trend of increase in respiration activity, when water was withheld during exposure time. Sweating rate was slightly increased following exposure to direct sun. Aardi goats showed an increase in cutaneous water loss during water restriction over that recorded when they had free access to water, while it remained unchanged in the other two breeds. Hipsi goats displayed lower sweating rates in comparison to Aardi and Zumri goats. Feed consumed per kg body weight during the time of exposure to direct sun was the highest in Aardi goats, and also their feed intake was less depressed by withholding of water in comparison to the other. Furthermore, feed intake per kg body weight while the goats were kept indoors (other than the item of exposure to direct sun) as well as the daily feed intake was the highest in Aardi goats. It was concluded that there were no differences between breeds in heat tolerance when the water supply was maintained ad libitum. However, when water was withheld, Aardi goats enhanced their evaporated heat loss and maintained higher levels of feed intake despite their relatively higher rectal temperature.