Cutaneous water loss and respiration rates of various breeds of sheep at high ambient temperatures.

The sweating and respiratory rates in rams of Rambouillet (R), Chokla (C), Malpura (M), R x C and R x M breed/breed crosses were recorded when housed in sheds or exposed to 20, 25, 30, 35 and 42 degrees C ambient temperatures in a climatic chamber. The sweating (cutaneous moisture) was higher (P less than 0.05) in Rambouillet and its crosses than the natives, the Malpura sheep producing the least sweat at all temperatures. There was no breed difference in the response of increase in sweating up to 35 degrees C but at 42 degrees C the Chokla showed a considerable increase. Sweating was more pronounced on the shoulder than on the mid-side region. Sweating and respiratory rates increased (P less than 0.05) with the increase in ambient temperature. The Rambouillet exhibited the highest increase in respiration rate at 25 degrees C and the trend continued up to 42 degrees C. The relationship between fleece characteristics, evaporative heat loss tolerance of sheep is dicussed.