Familial Differences of Single Comb White Leghorn Chickens in Tolerance to High Ambient Temperature

Abstract

EVIDENCE has been reported by several workers that heat tolerance in chickens is genetically controlled. Hutt (1938) observed that mortality during three successive hot days was affected by age and breed, and that White Leghorns had less mortality than Barred Plymouth Rocks and Rhode Island Reds. Yeates et al. (1941) found that White Leghorns showed less change in body temperature than did Australorps when subjected to increased temperatures. In a study of the response of six different breeds to 105°F. (40.56°C.) and 25% relative humidity (RH), Lee et al. (1945) found that White Leghorns had the least rise of body temperature. However, when the RH was increased to 75%, Brown Leghorns showed the least reaction, White Leghorns were intermediate and Australorps and Rhode Island Reds showed the most reactions. Hillerman and Wilson (1955) tested the reaction of hens to sudden changes in temperature and compared this to their adapted performance… .