Physiological changes associated with acclimation of broiler chickens to constant temperatures

An experiment was conducted to determine whether the physiological parameters that respond to temperature would equate to a common level after birds are acclimated to differing temperatures and then reared as one group at a common temperature. Results show that of the parameters measured, the heart/body weight ratio is the most sensitive to temperature changes. When birds were reared in differing constant temperatures from 1 to 28 days of age and then subjected to a common environment, by 56 days of age, the heart/body weight ratio had equated. However, the liver- and adrenal/body weight ratio and hematocrit did not completely equate for the temperature extremes by 56 days of age. Parameters measured but unaffected by temperature treatment were spleen- and bursa/body weight ratios.