Effects of environmental temperature and heat production due to food intake on abdominal temperature, shank skin temperature and respiration rate of broilers.

1. Eight broilers were used to determine the effects of environmental temperature and the increased heat production attributable to food intake on thermoregulatory physiological responses. Heat production, abdominal temperature, shank skin temperature and respiration rate were measured. 2. Heat production rose with increase in food intake and environmental temperature. Abdominal temperature, shank skin temperature and respiration rate also increased but, at 36 degrees C, there was no difference in respiration rate between the different rates of food intake after exposure for 1 h. Also, heat production decreased with exposure time when the birds were exposed to 28 degrees C and 32 degrees C, but increased at 36 degrees C ambient temperature. 3. Although the effect of the increased heat production on thermoregulatory physiological responses was not greater than that of environmental temperature, the increase in heat production enhanced the effect of ambient temperature on thermoregulatory physiological responses. However, with increasing heat production, the greatest response in shank skin temperature was at 28 degrees C, in respiration rate at 32 degrees C and in abdominal temperature at 36 degrees C. 4. These results suggest that, at high environmental temperatures, arranging feeding management to restrict the increase in heat production may alleviate the effect of environmental temperature.