Feeding pattern responses to changes in dietary energy or environmental temperature in the domestic fowl

Two experiments using 64-week-old Single Comb White Leghorn roosters were conducted to determine the meal response to an abrupt change in dietary energy or environmental temperature. In the first experiment, dietary energy level was changed from 200 kcal to either 250 or 150 kcal/75 g. In the second experiment, environmental temperature was changed from 22.2 C to either 13.3 or 30.0 C. Feeding behavior was recorded throughout both experiments. Meal size, meal frequency, and time spent eating a meal were measured. Roosters changed to high-energy or low-energy diets consumed low or high amounts of feed, respectively. Those fed the high-energy diet tended to decrease meal size and meal duration and to increase the number of meals. Roosters changed to the low-energy diet decreased meal size and meal duration and increased the number of meals eaten. The results tend to confirm the chemostatic mechanism in birds as food intake was related to energy in the diet. Roosters changed to high or low environmental temperature responded by decreasing or increasing their feed intake, respectively. Roosters changed to a high environmental temperature significantly decreased meal size, meal duration, and increased the number of meals. Those changed to a low environmental temperature significantly increased meal size and decreased meal frequency and meal duration.