Feed and water consumption patterns of broilers at high environmental temperatures.

Broilers were reared on litter to determine the effect of cyclic environmental temperatures on feed and water consumption patterns. The temperatures were constant at 24 C for several days before cyclic temperatures were started. Control broilers continued at 24 C but the treatment was a daily 24-35-24 C cycle for 3 days. Broilers that were 5, 6, or 7 wk old consumed as much feed or water the 1st day of the cycle as on the succeeding days. Feed and water consumption were determined for 6-h periods each day beginning at minimum temperature with two periods during rising temperature and two periods during declining temperature. Feed consumption was depressed when the temperatures were declining. Water consumption increased during the 12 h when the temperature was maximum. At 7 wk, water consumption was greater for broilers on the cyclic temperature for each 6-h period except for the period of temperature decline immediately preceding the minimum temperature. Broilers exposed to the 3 days of cyclic temperatures consumed more water than controls during a subsequent exposure to temperatures up to 40.8 C. The data show that the increased water consumption and decreased feed consumption observed due to high, cyclic temperatures arise from changes that occur during some times of the day and no changes occur during other times. The increase in water consumption precedes the reduction in feed consumption.