The Energy Requirements and Performance of Growing Chickens and Turkeys as Affected by Environmental Temperature

The energy requirements for growth and maintenance were studied in male and female chicks and turkeys, kept in environmental chambers for 4 to 5 weeks following the brooding period. In both species and sexes, the maintenance requirement decreased with constant temperatures from 12 to 24 C, reaching a low between 24 and 28 C, followed by an increase as the temperature was raised further. At 12 C, the maintenance ranged between 2.45 and 2.70 kcal/g2/3, for chicks and turkeys, respectively. Requirements for weight gain averaged 1.87 kcal/g and .7 kcal/g in chicks and turkeys, respectively. This species difference was explained on the basis of carcass composition. Turkeys fed a high-protein diet had an apparently greater maintenance requirement than those fed a diet appropriate for their age. Weight gain decreased between 19 and 34 C in chicks and between 18 C and 32 C in turkeys. Feeding of a high protein diet tended to reduce but did not overcome the growth depression by temperature. In turkeys, weight gain at 12 C was inferior to that at 18 C for both sexes. The calculated amino acid per kilocalorie dietary requirements for 6-week-old chicks increased with temperature to a peak at 27 C, followed by a decrease as the temperature was raised further.