Effects of temperature treatments on the energy and nitrogen metabolism of fed chickens

Abstract

Calorimetric measurements were made for 5 days on individual broiler chickens (1 kg) fed ad libitum and acclimated or unacclimated to 6 temperatures from 2 to 35.degree. C (constant), or alternated between these temperatures and 22.degree. C (alternated). For the 4 treatments, heat production was related to temperatures and the resultant curves were significantly different. Food intake, heat production and maintenance energy requirement all increased linearly with decreasing temperature. Metabolizability of the diet was only 13.8 kJ/g at 35.degree. C, compared with a mean value for all treatments of 14.1 kJ/g. Energy retention and nitrogen (N) retention (g/day, or percent dietary N) were maximal at 22 and 16.degree. C but the amount of energy deposited as protein remained relatively constant below 30.degree. C. Net availability of metaboliable energy [ME] was calculated in 2 ways: by calculating the increase in heat production of fed birds above their starvation values giving a mean value of 0.82 which was similar to the mean regression coefficient which included starvation data; and related ME intake and energy retention. Without these data availabilities ranged from 0.45 at 35.degree. C-1.0 in the cold. Acclimation or alternating of temperature had very few significant effects; there were temperature .times. acclimation effects on N retention and heat production. Similarly alternating temperature significantly increased food intake and heat production at high temperatures, but decreased metaboliability of the diet to 13.7 kJ/g at 35.degree. C from an overall mean of 14.1 kJ/g.