Energy exchange of two breeds of hens in respiration chambers.

The heat production for two breeds of laying hens was estimated by indirect respiration calorimetry. Using multiple linear regression techniques, egg energy output was identified as a significant contributor to variability in heat production (P = .0113). Heat production of the hens decreased with increasing egg energy output. Body weight, feed intake, egg energy output, and genetic stock were all significant contributors to variability in heat production. Comparisons of traditional techniques (relating energy balance to metabolizable energy intake) and multiple regression techniques (heat production as a function of body weight, feed intake, egg energy output, and genetic stock) for evaluating calorimetry data were made.