Effect of Environmental Temperature and Dietary Energy on Dwarf and Normal Hens and Normal Roosters

Abstract

This research was designed to provide information regarding the role of environmental temperature and dietary energy in the control of feed intake. Seven-month-old laying hens were individually caged in two environmental chambers for 18 weeks in Experiment 1. A 2 × 2 × 2 factorial design was used with dwarf and normal stock, 22 and 30° C. environmental temperatures, and two dietary energy levels of 250 and 350 kcal. metabolizable energy (M.E.) per 114 gm. (2193 and 3070 M.E. kcal./kg.) of feed. The high energy diet and also the high environmental temperature decreased the feed intake of dwarf and normal hens. Actual energy intake was not affected by different dietary energy levels but high environmental temperature decreased the actual energy intake in normal and dwarf birds. Egg production was adversely affected by high dietary energy levels, but not by high environmental temperature. Body weight change was negatively affected by high environmental temperature. Experiment 2 was conducted with six-month-old roosters to eliminate the variable of egg production. The study was conducted for 12 weeks in a manner similar to Experiment 1 except that three dietary energy levels were used. The results were found to be in close agreement with Experiment 1, except that no significant difference in body weight change was noted either due to environmental temperature or dietary energy. The results of this research indicate that the thermostatic and chemostatic mechanisms for control of feed intake are operative in chickens and that both have a negative relationship to feed intake.