Observations on the effect of environmental temperature and environment at moult on the heat production and energy requirements of hens and cockerels of a White Leghorn strain

Abstract

SUMMARY The heat production of hens and cockerels of a White Leghorn strain (‘H & N’) was measured after acclimation to environmental temperatures of 16, 23, 27 and 33 °C. No difference in fasting heat production was found between 16 and 23 °C for well-feathered hens in the first few months after moult though there were substantial reductions at 27 °C and above. Both hens and cockerels showed a trend of increasing net availability of metabolizable energy with increasing environmental temperature though this was non-significant. There were significant reductions between 16 and 27 °C in the metabolizable energy requirements for maintenance for both sexes. Results are also given for the heat production of laying hens exposed to short daylight periods and high or low environmental temperatures. Although the mean fasting heat production of the high-temperature group was greater, the difference was not statistically significant.