The influence of loss of plumage on temperature regulation in laying hens

Abstract

Summary: The acute thermoregulatory responses of normally feathered (control) and poorly feathered laying hens were studied in the ambient temperature range from 0 to 38 °C.Core body temperature in the poorly feathered birds began to fall at between 15 and 20 °C but this difference from the controls was significant only at 0 and 5 °C, when there was severe hypothermia. The temperature on the skin of the back was significantly lower at 20 °C and below, but the comb temperatures did not differ.The rate of oxygen consumption in the poorly feathered hens was significantly higher than that of the controls at 30 CC and below; at the acclimation temperature (20–25 °C) the difference was about 62%. The rate of increase of heat production with falling ambient temperature was 2–6 W/ma/°C in the poorly feathered group and 1–0 W/ma/°C in the controls.Absolute rates of evaporative heat loss did not differ between the two groups.The ratio of the coefficients of dry heat transfer in the poorly feathered and control birds at 0–30 °C was 2–1:1.