The Effects of Ambient Temperature and Air Movement on Localized Sensible Heat-Loss from the Pig

Abstract

SUMMARY Three pairs of pigs, aged 1-2 weeks, 10-12 weeks and 20-23 weeks, were exposed to windspeeds approximating to 8, 35, 60 and 100 cm./sec. at ambient temperatures from 15-35°C. and 8 cm./sec. (near to still air conditions) at lower temperatures. Heat loss rate was measured at one place on the animal’s back using the Hatfield heat flow disc. Skin (ear and back) temperatures and deep body temperatures were recorded. The increase in the rate of sensible heat loss due to raised windspeed was higher at the lower temperatures. The effects of increased windspeed could be equated to equivalent still air temperatures in respect of heat loss from the back, but not in respect of changes in skin temperatures on both the ear and the hack. The ear temperature was less affected by wind than by ambient temperature so that the total sensible heat loss due to wind would be greater than that due to the equivalent still air temperature in which the ear temperature was lower.