Thermal Environment Effects on Growing-Finishing Swine Part I—Growth, Feed Intake and Heat Production

ABSTRACT SIXTY crossbred gilts were reared two per pen in five pens each at environmental temperatures of 5, 10, 15, 20, 25 and 30°C. Animals initially weighed an average of 43.6 kg and were slaughtered at an average weight of 86.7 kg. Statistically, growth rate was unaffected by temperature from 5 to 20°C. However, there was a trend toward decreased growth rate from 20 to 5°C and substantial decreases above 20°C. Feed intake decreased as temperature increased from 5 to 30°C and was related to temperature by a polynominal function. Heat production per unit weight decreased with increasing temperature and increased with increasing feed intake and body weight. The heat production data were fitted to a multiple linear regression equation. Conversion of feed to gain was most efficient at 20 and 25°C. The data define a broad range of acceptable thermal conditions rather than a singluar optimal environmental temperature.