Further studies on the energy and protein metabolism of pigs growing at a high ambient temperature, including measurements with fasting pigs

Abstract

SUMMARY1. The experiment was designed to compare the protein and energy metabolism of pigs growing at 25°c or 34°C. The pigs were given two levels of feeding while growing between 25 and 75 kg live weight.2. The high temperature was associated with increases in rectal temperature of 1·2 to 20°C. Both pigs on the higher level of feeding at 34°C became lame in their hind legs.3. The high temperature was also associated with increases in heat production and in urinary nitrogen and energy losses for pigs fed at the higher level of feeding only; however fasting heat production was not affected significantly by temperature. The high temperature had no effect on the apparent digestibility of the diet.4. It was calculated from data for pigs at both levels of feeding kept at 25°C, that efficiency of utilization of metabolizable energy (ME) above maintenance was 71%, and the maintenance requirement for ME was 100 kcal/kg0·75 day. Energy retention was reduced at 34°C in pigs fed on the higher level of feeding.