EFFECT OF BODY-COMPOSITION, FEED-INTAKE, AND AMBIENT-TEMPERATURE ON HEAT-PRODUCTION OF VIETNAMESE SWAY-BACK PIGS

From theoretical considerations animals with a higher protein-fat rati o in the body should have a higher maintenance energy requirement (MEm ). The literature on this problem shows a non-uniform picture with dev iating results. From the results of a series of experiments it is poss ible to compare the heat production (HP) of male and female animals of the Vietnamese Sway-back breed pigs which vary quite widely in their body composition. The protein-fat ratio was 1.2 for the male and 0.2 f or the female animals. In the experiments 4 male and 4 female animals in the live weight range of 20-33 kg and 33-42 kg, respectively, were involved. The HP measurements were carried out in climatized respirati on chambers on two levels of energy intake at ambient temperatures of 6 degrees C, 12 degrees C, 18 degrees C, 24 degrees C, 30 degrees C, a nd 35 degrees C. The dependence of HP on the ambient temperature has b een described by a cubic regression function. Thermoneutral temperatur es are lower in the female animals caused by the better insulation eff ect of the backfat. The difference in HP which was expected by the lar ge difference in body composition, was not found. The absolute protein mass determined the correlation to HP. Certainly the difference incre ased after lowering the ambient temperature. The influence of differen t factors on HP is discussed.