RELATIONSHIP OF WEIGHTS OF CHEMICAL COMPONENTS AND EMPTY BODY WEIGHT IN YOUNG PIGS

Abstract

The influence of genotype, sex, frequency of feeding, and plane of nutrition on the relationship between weights of chemically determined components in the empty bodies and the empty body weight was estimated by the use of simple linear regression analyses. The data used were body composition from three experiments involving 107 pigs belonging to Lacombe, Yorkshire, Lacombe × Yorkshire, and Hampshire × Yorkshire breeds representing both sexes and fed at levels of dietary energy inputs varying from 120 to 340 kcal ME/W0.75kg daily. All experiments consisted of a feeding trial and a comparative slaughter analysis. Within a range of 5-35 kg of empty body weight (EBW) the rate of increase in the water, protein, fat, and ash components in the empty body was a linear function of the increase in EBW. The rate of increase in weights of chemical components as a percentage of increase in EBW was: water 60.9; protein 16.3; fat 20.2; and ash 2.7. These estimates were similar for pigs of different breeds and whether fed two or five times daily. The rate of accretion of water per unit increase in EBW was greater in male than in female pigs. Plane of nutrition ranging from 220 to 340 kcal ME/W0.75kg daily did not affect the rate of deposition of water, protein, fat, or ash components per unit increase in EBW. Pigs fed at the maintenance level of feeding (120–140 kcal ME/W0.75kg daily) had a greater rate (P < 0.05) of accretion of water per unit increase in EBW as compared with pigs fed 320–340 kcal ME/W0.75kg per day. The rate of accretion of ash per unit increase in EBW in pigs fed 120–140 kcal ME/W0.75kg per day was greater (P < 0.05) than for pigs fed 220–240 kcal ME/W0.75kg per day. The rate of change in the protein and fat components remained constant. The results are discussed in relation to the concept of mass-related homeostasis.