Prediction of production : nutrition induced tissue partitioning in growing pigs

In several swine growth models, a constant ratio is assumed between lipid deposition rate and protein deposition rate when pigs are fed below their protein deposition capacity. In the present thesis, it was studied whether there is an effect of energy intake, live weight and nutritional history on composition of growth in restrictedly fed pigs. Results showed that all three mentioned factors affected the composition of growth. Fatness of deposited tissue increased both with an increase in energy intake and with live weight. It was concluded that the composition of total tissue is not constant. It was derived that the composition of extra tissue, deposited due to extra energy intake is independent of energy intake. This extra tissue is consistently fatter than total deposited tissue. This explains the increase in fatness of pigs with each increase in energy intake. It was studied which factor (energy intake or body weight) is of major importance for the partitioning of tissue. Composition of growth was affected by energy intake to a considerably larger extent than by live weight. Furthermore, data on the partitioning of deposited protein and lipid within the body showed that, even at low energy intakes, the major part of extra tissue (due to extra energy intake) was deposited in non-lean carcass parts.