Theoretical aspects of a flexible model to stimulate protein and lipid growth in pigs

Abstract

Summary A model designed to simulate growth in pigs has been developed to include the following aspects of protein and energy use. 1. It is proposed that the ratio of protein accretion to protein synthesis is a function of protein mass. Synthesis rate influences the efficiency of protein use, the energy cost of protein accretion and the energy cost of maintenance. A calculated energy cost for protein synthesis of 7·3 MJ ME/kg is suggested; the calculated energy yield from deaminated protein is 11·5 MJ ME/kg. 2. Urinary losses of nitrogen are derived from estimates of protein quality by essential amino acid index, endogenous losses and the rate of protein accretion. 3. A minimum fat to protein ratio in the gain of growing pigs of 1: 1 is assumed. 4. An estimate of critical temperature which is dependent upon live weight and heat output is used to calculate energy expenditure for cold thermogenesis.