Protein retention in Italian heavy pigs: Development of a factorial approach for the determination of lysine requirement

Abstract

Abstract Protein and lysine retentions were investigated in typical Italian heavy pigs in order to provide a more accurate assessment of amino acid requirements for this type of pig. Results of dissection and chemical composition of 144 pigs, ranging from 80 to 160 kg live weight, from two different genotypes (Duroc X (Large White X Landrace) and Landrace X (Large White X Landrace)) were used. In order to evaluate the practical performance of heavy pigs, data obtained in literature from 523 animals were analysed. A mathematical model (allometric relationship) for calculating daily nitrogen retention in pigs was developed, by using body weight, muscle percentage, and average daily gain as independent variables ( R 2 = 0.95). The requirement for true digestible lysine was assessed by the factorial approach, for different classes of body weight and muscle percentage. The model allows also to calculate total N excretion in heavy pigs, from criteria easily accessible at farm level.