Incorporation of lysine from microbial origin into tissue protein of Iberian and Landrace × Large White piglets

Abstract

The distinct incorporation of lysine from microbial origin in tissues has been investigated in Iberian and Landrace × Large White piglets of 47 ± 3 d of age ( n = 8/genotype) given 15N-labelled ammonium sulphate added to the diet. Four piglets of each breed were allocated in metabolic cages to prevent coprophagy. All piglets consumed the labelled diet for 10 days and then were slaughtered. Viscera and carcass weights were recorded and gastrointestinal tissues carefully handled. Samples of carcass, liver, and bacterial pellets isolated from the last third of the small intestine, were hydrolyzed, desalted by ion-exchange, and the amino acids eluted analyzed for 15N-lysine enrichment in a GC-combustion/isotope ratio mass-spectrometer. Background 15N-lysine in tissues was also determined in 3 piglets per breed. Liver enrichment was considerably higher in Landrace × Large White than in Iberian piglets (0.0273 ± 0.0013 vs. 0.0167 ± 0.0013 APE, P < 0.05) that, opposite to our expectations, suggests higher incorporation of microbial lysine in tissues of Landrace × Large White piglets. Protein shortage in the experimental diet relative to requirements could have enhanced microbial lysine absorption in the conventional piglets.