The nitrogen metabolism of the young pig. II—Effect of heat treatment on the ‘available’ lysine content fish meal and the performance of pigs

Young male pigs were given diets containing barley and fish meal with added minerals and vitamins. The fish meal was Peruvian or white fish meal of similar ‘available’ lysine content but different total lysine content, heated white fish meal with the same total but reduced ‘available’ lysine content, or heated white fish meal with supplementary lysine. There was a reduction in the nitrogen retention, growth rate and feed conversion of the pigs when the heated meal was given, but there were no significant differences in these criteria for pigs given the Peruvian or the white fish meal. Some of the reduced performance on the heated meal was due to a lowering of the digestibility of dry matter and the addition of synthetic lysine to the diet containing heated fish meal only partly restored nitrogen retention, growth rate and feed conversion.