Nutritional evaluation of wheat 4. Effects of supplementation with amino acids and protein of diets based on wheats containing 10% and 17% crude protein on the performance of growing pigs

Abstract

Summary1. The effects of supplementing diets containing 10% or 17% crude protein wheat, vitamins and minerals with the limiting amino acids were studied with growing Large White x Landrace pigs. Performance was measured in terms of growth rate, feed conversion, carcass measurements, plasma-free amino acid concentrations, digestibility of dry matter, nitrogen and gross energy, nitrogen retention and metabolizable energy.2. With diets based on wheat containing 17% crude protein, a lysine supplement gave a slightly higher growth rate and a slightly lower feed conversion ratio than when fish meal and meat meal was the supplement.3. With diets based on wheat containing 10% crude protein, performance was significantly poorer when the diet was supplemented with the four most limiting amino acids (lysine, threonine, valine, methionine) than with fish meal and meat meal. Meat meal and soya bean meal appeared to be a good source of the limiting amino acids, other than lysine, when added to a diet based on wheat containing 10% crude protein.4. Eye-muscle area was lower and backfat thickness greater when diets based on wheat containing 10% crude protein were unsupplemented or supplemented with lysine than when they were supplemented with protein or with the four most limiting amino acids. However, no significant differences in backfat thickness were obtained between similar comparisons when the wheat contained 17% crude protein.