Nutritive value of oat and rye grain protein as influenced by nitrogen and amino acid composition

Abstract In experiments with increasing applications of nitrogen to oats and rye grown in pots, grain with widely varying N‐content was obtained. In rye increasing N‐concentrations were associated with decreases in the protein of lysine and several other amino acids including threonine, tryptophan, methionine and cystine, whereas glutamic acid, proline and phenylalanine increased. In oat protein the amino acid composition was less affected by increasing N‐content in grain. Concentrations of most essential amino acids were higher in oat than in rye protein, especially at high N‐levels. The ratio lysine + arginine/proline was higher in oat than in rye protein and did not, as in rye, decrease with increasing N‐concentration. Lysine as a percentage of dry matter increased up to the highest N‐level in both cereals. In rat feeding experiments true digestibility of the protein of oats and rye increased to the same extent with increasing N‐concentration in grain, whereas the biological value of the protein decreased considerably in rye but only slightly in oats. Net protein utilisation decreased with increasing N‐content in rye but increased in oats.