The nitrogen metabolism of the young pig. I.—supplemental value of certain amino–acids when added to groundnut meal rations

Young pigs weighing between 25 and 50 lb. live‐weight were fed diets consisting of cereals and groundnut meal alone, or with additions of L ‐lysine monohydrochloride, or DL ‐methionine, or both. Nitrogen retention was measured over 5‐day‐periods, and a highly significant increase was obtained with the L ‐lysine supplement at all levels of crude protein. Groundnut + lysine diets were as good as white fish meal diets, providing similar total lysine levels when the protein level was 12 or 15%, but were inferior at 18 and 21% crude protein. No significant response was obtained to DL ‐methionine except at 18% crude protein, when it depressed nitrogen retention. The greatest nitrogen retentions were obtained either at 18% or 21% of dietary crude protein.