Barley Rations for Swine. II. The Influence of L-Lysine and DL-Methionine Supplementation of Barley-Soybean Meal Diets upon Rate and Efficiency of Gain and upon Nitrogen Retention of Growing Swine
Supplementation of 14% protein barley-soybean meal diets based on an 11.7% protein barley with 0.2, 0.3 or 0.4% of L-lysine or 0.05, 0.1, 0.15 or 0.2% of DL-methionine and fed in meal form failed to affect significantly nitrogen retention (Gm. N/W0.75kg). Diets were fed at the rate of 5.5% of 0.9kg When diets were based on a 13.3% protein barley, fed as meal at the rate of 6.5% of 0.9kg and supplemented with 0.01, 0.2 and 0.3% L-lysine, or 0.05 and 0.1% DL-methionine, or the combinations, highly significant increases in N retention resulted with increasing levels of lysine supplementation. Methionine was without effect and there were no lysine x methionine interactions. Barley rations based on 13.3% protein barley and soybean meal and containing 14% protein were supplemented with 0.15% L-lysine, or 0.1 and 0.2% DL-methionine, or the combination, or with 0.3% of L-lysine, and fed in meal form to 3 individually fed Yorkshire pigs averaging 22.7 kg. Methionine additions did not result in increased rate of gain, and tended to reduce feed conversion efficiency. Lysine additions did not significantly increase rate of gain, but tended to improve feed conversion efficiency. In the final experiment, urea was added to a 13.3% protein barley to increase protein equivalent of the diets to 14%. The diets were supplemented with 0.15 and 0.3% L-lysine, or 0.10 and 0.20% DL-methionine, or the combinations, and were fed in meal form over a 49-day period to 3 individually fed Yorkshire pigs averaging 21.9 kg. Lysine additions significantly increased gains and decreased feed requirement per unit of gain. Methionine additions, alone or in combination with lysine, did not significantly increase gains or improve feed conversion efficiency. Methionine does not appear to be seriously limiting in barley protein, and lysine appeared to be the first limiting amino acid in barley protein for growing swine.