Effects of combining protein sources on lysine utilization by starter pigs.

The effect of combining protein sources on lysine utilization was evaluated using 450 crossbred starter pigs, average initial weight 6.8 kg and final weight 17.4 kg, in four replicates of 12 dietary treatments. Pigs were fed ad libitum a corn-soybean meal basal diet containing .65% total lysine, supplemented with one of four lysine sources: L-lysine X HCl, soybean meal, meat and bone meal and a combination of meat and bone meal and soybean meal with each providing equal lysine. The levels of supplemental lysine added to the basal diet by addition of the lysine sources were: 0, .15 and .30% L-lysine X HCl and .10, .20 and .30% for soybean meal, meat and bone meal and combination. All diets were calculated to meet or exceed the National Research Council recommendations for amino acids other than lysine. Gain and feed intake were measured over the treatment period. There was an effect (P less than .05) due to treatment on both average daily gain and gain/feed, but no effect calculated due to the independent variable of lysine intake for each of the lysine sources tested and the dependent variable of average daily gain or gain/feed. Response to the supplemental protein sources was linear. Gain and gain/feed were maximized when soybean meal fortified the basal diet. The data indicate that in weanling pigs to 17 kg body weight, lysine utilization from protein sources is not seriously affected by feeding the source in combination.(ABSTRACT TRUNCATED AT 250 WORDS)