EFFECT OF DIETARY LYSINE LEVELS FORMULATED BY ALTERING THE RATIO OF CORN - SOYBEAN-MEAL WITH OR WITHOUT DRIED WHEY AND L-LYSINE.HCL IN DIETS FOR WEANLING PIGS

A regional cooperative study (NCR-42 Committee) evaluated the efficacy of supplemental dried whey and L-lysine.HCl in a corn-soybean meal-based diet for weanling pigs. The experiment involved five research institutions using a total of 960 crossbred pigs weaned between 3 and 4 wk of age. The experiment was conducted as a randomized, complete block design in 15 replications with a minimum of two replicates per station. Two diets were formulated to contain either .95 or 1.10% lysine by altering the ratio of corn:soybean meal (C-SBM). Two other diets were formulated to the same lysine levels but with 20% dried whey (C-SBM-DW). Supplemental L-lysine.HCl was added to each diet mixture as another variable, increasing the lysine level of each diet by .15%. There were station effects (P < .01) for each trait, but no station x treatment interactions (P > .15). Feed intakes and weight gains were greater (P < .01) for pigs fed diets containing dried whey, and there was a greater response (26 vs 10%) to the C-SBM-DW diet that contained 1.10% lysine than to the C-SBM-DW diet at the .95% lysine level. Performance was not improved when L-lysine.HCI was added to either the .95 or 1.10% lysine C-SBM diets, and it elicited a small, but nonsignificant, gain response when it was added to the C-SBM-DW diets. These results suggest that gain and feed performance responses of weanling pigs improved when diets contained dried whey. Lysine was not the limiting factor in either the C-SBM or C-SBM-DW diet formulated to either .95 or 1.10%. Another factor in dried whey was assumed to be responsible for its growth promotion effect.