Efficacy of a copper-lysine complex as a growth promotant for weanling pigs.

Eight 28- or 35-d experiments involving, 1,301 crossbred pigs weaned at 30 +/- 2 d of age (7.0 to 7.9 kg initial weight) were conducted to evaluate the efficacy of a Cu-lysine complex (CuLys; CuPLEX 80 in Exp. 1 to 5, and CuPLEX 100 in Exp. 6 to 8) at dietary concentrations of 50, 100, or 200 ppm as a growth promoter for weanling pigs. CuPLEX 80 contained 50% Cu in the complexed from (1 mol Cu:2 mol lysine) and 50% Cu as CuSO4.5H2O (CuSO4). All the Cu in CuPLEX 100 was in the complexed form. In general, the addition of Cu from CuSO4 or either CuLys source improved pig performance. Overall, averaged across Cu sources, there were no differences between 100 and 200 ppm of Cu in the magnitude of improvement over controls for daily gain (14.0 vs 14.3%), daily feed (12.1 vs 10.7%), or feed:gain ratio (1.6 vs 3.0%). Averaged across levels of Cu supplementation, the percentage improvements from CuLys additions were greater than those for CuSO4 for growth rate (16.8 vs 11.5%; P < .03) and feed intake (14.1 vs 8.7%' P < .01), but not for efficiency of feed utilization (2.2 vs 2.4%). These trends were similar for both sources of CuLys. Liver Cu concentrations of pigs receiving 200 ppm of Cu in the totally complexed form (CuPLEX-100) were lower (P < .025) than concentrations in those receiving 200 ppm of Cu from CuSO4 (111 vs 221 ppm).(ABSTRACT TRUNCATED AT 250 WORDS)