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 ev aluate the efficacy of a Cu-lysine complex (CuLys; CuPLEX 80(TM) in Ex p. 1 to 5, and CuPLEX 100(TM) in Exp. 6 to 8) at dietary concentration s of 50, 100, or 200 ppm as a growth promoter for weanling pigs. CuPLE X 80 contained 50% Cu in the complexed form (1 mol Cu:2 mol lysine) an d 50% Cu as CuSO4.5H(2)O (CuSO4). All the Cu in CuPLEX 100 was in the complexed form. In general, the addition of Cu from CuSO4 or either Cu Lys source improved pig performance. Overall, averaged across Cu sourc es, there were no differences between 100 and 200 ppm of Cu in the mag nitude of improvement over controls for daily gain (14.0 vs 14.3%), da ily feed (12.1 vs 10.7%), or feed:gain ratio (1.6 vs 3.0%). Averaged a cross levels of Cu supplementation, the percentage improvements from C uLys 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 f or efficiency of feed utilization (2.2 vs 2.4%). These trends were sim ilar for both sources of CuLys. Liver Cu concentrations of pigs receiv ing 200 ppm of Cu in the totally complexed form (CuPLEX-100) were lowe r (P < .025) than concentrations in those receiving 200 ppm of Cu from CuSO4 (111 vs 221 ppm). Based on these results, the Cu-lysine complex was as effective as, and in some cases more effective than, CuSO4 in enhancing pig performance and resulted in lower liver Cu stores. Also, 100 ppm of Cu was as efficacious in stimulating growth as 200 ppm of Cu, regardless of source of Cu.