Effect of Organic Cu Supplementation on Growth Performance, Apparent Total Tract Digestibility (ATTD), and Tissue Mineral Composition in Nursery Pigs

A 28-d feeding trial was conducted to evaluate the effect of organic Cu supplementation on growth performance, ATTD, and tissue mineral concentrations for nursery pigs. A total of 160 crossbred weanling pigs (initial BW = 5.98 ± 0.53 kg) were blocked by BW and gender and then randomly allotted to 4 dietary treatments with 5 pigs/pen for 8 replicates. Dietary treatments were: 1) Control: corn-SBM based basal diet without Cu supplementation, 2) 80 ppm of Cu supplementation from organic Cu (MINTREX; Novus International, Saint Charles, MO), 3) 150 ppm of Cu supplementation from organic Cu, and 4) 150 ppm of Cu supplementation from CuSO₄. Two diet phases were used for d 0-14 (Phase 1) and d 14-28 (Phase 2). Pigs were slaughtered (1 pig/pen) at d 28 postweaning to collect bile, liver and duodenal mucosa. In Phase 2, the 150 ppm Cu groups had lower ADG than the control and 80 ppm of organic Cu groups (P < 0.05) regardless of Cu sources. In the results of ATTD, the 80 ppm of organic Cu group had the highest ATTD of ether extract (P = 0.10) but the lowest ATTD of Ca (P < 0.05) and ash (P = 0.07) with quadratic responses as organic Cu supplementation levels increased. The Cu concentrations in bile (P < 0.01, linear; 28.3, 28.9, and 52.1 mg/kg for 0, 80 and 150 ppm of organic Cu levels) and liver (P < 0.01, quadratic; 14.7, 17.4, and 63.9 mg/kg) at d 28 postweaning increased with increasing organic Cu supplementation levels in which the 150 ppm of organic Cu group had greater liver Cu concentrations compared with the 150 ppm of CuSO₄ group (P < 0.05; 63.9 vs. 39.9 mg/kg). Duodenum mucosal lipase activity tended to increase (P = 0.109, linear; 1,718, 1,928, and 2,250 U/kg for 0, 80, and 150 ppm of organic Cu levels) with increasing organic Cu supplementation levels. In conclusion, Cu supplementation had no benefits on growth performance, tended to increase ether extract ATTD and lipase activity but reduced Ca and ash ATTD. Copper deposition in bile and liver increased with Cu supplementation; Cu deposition in liver at d 28 postweaning was greater in the organic Cu group compared to the CuSO₄ group at the same supplementation level indicating that organic Cu had greater bioavailability relative to CuSO₄ in Cu deposition.