Copper hydroxychloride improves growth performance and reduces diarrhea frequency of weanling pigs fed a corn–soybean meal diet but does not change apparent total tract digestibility of energy and acid hydrolyzed ether extract

Three experiments were conducted to determine effects of Cu hydroxychloride on DE and ME, apparent total tract digestibility (ATTD) of energy and acid hydrolyzed ether extract (AEE), and growth performance of pigs fed a diet based on corn and soybean meal (SBM). In Exp. 1, 80 weanling pigs (6.80 ± 1.69 kg) were allotted to 2 treatments with 4 pigs per pen and 10 pen replicates per diet. Pigs were fed a corn-SBM control diet that had Cu added to meet the requirement. A second diet was formulated by adding 150 mg Cu/kg from Cu hydroxychloride to the control diet. Both diets were fed for 4 wk. Results indicated that ADG, G:F, and final BW were greater (P ≤ 0.05) and fecal scores were reduced (P ≤ 0.05) for pigs fed the diet containing150 mg Cu/kg as hydroxychloride compared with pigs fed the control diet. In Exp. 2, 36 barrows (9.89 ± 1.21 kg) were randomly allotted to 3 dietary treatments and placed in metabolism crates. The control diet was based on corn and SBM and contained 20 mg Cu/kg. Two additional diets were formulated by adding 100 or 200 mg Cu/kg from Cu hydroxychloride to the control diet. Diets were fed for 28 d, with feces and urine being collected from d 9 to 14, d 16 to 21, and d 23 to 28. The DE and ME of diets and the ATTD of GE and AEE were not affected by dietary Cu concentrations, but increased (P < 0.01) by collection period. In Exp. 3, 150 pigs (10.22 ± 1.25 kg) were fed the same 3 diets as used in Exp. 2. Diets were provided on an ad libitum basis for 4 wk. Fecal scores were recorded, and on the last day of the experiment, blood samples were collected and tumor necrosis factor-α (TNF-α), IgA, blood urea N, total protein, and albumin were measured. Phase 1 ADG and G:F and final BW on d 28 were greater (P ≤ 0.05) for pigs fed diets containing 100 or 200 mg Cu/kg supplemented by Cu hydroxychloride compared with pigs fed the control diet. Pigs fed the diets supplemented with Cu hydroxychloride also had reduced (P ≤ 0.05) overall fecal scores and diarrhea frequency compared with pigs fed the control diet. However, no differences among treatments were observed for concentrations of TNF-α, IgA, blood urea N, total protein, or albumin. In conclusion, supplementation of Cu as Cu hydroxychloride to diets fed to weanling pigs improved growth performance and reduced diarrhea frequency, but this did not appear to be a result of increased digestibility of energy or AEE.