Effects of increasing copper from either copper sulfate or combinations of copper sulfate and a copper-amino acid complex on finishing pig growth performance and carcass characteristics.

A total of 1,089 pigs (PIC 280 × 1050; initially 37.3 ± 2.8 kg) were used to determine the effects of increasing Cu provided from either CuSO4 alone or a 50:50 blend of CuSO4 and a Copper-amino acid complex (Cu-AA) on growth performance and carcass characteristics of finishing pigs. Pens of pigs were blocked by body weight; within blocks, pens were randomly allotted to one of six dietary treatments. The six dietary treatments consisted of a control diet which contained 17 mg/kg Cu from CuSO4 from the trace mineral premix, or the control diet with either added CuSO4 to provide 70 and 130 mg/kg total Cu or a 50:50 blend of Cu from CuSO4 and Cu-AA (CuSO4/Cu-AA blend) to provide 70, 100, and 130 mg/kg total Cu. Experimental diets were corn-soybean meal-dried distillers grains with solubles-based and fed in meal form in five phases (approximately 37 to 46, 46 to 63, 63 to 77, 77 to 103, and 103 to 129 kg body weight). From d 0 to 43, neither Cu source nor level influenced growth performance. From d 43 to 105, average daily feed intake (ADFI) decreased (P = 0.037) for pigs fed the CuSO4/Cu-AA blend compared to those fed added Cu from CuSO4 alone. Gain:feed ratio (G:F) tended to be improved (linear, P = 0.056) as Cu concentration increased. Overall, d 0 to 105, neither Cu level nor source influenced average daily gain (ADG). Pigs fed 70 or 130 mg/kg total added Cu from the CuSO4/Cu-AA blend had lower (P = 0.045) ADFI but G:F tended to be improved (P = 0.051) compared with those fed the same amount of total Cu from only CuSO4. Owing to the decreased ADFI and improved G:F of pigs fed the CuSO4/Cu-AA blend, carcass G:F also improved (P = 0.033) compared with those fed added Cu from CuSO4 alone. In conclusion, providing a 50:50 blend of CuSO4 and Cu-AA improved G:F on both a live and carcass weight basis compared to CuSO4 alone with no differences in ADG or carcass ADG observed.