The effects of copper source and concentration on growth performance, carcass characteristics, and pen cleanliness in finishing pigs.

A total of 1,143 pigs (PIC 337 × 1050, initially 25.1 ± 0.03 kg BW) were used in a 111-d study to determine the effects of copper sulfate (CuSO; Prince Agri-Products, Quincy, IL) or tribasic copper chloride (TBCC; IntelliBond C; Micronutrients, Indianapolis, IN) on growth performance, carcass characteristics, and pen cleanliness. Pens of pigs were allotted to 1 of 6 dietary treatments, balanced on average pen weight in a randomized complete block design with 25 to 28 pigs per pen and 7 replications per treatment. Treatments included a corn-soybean meal-based diet (corn-soy), a high-by-product diet with 30% distillers dried grains with solubles and 15% bakery meal (by-product diet), and the by-product diet with 75 or 150 mg/kg added Cu from CuSO or TBCC. All diets contained 20 mg/kg Cu from CuSO in the trace mineral premix. At the conclusion of the trial, a digital photo of each pen was taken to allow 3 independent observers to score manure texture and buildup and to assess pen cleanliness prior to power washing. Furthermore, the time required to power wash each pen was also measured. Overall, pigs fed the by-product diet tended to have increased ADFI ( = 0.083) and had decreased G:F ( = 0.005) compared to those fed the corn-soy diet. No Cu source × level interactions or Cu source differences were observed ( > 0.05). From d 0 to 71, pigs fed increasing Cu had increased (quadratic, < 0.05) ADG, d 71 BW, and ADFI. From d 71 to 111, pigs fed increasing Cu tended to have increased ADFI (linear, = 0.068) and decreased G:F (quadratic, = 0.056). Overall (d 0 to 111), increasing Cu increased (linear, < 0.01) ADG, final BW, and ADFI (quadratic, = 0.026). Hot carcass weight increased (linear, = 0.023) by 2.4 kg with increasing Cu. Increasing Cu also increased loin depth (linear, = 0.019) and percentage lean (quadratic, = 0.024). Manure buildup and wash time (s/pen) increased ( < 0.05) for by-product diet pens compared to corn-soy pens; however, neither wash time nor pen cleanliness were influenced by added Cu. In summary, increasing dietary Cu in high-by-product diets improved growth and feed intake, resulting in increased final BW and HCW for pigs fed both Cu sources, without influencing pen wash time.