Abstract Two experiments evaluated the use of approximately 150 mg/kg of added Cu in nursery and finishing pig diets. In Exp. 1, 2,204 pigs (initially 5.3 ± 0.09 kg) were used in a 38-d study with 29 pigs/pen and 19 pens/treatment. Pens of pigs were allotted to four feeding strategies in a randomized complete block design. Strategies consisted of feeding duration of 150 mg/kg added Cu: 1) control with 17 mg/kg added Cu, 2) 150 mg/kg added Cu in phase 3, 3) 150 mg/kg added Cu in phases 2 and 3, and 4) 150 mg/kg added Cu in all phases. Treatment diets were fed based on feed budgets of 1.8 kg/pig for phase 1 (d 0 to approximately 10), 5.4 kg/pig for phase 2 (approximately d 10 to 24), and phase 3 was fed for the remainder of the trial (approximately d 24 to 38). Diets within each phase contained either 17 mg/kg (base) or the 17 mg/kg provided by the premix with an additional 150 mg/kg Cu from tribasic copper chloride (NexTrace TBCC, 58%, SAM Nutrition, Bloomington, MN). All diets contained 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg Zn in phase 2. In phase 2, pigs fed 150 mg/kg added Cu had greater average daily gain (ADG; P = 0.012) and average daily feed intake (ADFI; P = 0.021) than pigs fed the control diet. However, no differences were observed among strategies for overall performance. In Exp. 2, 2,160 pigs (initially 24.1 ± 0.60 kg) were used in a 110-d study with 27 pigs/pen and 20 pens/treatment. Pens of pigs were allotted to one of four treatments: base level of Cu or 150 mg/kg Cu from TBCC source 1 (NexTrace TBCC, 58%, SAM Nutrition, Bloomington, MN), TBCC source 2 (Intellibond C, 54%, Selko, Tilburg, Netherlands), and CuSO4 (25.2%, Phibro Animal Health Corp., Teaneck, NJ). All diets contained basal Cu from the premix with those containing added Cu containing an additional 150 mg/kg Cu from treatment sources. From d 0 to 56, pigs fed added Cu had greater ADG (P 0.001) and a tendency for increased ADFI and G:F (P ≤ 0.059) with no source differences. From d 56 to 110, no differences in growth were observed. Overall, the addition of 150 mg/kg Cu increased ADG (P = 0.018) and final weight (P = 0.008) and a tendency for increased ADFI (P = 0.072); however, there were no differences observed between Cu source. In summary, 150 mg/kg added Cu provided limited overall benefit in the nursery when 2,000 to 3,000 mg/kg of Zn were fed. In grow-finish pig diets, 150 mg/kg of added Cu improved growth performance regardless of source, with the greatest response during the early growing phase.
Swanson et al. (Mon,) studied this question.