Dose-dependent effects of copper supplementation of nursery diets on growth performance and fecal consistency in weaned pigs

Pharmacological levels of dietary copper (150-250 mg/kg) improve growth performance in pigs, but the majority of Cu is excreted in the manure and may contribute to accumulation in the soil. This experiment with 4 levels of dietary Cu supplementation (15, 80, 120, and 160 mg/kg) from weaning to d 56 after weaning was conducted to determine the dose-dependent effects of dietary Cu on growth performance and fecal consistency in pigs. From d 56 to slaughter, all pigs received the same grower and finisher diets supplemented with 15 mg/kg Cu. Each treatment comprised 10 pens with 8 pigs each, mixed males and females, as experimental units. The pigs were housed in a nursery unit until d 40 after weaning and in a grow-finish unit thereafter. Growth performance and fecal consistency were determined in 2-wk intervals until d 56; thereafter, growth performance was monitored between d 56 and slaughter. The Cu supplementation linearly increased ADFI and ADG (P < 0.001) until d 40 and linearly increased G:F (P < 0.01) until d 28 of the nursery period. Copper supplementation linearly increased ADG (P = 0.024) from d 40 to 56. The proportion of piglets with loose feces and diarrhea was reduced with incremental dietary Cu in each 2-wk interval until d 56. The combination of our data with 5 published studies in weaned pigs and subsequent regression analysis showed that the inclusion of the European Union maximum Cu supplement of 160 mg/kg enhances the ADG by approximately 14%. Reduction of the Cu supplement to 120 mg/kg would reduce the ADG by 2 to 3% and increase the number of piglets with loose feces.