Long-Term Effects of Dietary Source and Level of Copper on Reproductive Performance, Nutrient Digestibility, Milk Composition, and Tissue Trace Mineral Concentrations of Sows

The objective of the experiment was to determine the effects of dietary copper (Cu) source and level on sows for up to 4 parities. A total of 31 crossbred gilts (55 ± 2 d post-breeding; initial BW 189 ± 13 kg) were assigned to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement with a completely randomized design. The first factor was 2 Cu sources [copper sulfate (CuSO₄) or tribasic copper chloride (TBCC)] while the second factor was 3 supplemented Cu levels (20, 120, or 220 mg/kg). Sows continued on their respective dietary treatment throughout gestation and lactation. Samples were collected from sows at late gestation (feces; d 98 to 102) and lactation (feces and milk; d 15 to 17). Upon completion of 3 or 4 parities, sows were slaughtered for tissue collection. Dietary treatments did not affect sow BW changes during gestation and lactation or litter size (P > 0.23). Sows fed TBCC diets had greater adjusted weaning weight of litter (58.51 vs. 53.40 kg, P = 0.14) and piglets (6.80 vs. 6.33 kg, P = 0.07), as well as adjusted lactation weight gain of litter (44.41 vs. 40.14 kg, P = 0.10) and piglets (5.16 vs. 4.76 kg, P = 0.05) when compared to sows fed CuSO₄. Increasing dietary Cu level linearly increased live born piglet weight (P = 0.06). Sows fed TBCC diets had lower apparent total tract digestibility (ATTD) of ether extract in gestation (P = 0.01), but greater ATTD of dry matter, nitrogen, and phosphorous in lactation (P < 0.05) when compared to those fed CuSO₄. Increasing Cu levels linearly increased ATTD of dry matter in lactating sows (P = 0.02). Sows fed TBCC diets had greater concentrations of fat, protein, gross energy, and total solids (P < 0.10) in milk than sows fed CuSO₄. Increasing Cu levels increased levels of milk fat and Cu (linear, P < 0.05); but linearly decreased lactose and Zn levels (P < 0.05). Sows fed TBCC diets had lower liver concentration of Cu (P = 0.04), but higher concentrations of iron and manganese (P < 0.05) than sows fed CuSO₄. Moreover, liver Cu concentration increased with increasing dietary Cu levels (linear and quadratic, P < 0.05). In conclusion, sows fed TBCC diets had improved litter performance compared to sows fed CuSO₄; and higher Cu levels resulted in greater birth weight of piglets.