Digestive utilization of minerals by weanling pigs fed copper- and phytase-supplemented diets

The digestive utilization of minerals in Cu- and phytase supplemented diets by weanling pigs was investigated in an experiment with a 3 x 2 factorial arrangement of treatments. Three levels of Cu (0, 60 and 120 mg kg(-1) as CuSO4:5H(2)O) and two levels of phytase activity (0 and 1500 units kg(-1)) were added to a corn-soybean meal basal diet. Seventy-two pigs (gilts:barrows, 1:1) with an average initial weight of 9.7 kg received the six diets for 21 d, after which 36 of the pigs were used in an 8-d mineral balance study. Phytase supplementation of diets increased serum P, Zn and Mg concentrations but reduced serum Cu concentration. The addition of Cu to the diets produced serum concentrations of minerals similar to Cu-unsupplemented diets. Absorption and retention of Ca and P were both slightly increased in pigs fed the phytase-supplemented diets compared with pigs fed diets that did not contain phytase. Addition of phytase to the diet that was not supplemented with Cu doubled (P < 0.1) Cu retention. Copper supplementation of diets did not affect absorption and retention of Ca, P, Zn, and Mg but increased absorption and retention of Cu and Mn. Results indicate that addition of phytase to P-supplemented and Cu-unsupplemented diets improves digestive utilization of P and Cu.