Effects of a new recombinant phytase on performance and mineral utilization of laying ducks fed phosphorus-deficient diets

An experiment was conducted to evaluate the effects of a new phytase supplementation in Jinding laying ducks fed different concentrations of non-phytate P (NPP) on production performance, mineral retention, and bone and plasma minerals. A 14-wk experiment was conducted using 200-d-old female laying ducks. A total of 1,000 laying ducks were randomly allocated to 5 treatments and fed 5 diets: a control diet that contained an adequate concentration of NPP (0.45%) and 4 diets that were deficient in NPP (0.38, 0.32, 0.25, and 0.18%, respectively) but supplemented with phytase at 500 U/kg. Decreasing the NPP content from 0.45 to 0.18% in the diets with phytase supplementation had no detrimental effects on performance. However, Cu and Zn retention was significantly lower (P < 0.05) for laying ducks consuming the 0.18% NPP diet with phytase supplementation. Likewise, laying ducks fed the 0.18% NPP diet had a significant reduction in bone ash, Ca, P, and Cu contents, and in serum P and Cu (P < 0.05). Furthermore, the decrease in NPP content in the diet with phytase supplementation significantly increased (P < 0.05) P retention. Therefore, with the supplementation of this novel phytase at 500 U, it is possible to reduce dietary concentrations of NPP to 0.25% and maintain the normal performance of laying ducks.