Growth Performance, Phosphorus Balance, and Bioavailability of Phosphorus in Pigs Fed High Available Phosphorus Corn and Phytase

Phytase has been shown to consistently improve the bioavailability of phytate phosphorus for pigs. However, only about 60 to 70% of the phytate P in a corn-soy diet is made available when supplemented with an optimal phytase dose. The use of high available P (HAP) should provide an additional strategy for improving the bioavailability of phytate P in pigs. In experiments 1 and 2, growth performance and utilization of P were compared in pigs fed high available P or normal corn with or without phytase. Weight gain and feed efficiency were expectedly depressed in the diet containing normal corn without phytase; supplementation with phytase improved these performance criteria. The addition of phytase to HAP corn diets produced a numerical improvement in weight gain. Supplementing the normal corn diet with phytase improved P digestibility and retention. Adding phytase to HAP corn gave a numerical increase in phosphorus digestibility and retention. Phosphorus digestibility and retention in HAP corn were increased 28% and 34%, respectively. The bioavailability of P in HAP and normal corn relative to mono-sodium phosphate was assessed in experiment 3. Estimates of P bioavailability from HAP and normal corn when plasma P was regressed on supplemental P intake was 46 and 33%, respectively.