IN-VITRO PROCEDURE FOR PREDICTING THE ENZYMATIC DEPHOSPHORYLATION OF PHYTATE IN CORN-SOYBEAN MEAL DIETS FOR GROWING SWINE

An in vitro procedure was developed to simulate the digestive system o f growing swine for the purpose of predicting phosphorus release from corn-soybean meal diets. The procedure consisted of separate peptic an d pancreatic digestion periods. Peptic digestion was carried out by in cubating 1.0 g of feed sample with 3000 units of pepsin at pH 2.5 for 75 min. Pancreatic digestion was conducted in a pH 6.0 dialyzing mediu m for 1-5 h after the pepsin digesta were mixed with 2.4 mg of pancrea tin. The in vitro P release responded linearly and quadratically (p < 0.0001) to increasing concentrations of added P and microbial phytase, respectively. The recovery rate of added inorganic P averaged 98%. Th e in vitro P release correlated (r = 0.999) with in vivo P digestibili ty and growth performance. In conclusion, this in, vitro procedure is a valid, simple, and economical method for predicting the enzymatic de phosphorylation of phytate in corn-soybean meal diets fed to growing s wine.