An in vitro procedure was developed to simulate the digestion system of growing swine for the purpose of predicting phosphorus release from a corn-soybean meal diet. The procedure consisted of separate peptic and pancreatic digestion periods. The peptide digestion was carried out by incubating one gram of feed with 300 units of pepsin at pH 2.5 for 75 minutes. Pancreatic digestion was conducted at a pH of 6.0 dialyzing medium for 1-5 hours after the pepsin digesta were mixed with 2.4 mg of pancreatin. The in vitro phosphorus release responded linearly and quadratically to increasing concentrations of added phosphorus and microbial phytase, respectively. The recovery rate of added phosphorus averaged 98 percent. The in vitro release correlated (r+0.999) with in vitro phosphorus digestion and growth performance. The authors believe the method offers a valid, simple and economical method for predicting the enzymatic dephosphorylation of phytate in corn-soybean meal diets fed to growing swine.

Liu, J.Z., D.R. Ledoux and T.L. Veum. 1997. In vitro procedure for predicting the enzymatic dephosphorylation of phytate in corn-soybean meal diets for growing swine. J. Agric. Food Chem. 45(7):2612-2617.