Enzymatic Relationships in the Utilization of Soybean Oil Meal Phosphorus by the Rat

Abstract

It has been shown that soybean oil meal phosphorus, which was 58% phytin or phytic acid phosphorus, was utilized by the rat without a ration-borne heat labile phytase. Heating the rations at 98°C. for 48 hours did not depress the utilization of the phosphorus. A method for the determination of phytase activity was developed which revealed the presence of a phytase in the small intestinal mucosa and in the intestinal contents of the rat. The optimum pH of this enzyme was found to be pH 7.8. Although the addition of magnesium ions to a crude enzyme preparation caused an increase in total phosphorus liberated, it did not stimulate the action of phytase. Phytase activity was observed in the small intestines of rats of all ages and in the small intestines of rats receiving several different rations. Solvent or expeller soybean meals failed to show any phytase activity at pH 5.2 or at pH 7.8. Phytase activity was observed in the small intestinal mucosa of the chicken, pig and cow. From these studies it would appear that the phytin or phytic acid phosphorus of soybean oil meal was made available by the action of intestinal phytases.