A 20-week feeding study was conducted to evaluate the effects of phytase supplementation of a corn-soybean diet containing 1.4 percent tricalcium phosphate. Dietary microbial phytase was added at the rate of 500U/kg. Egg production, egg weights, and feed consumption were significantly increased with the phytase addition, however, feed conversion ratios were similar for the various treatments. Retention of calcium, phosphorus, magnesium, iron and zinc were greater in the phytase-supplemented groups. Excretion of ash, phosphorus and zinc was significantly higher for the control diet with 1.4 percent tricalcium phosphate level. The researchers concluded that supplementation of corn-soybean diet with microbial phytase improved egg production and can reduce the supplemental tricalcium phosphate level in the diet without affecting egg production and egg quality. Significant reduction of phosphorus excretion can be achieved with microbial phytase additions.

Um, J.S. and I.K. Paik. 1999. Effects of microbial phytase supplement on egg production, eggshell quality, and mineral retention of hens fed different levels of phosphorus. Poultry Sci. 78(1):75-79.