In another feeding trial using day-old turkey poults, seven levels of phytase were added to diets containing three levels of nonphytate phosphorus. The semi-purified diets contained SBM as the only protein source. Treatment differences were observed in gains and feed intakes. The high incidence of leg disorders and high mortality observed in the low nonphytate diet without added phytase declined with the addition of phytase. The ash percentage of toes and tibias increased as nonphytate phosphorus and phytase increased, the magnitude of the response to phytase increased as the level of nonphytate phosphorus increased, resulting in a nonphytate phosphorus by phytase interaction. Tibia shear force and stress responded in a similar manner to increasing levels of nonphytate phosphorus and added phytase. Results showed that 625 U of microbial phytase is equivalent to one g of phosphorus from deflourinated phosphate in turkey starter diets using soybean meal as the only source of phytate phosphorus. The response per 100 U of phytase decreased as the total amount of phytase added was increased.

V. Radindran, E.T. Kornegay, D.M. Denbow, Z. Yi and R.M. Hulet. 1995. Response of turkey poults to tiered levels of Natuphosr phytase added to soybean meal-based semi-purified diets containing three levels of nonphytate phosphorus. Poultry Sci. 74(11): 1843-1854.