Although phosphorus is plentiful in soybean meal, the majority of this phosphorus is in the form of phytic acid and is largely unavailable to poultry and swine. Several research groups have included phytase enzymes in feed formulations to increase the availability of phosphorus. Another approach to improving phosphorus availability is to genetically engineered soybeans to express a fungal phytase. Agracetus researchers inserted a fungal phytase gene in soybeans and researchers at Virginia Polytechnic Institute and State University tested the transformed soybean using a chick assay. Male broilers were fed a basal diet containing 0.20 percent nonphytate phosphorus and supplemented with fungal phytase or with raw soybeans expressing recombinant phytase. The results indicated that dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and phosphorus digestibility. With the exception of phosphorus digestibility, which was less for the supplement phytase compared to the transformed soybeans, there were no differences in response to phytase sources for several measurements. This study indicated that phytase can improve broiler performance when provided either as a commercial supplement or in the form of transformed soybeans.

Denbow, D.M., an co-workers. 1998. Soybeans transformed with a fungal phytase gene improve phosphorus availability for broilers. Poultry Sci. 77:878-881.