It is well known that limestone is used as a major source of inorganic calcium (Ca) in commercial poultry diets, as well as microbial phytase to improve phosphorus (P) and Ca utilisation, and to reduce P excretion into the environment.  The efficacy of commercial microbial phytase to degrade phytate (myo-inositol hexakisphosphate, or IP6) in the…