Long Story From Past to Present: Calcium, Phosphorus, and Phytase –A Review

Calcium (Ca) and phosphorus (P), two main elements, have vital physiological and metabolic roles in animal bodies. Accurate comprehension of the interaction of these two elements and their value in various resources helps to obtain their optimal formulation in poultry diets. Hence, in previous studies, the hormonal axes controlling Ca and P homeostasis have been primarily investigated. However, to estimate Ca and P requirements in modern broiler chickens, in addition to growth performance, other parameters such as Ca and P digestibility, bone strength, and excretion into the environment should also be considered. Since a large amount of P in poultry feed ingredients is bound to phytate, phytases are added to poultry diets to release the P from phytate. However, many nutritionists need clarification on what dose of dietary phytase is required to release the maximum phytate P and how phytase activity will be optimized. Therefore, the present review study has attempted to explore the factors that affect the digestibility of different sources of Ca and P. In addition, the effect of excess dietary Ca on phytase activity and studies related to superdosing of phytase in broilers are provided. Finally, the values of phytate P in standard poultry feed ingredients and the latest update of the studies on determining Ca and P requirements are summarized.