Effect of phytase supplementation on performance of broilers chickens fed diets with graded levels of phosphorus and calcium

One possibility to measure the extra-phosphoric effect of exogenous phytase is to use a higher concentration of this enzyme in the diets not limiting in phosphorus, to be sure that any observed effect is not caused by an increase in phosphorus digestibility. However, it is important to know how the requirements of the bird relate to the phosphorus content of the basal diet, because when the basal diet is very deficient in phosphorus all of the responses observed were likely attributable to phosphorus release. The literature tends to be consistent in that and describes the requirement for optimum growth rate in birds until 21 days of age between 0.45 and 0.5 % avP. Recent work suggests that there is a case for improved performance in response to higher inclusion rates of phytases when phosphorus is not limiting, suggesting this is linked more to extra-phosphoric effects (COWIESON et al., 2011). The present study was conducted to evaluate response to higher phytase doses when series of diets varying in inorganic phosphorus content was used. 6Phytase supplementation was evaluated in broiler chickens fed different phosphorus content diets based on maize and soybean meal, focusing on performance, phosphorus utilization and bone mineralization.