Phytate and phosphorus utilization by broiler chickens and laying hens fed maize-based diets

Maize grain is primarily used as an energy source for poultry and other animals. Maize has relatively high phytate-P content and very low intrinsic phytase activity. Given that feed phosphates are produced from finite rock phosphate resources, a reduction in the use of feed phosphates in maize-based diets by increasing the utilization of plant P sources by animals is necessary to make poultry meat and egg production more sustainable. The utilization of P by poultry is affected by two intrinsic characteristics of maize: the concentration of inositol phosphates and the activity of the intrinsic phytase of the grain in the digestive tract. The objective of this review is to present data on the variation that exists in composition of maize relevant for P use and to address factors that influence P utilization in maize-based diets of poultry. Broiler chickens and laying hens have the potential to degrade phytate in the gastrointestinal tract, but this is depressed by high dietary Ca and P concentrations. Published values of phytate degradation in broilers are overall higher than those in laying hens. Differences also exist between broiler chickens and growing turkeys and Pekin ducks. The exogenous supplementation of microbial phytases and the introduction of transgenic high phytase maize in poultry diets are efficient not only for the improvement of phytate-P digestibility, production performance, egg quality and bone mineralization, but also for the reduction of P excreta to control environmental impact.