Role of microbial phytase in broiler nutrition- A review

During the past decade, the inclusion of microbial phytase in poultry diets has increased remarkably, mainly in response to heightened concerns over phosphorus (P) pollution of the environment. The capacity of this feed enzyme to release phytate-bound P and reduce P excretion is now well documented. Effectively, phytase is an alternative, economical P source and, as global phosphate reserves are not renewable, this is beneficial to their preservation. Alternatively, dietary phytate concentrations may be reduced by the inclusion of selected, low-phytate feedstuffs or dephytinised feed ingredients. There is a distinct possibility that phytate negatively influences protein and energy utilisation in poultry and, as these influences would be ameliorated by phytase. Responses in amino acid digestibilities following phytase supplementation are variable and the underlying mechanisms have not been completely understood. The impact of phytase on protein and energy utilisation may be more positive than generally realized, but this should become increasingly evident if greater phytate degradation rates can be achieved. The practical acceptance of microbial phytase in poultry diets will re-define nutrient requirements, particularly in relation to P and calcium, and increasingly contribute to ecologically sustainable poultry production in the future. This would be facilitated by a more fundamental research focus, which, arguably, has been lacking in the past.