Significance of phytic acid and supplemental phytase in chicken nutrition: a review

Abstract

Phytic acid is an anti-nutritional constituent of plant derived feeds. As a reactive anion, it forms a wide variety of insoluble salts with minerals including phosphorus, calcium, zinc, magnesium and copper. Phytic acid is also known to form complexes with protein and proteolytic enzymes (pepsin and trypsin). Because of the lack of endogenous phytase enzymes that hydrolyze phytic acid; phosphorus, calcium, protein and other phytic acid bound nutrients are less available to poultry. Commercially-available microbial phytase has great nutritional significance and ecological importance. Poultry diets supplemented with microbial phytase result in improved growth performance and increased digestibility and availability of phytate bound phosphorous, calcium, zinc and copper. Microbial phytase supplementation has also been shown to increase ileal digestibility of crude protein and amino acids. The efficacy of supplemental microbial phytase depends on its rate of inclusion, dietary calcium and phosphorus ratio, vitamin D3, nature of diet, age and genotype of birds. Thus, microbial phytase can be used to exploit the inherent nutritional potential of feedstuffs for more economic and environmentally-friendly poultry production.