Influence of Phytase on Calcium Utilization in Commercial Layers

Abstract

Several studies have shown that microbial phytase improved bioavailability of phytate phosphorus and reduced the need for inorganic phosphorus in layer diets. However, limited work is available concerning the influence of phytase on availability of other nutrients, especially Ca. The objective of this study was to determine the influence of phytase on Ca utilization in Hy-Line W-36 hens. This experiment utilized three levels of dietary Ca (3.1, 3.4, and 3.7%) and two levels of phytase (0 and 300 phytase units/kg diet) with 0.3% nonphytate phosphorus (NPP). Three additional treatments with 3.4, 3.7 and 4.0% Ca with 0.4% NPP were also included in this study to compared results. Increasing dietary Ca from 3.1 to 3.7% resulted in a significant linear increase in eggshell and bone quality. Phytase supplementation (300 phytase units/kg) significantly increased egg specific gravity (ESG) during the first 6 wk. Subsequently, phytase significantly increased ESG of hens fed 3.4% Ca, but not of those fed 3.1 and 3.7%. Phytase improved bioavailability of Ca and eggshell quality at the marginal Ca level of 3.4% as indicated by improved ESG.