Effect of Suboptimal Levels of Non-Phytate Phosphorus and Exogenous Phytase on Precaecal Digestibility of Phosphorus and Calcium in Laying Hens
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The precaecal digestibility of phosphorus and calcium in laying hens was evaluated at two dietary levels of non-phytate phosphorus (NPP; 1.58 and 2.03 g/kg) and two levels of exogenous 3-phytase (F; 0 and 300 phytase units (FTU)/kg). A total of 192 ISA Brown hens were used for the study, and were housed in enriched cages (8 per cage). At the end of the experiment, which was the peak of the egg production, the content of the posterior half of the ileum from each hen was collected. The lower level of NPP significantly (P < 0.05) improved the precaecal phosphorus digestibility coefficient. There was no significant difference in the amount of absorbed phosphorus between the lower and the higher level of NPP. The level of NPP with supplementation of exogenous phytase had a significant effect (P < 0.001) on the concentration of phosphorus in ileum, while the higher level of NPP increased phosphorus concentration in the ileum and phytase decreased phosphorus content in the ileal digesta. The phytase had no significant effect on phosphorus precaecal digestibility. There was no significant effect of the both factors, level of NPP, and exogenous phytase on the daily calcium intake, the amount of absorbed calcium, the content of calcium in ileal digesta, and on the precaecal digestibility of calcium. However a significant effect (P < 0.05) of the interaction between NPP and phytase was observed on the amount of absorbed calcium and on the precaecal digestibility coefficient. It can be concluded that the estimation of phosphorus ileal digestibility depends on the level of dietary phosphorus.