The effect of non-phytate phosphorus and phytase levels on performance, egg and tibia quality, and pH of the digestive tract in hens fed higher-calcium-content diets

THe effect of three levels of non-phytate phosphorus (NPP) (3.0, 2.1, and 1.7 g/kg) and two levels of 3-phytase (F) (0 and 150 phytase units (FTU)/kg) together with a high dietary calcium concentration (approximately 41.0 g/kg) on the performance characteristics, egg quality, pH of the digestive tract, and tibia bone quality of ISA Brown hens housed in enriched cages was evaluated. THe diets with 3.0 g/kg of NPP with and without F and 2.1 g/kg of NPP with 150 FTU of F significantly increased egg production (P = 0.022) and daily egg mass production (P = 0.030). A low level of NPP decreased (P < 0.001) the body weight of hens at the end of the experiment. THe highest values of albumen height (P < 0.001), albumen index (P = 0.004), Haugh units (P = 0.001), and albumen percentage (P = 0.004) were associated with the diet with the low level of dietary NPP without F addition. THe low level of NPP with 3-phytase increased the calcium and phosphorus contents in eggshells (P = 0.002 and P = 0.050). THe lowest values of dry matter (P < 0.001) and ash content in tibia bone (P = 0.040) were measured for the hens fed the diet with 3.0 g/kg of NPP and 3-phytase supplementation. In addition, the low level of phosphorus without F addition increased (P = 0.031) the pH value in the small intestine to 6.21. In conclusion, 2.1 g of NPP with 150 FTU was found to be sufficient in the diet of hens in the middle of the laying cycle housed in enriched cages. But with respect to egg quality, higher calcium content decreased positive effect of F addition in diets with different levels of phosphorus.