Effect of different phosphorus intakes on phosphorus balance and performance of layers during peak production
Two experiments were conducted to determine the effect of different phosphorus supplies on phosphorus balance and performance of high performance layers. Both experiments were conducted with 72 HyLine layers (18 birds/treatment; 3 birds/cage). Hens were fed diets containing 2.5; 2.0; 1.5 and 1.0 g/kg non-phytate phosphorus (NPP). The calcium content was maintained constant at 32.5 g/kg. In the balance trial, the hens were 45 weeks of age (25 week of production). At the beginning of the performance trial the birds were 45 weeks old and were fed for 12 weeks. Absolute P retention was calculated subtracting the mean P excretion in the excreta from the P intake. Relative P retention was calculated absolute P retention dividing by P intake. Decreasing dietary NPP levels reduced P excretion in the excreta. Relative P retention was not influenced by levels of NPP. Decreasing dietary NPP reduced absolute P retention and P balance. Hens fed 1.5 and 1.0 g/kg NPP showed the lowest P balance at 43 and 39 mg/d, respectively, which was still adequate for the birds. Diets had no effect on feed intake, egg weight and feed per egg mass (P≥0.05). As NPP decreased from 1.5 to 1.0 g/kg, egg production and egg mass decreased (P≤0.05). It was concluded that dietary P content can be reduced up to 1.5 g/kg NPP without influencing the level of production, and at the same time the environment is also alleviated.