Effect of microbial phytase on production performance of White Leghorn layers fed on a diet low in non-phytate phosphorus

Abstract

1. An experiment with 150 White Leghorn layers was conducted to examine the effect of microbial phytase supplementation of low non-phytate phosphorus (NPP) diets on egg production, eggshell quality, bone mineralisation and retention of nutrients at 32–48 weeks of age.

2. Four isonitrogenous and isocaloric diets were formulated to contain 1·2, 1·8, 2·4 and 3·0 g NPP/kg diet with the two lowest NPP (1·2 and 1·8) supplemented with microbial phytase (Biofeed Phytase, India) at 500 FTU per kg diet. Each diet was offered ad libitum to 5 replicates of 5 layers throughout the experiment.

3. Body weight gain was reduced significantly in the layers fed on the 1·2 g/kg NPP diet as compared to those given diets containing 1·8–3·0 g/kg. Addition of phytase to the 1·2 g/kg diet significantly enhanced the body weight and was comparable with those given diets containing 1·8–3·0 g/kg NPP.

4. No additional advantage resulted from enhancing the NPP levels beyond 1·8 g/kg or adding phytase to a diet containing 1·8 g/kg NPP.

5. Hen d egg production, food intake, food efficiency, shell weight, shell thickness, shell strength and tibia strength followed the same trends as above. However, adding phytase to the 1·8 g/kg NPP diet significantly enhanced tibia ash. Egg weight, specific gravity and Haugh units were influenced by neither NPP concentration nor phytase supplementation.

6. Adding phytase to the 1·2 g/kg NPP diet significantly enhanced nitrogen and phosphorus retention.

7. It was concluded that addition of 500 FTU of microbial phytase/kg diet can allow the reduction of NPP content to 1·2 g/kg in the layer diet, eliminate inorganic phosphorus supplementation and results in significant reduction of nitrogen and phosphorus excretion without affecting the production performance of layers.