Study On Effects Of Supplementation Of Different Levels Of Cholecalciferol And Phytase In Lower Inorganic Phosphorus Diet Of Layers

In this paper, we studied the effects of supplementation of different levels of cholecalciferol(VD3) and phytase in lower inorganic phosphorus diet of layers at early stage. Three hundred HL layers of 23-week-old with an equal weight were randomly assigned to 10 groups. One group was control received a diet containing 0.37% of inorganic phosphorus plus 1400IU/kg VD3. Other groups were fed with a lower inorganic phosphorus (0.17%) diet supplemented with combination of 700, 1400, 2100 IU/kg VD3 and 200, 300, 400U/kg phytase. The results indicated that supplementation of different levels of VD3 and phytase under the condition of lower inorganic phosphorus diet of layers at early stages: (1) increased intake, body weight gain, egg production, egg production rate, egg weight, and feed conversion ratio; reduced break soft egg rate. (2) increased the egg shell strength, egg white height and Hafu unit, reduced the egg shell thickness. (3) increased tibia ash content of layers at early stage, increased phosphorus retention. (4) increased utilization of calcium, inorganic phosphorus, phytate phosphorus, zinc, iron and copper; reduced contents of them in the excretion. In conclusion, it is recommended that the suitable addition to a lower inorganic phosphorus diet for layers during 20 to 30 weeks old is 400U/kg phytase and 1400IU/kg VD3.