Effects Of Vitamin A, Vitamin D And Vitamin E On Growth Performance, Immun Functions And Metabolism Of Calcium And Phosphorus In Broilers

The experiment was conducted to elucidate the effects of VA ,VD and VE on growth performance, immune functions and metabolism of calcium and phosphorus in broilers. 576 1-day-old AA male broilers with similar body weight were randomly allotted into 24 treatments with 4 replicates in every treatment, with 6 broilers in each replicate. Broilers were fed four levels of dietary VA (1500, 3000, 15000 and 45000IU/kg) , three levels of VD (500, 1250 and 5000IU/kg) and two levels of VE (15 and 1500 IU/kg) in a 4×3×2 factorial arrangement. The results showed as follows:1) Diet containing VA 3000 IU/kg would result in better growth rates. While dietary VA level was 1500 or 45000IU/kg, growth rate was significantly decreased. VA influenced immune functions in a dose-dependent manner. Diet containing VA 15000IU/kg would result in better immune functions, while diet containing VA 1500 or 45000IU/kg decreased immune functions.2) While dietary VD levels increased from 500 to 5000IU/kg, there was no significant difference on growth rate. However, 1250IU/kg VD level was better in daily gain than others. Diet containing VD 5000IU/kg would result in better immune functions. When dietary VE levels were 15 or 1500IU/kg, there were no significant differences in the growth rate and immune functions. However, the addition of 1500IU/kg VE to the diet was better than 15IU/kg in thymus or bursal index.3) There existed interactions between VA, VD and VE in immune functions of broilers, which suggested that there were synergistic or antagonistic effects between VA and VD or VE respectively.4) For broilers fed the diet containing 45000IU/kg, the serum AKP (alkaline phosphatase) activity and BMD (bone mineral density) were significantly decreased; bone calcium concentration, bone ash content, serum BGP and CT concentrations tended to significantly decrease. The addition of 15000IU/kg VA in diets would tend to decrease the above items to a different extent. The dietary VA and VE levels had no significant effects on the above items.5) The dietary VA and VE levels had no significant effects on serum BGP, CaBP, ?PTH, VD3 and CT concentrations.6) There existed an interaction between VA and VD in serum AKP which suggected that there was an antagonistic effect between 45000IU/kg VA and VD. There existed an interaction between VA and VE in bone calcium concentration.7) While dietary VA level was increased from 1500 to 45000IU/kg, VA concentrations in serum, liver and kidney and VE concentration in liver were significantly increased; VE concentrations in kidney tended to significantly increase, and the addition of 15000 or 45000IU/kg in diets had better effect. But high doses of VA significantly decreased VE concentrations in serum, and the addition of 15000 or 45000IU/kg VA to the diet would be more effective than others.8) Serum VE concentration in diet containing VE 1500IU/kg was significantly increased compaired with 15IU/kg VE. The dietary VD levels had no significant effect on serum VA, VE and kidney VA concentrations, While dietary VD level increased from 500 to 5000IU/kg, liver VA concentration significantly decreased.9) There existed interactions between VA and VE, VD in serum VE and liver VA, VE concentrations, which suggested that there were antagonistic effects between VA and VD or VE.10) The result suggested that dietary VA was excess while dietary VA level was 45000IU/kg, and the addition of 15000IU/kg VA was probably excessive, the addition of 1500IU/kg VA was probably deficient for broilers.The adequate requirements of broilers were 3000IU/kg, 5000IU/kg and 15IU/kg in VA,VD and VE.