Effects Of Vitamin A And Vitamin E On Calcium And Phosphorus Metabolism And Calcium-binding-protein Gene Expression In Broilers

The experiment was conducted to determine the effects and interaction of feeding different levels of vitamin A and vitamin E on calcium and phosphorus metabolism and calcium-binding-protein gene expression in broiler chickens. 384 1-day-old broilers with similar body weight were randomly allotted into 16 treatments with 3 replicates in each treatment, with 8 broilers in each replicate. Broilers were fed four levels of dietary VA (1500, 3000, 15000, and 45000IU/kg) and four levels of vitamin E ( 5, 15, 150, and 1500 IU/kg) in a 4×4 factorial arrangement. The results showed as follows:1. Feeding the high levels of VA ( 45000IU/kg) significantly decreased the tibia ash content, tibia calcium content , tibia mineral density and significantly depressed serum AKP (Alkaline Phosphatase) activity of broiler chick(sP<0.05).The addition of 15000 IU/kg VA in diets would tended to decrease above items to different extent. The addition of 1500 IU/kg VE would tend to increase serum calcium content and tibia mineral density(P<0.10).2. While dietary vitamin A levels were increased from1500 IU/kg to 45000IU/kg, serum CaBP(calcium-binding protein),BGP(bone gla-protein) concentrations in serum had the tendency to be decreased(P<0.10),and serum CT (Calcitonin )concentration was significantly decreased(P<0.05), The results showed that dietary vitamin A supplementation enhanced serum PTH content in a linear dose-dependent manner(P<0.05), and that serum VD3 content would also decrease to different extent.3. There were no significant influences in BGP,CT and VD3 concentrations of serum while dietary vitamin E level were increased from 5 to 1500IU/kg. The addition of 1500 IU/kg vitamin E in diet would evidently improve serum CaBP concentration and would tend to depress PTH content and tend to increase vitamin D3. content in serum.4. While dietary vitamin A levels were increased from1500IU/kg to 45000IU/kg, CaBP(calcium-binding protein) gene expression in duodenum had significantly decreased(P<0.05), especially the 45000IU/kg vitamin A level was the lowest. While dietary vitamin A levels were increased, CaBP gene expression in tibia concentration had the tendency to be linear function decreased. especially the 45000IU/kg vitamin A level was also the lowest.5. While dietary vitamin E level was 1500IU/kg, serum calcium content and tibia mineral density would tend to increase(P<0.10). While dietary vitamin E level increased from 5 IU/kg to 1500IU/kg, the serum CaBP and VD3 concentrations of serum tend to increase.6. While dietary vitamin E level increased from 5 to1500IU/kg, CaBP gene expression in duodenum had the tendency to be increased(P<0.10), but CaBP gene expression in tibia had not significantly influence(P>0.05).7. There existed an interaction between vitamin A and vitamin E in calcium and phosphorous metabolism in broiler chicks. High level of vitamin A resulted in changes of calium and phosphorus metabolism of bone, which was related to the antagonism between vitamin A and vitamin E.