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

The experiment was conducted to elucidate the effects of interaction between vitamin A and vitamin D on calcium and phosphorus metabolism and calcium-binding-protein gene expression in broilers. 384 8-day-old AA male broilers with similar body weight were randomly allotted into 16 treatments with 3 replicates in every treatment, with 8 broilers in every replicate. Broilers were fed four levels of dietary vitamin A (1500, 3000, 15000 and 45000IU/kg) and four levels of vitamin D ( 500, 1250, 2500 and 5000 IU/kg) in a 4×4 factorial arrangement. The results showed as follows:1) While dietary vitamin A level was 45000IU/kg, the bone ash content, bone calcium concentration, BMD (bone mineral density), and serum AKP (Alkaline Phosphatase) activity were significantly decreased compered with 1500IU/kg vitamin A level. Bone Phosphorus concentration was significantly increased compered with 1500IU/kg vitamin A level. While dietary vitamin A level was 15000IU/kg, the bone calcium concentration and serum AKP activity had the tendency to be decreased, the bone phosphorus concentration had the tendency to be increased.2) While dietary vitamin A level was 45000IU/kg, serum BGP concentration had the tendency to be significantly decreased compered with 1500IU/kg vitamin A level. While dietary vitamin A levels were increased from1500IU/kg to 45000IU/kg, serum CaBP concentration had the tendency to be linear function decreased, and serum PTH concentration had the tendency to be significantly linear function increased.3) While dietary vitamin A levels were increased from 1500 to 45000IU/kg, duodenum CaBP gene expression in broilers had the tendency to be significantly linear function decreased, and tibia CaBP gene expression had the tendency to be decreased, especially the 45000IU/kg vitamin A level was the lowest.4) While dietary vitamin D level was 5000IU/kg, serum VD3 concentration was significantly increased compered with 500IU/kg vitamin D level, While dietary vitamin D levels were increased from 500 to 5000IU/kg, serum BGP concentration had the tendency to be increased, but calcium concentration, phosphorus concentration in serum and tibia, serum AKP activity, BMD and serum CaBP, CT, PTH concentration had not significantly influence.5) While dietary vitamin D level increased from 500 to 5000IU/kg, CaBP gene expression in duodenum had the tendency to be increased, but CaBP gene expression in tibia had not significantly influence.6) There existed an interaction between vitamin A and vitamin D in calcium and phosphorous metabolism in broilers. 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 D.