中文摘要：

本试验主要研究不同的维生素A、D水平及其相互作用对肉鸡血清钙结合蛋白（CaBP）浓度与十二指肠和胫骨组织中CaBP mRNA表达的影响。采用4×4完全随机试验设计,选择8日龄健康AA雄性肉鸡384只按体重一致的原则分为16个日粮组,每组3个重复,每个重复8只鸡,试验期5周。维生素A设4个添加水平分别为1500、3000、15000和45000IU/kg,维生素D设4个添加水平分别为500、1250、2500和5000IU/kg。结果表明：1）随着日粮维生素A添加水平的增加,肉鸡血清CaBP含量、十二指肠和胫骨组织中CaBPmRNA表达量均呈现一次线性降低趋势（P=0.091,P=0.012,P=0.110）,其中以45000IU/kg维生素A组最低;2）随着日粮维生素D添加水平的增加,肉鸡血清CaBP含量和十二指肠组织中CaBP mRNA的表达呈现一次线性增加趋势（P=0.310,P=0.140）,其中以5000IU/kg维生素D组最高;3）维生素A、D相互作用对肉鸡血清CaBP浓度与十二指肠和胫骨组织中CaBP mRNA的表达均无显著的影响（P〉0.05）。试验结果提示,过量维生素A引起肉鸡骨骼代谢异常的机理是过量维生素A抑制了肉鸡组织的CaBP mRNA表达,尤其对十二指肠组织的CaBP mRNA的表达有显著的抑制作用,引起血清CaBP浓度的降低,进而引起钙磷代谢发生紊乱。过量维生素A对肉鸡组织CaBP mRNA表达的抑制作用可能与过量维生素A对维生素D的拮抗作用有关。

英文摘要：

The experiment was conducted to evaluate the effects of interaction between vitamin A and vitamin D on calcium-binding-protein （CaBP） concentration in serum,CaBP mRNA expression in tibia and duodenum of broilers. Three hundred and eighty four 8-day-old Arbor Acre male broilers with similar body weight were randomly allotted into 16 treatments with 3 replicates each and 8 chickens in each replicate. The trial lasted for five weeks. The 16 treatments were formulated by the addition of 1 500,3 000,15 000 and 45 000 IU/kg of vitamin A and the addition of 500,1 250,2 500 and 5 000 IU/kg of vitamin D to the basal diet in a 4×4 factorial arrangement. The results showed as follows： 1） the CaBP concentration in serum,CaBP mRNA expression in duodenum and tibia of broilers showed a downward tend of linear （P=0.091,P=0.012,P=0.110） with the added levels of dietary vitamin A,and the addition of 45 000 IU/kg vitamin A group showed the lowest results; 2） the CaBP concentration in serum and CaBP mRNA expression in duodenum showed a upward tend of linear （P=0.31,P=0.14） with the added levels of dietary vitamin D,and the addition of 5 000 IU/kg vitamin D group showed the highest results; 3） there is no significant interaction between vitamin A and vitamin D in CaBP content in serum and CaBP mRNA expression in tibia and duodenum of broilers （P〉0.05）. The results showed that the possible mechanism by which excess vitamin A caused abnormal skeleton metabolism was that large amount of vitamin A in diet inhibited the expression of CaBP mRNA,especially,the expression of CaBP mRNA in duodenum,and then induced a reduction of serum CaBP content,and resulted in abnormal metabolism of calcium and phosphorus. It was probably related to antagonistic action of high levels of vitamin A on vitamin D that excessive vitamin A may decrease CaBP mRNA expression of broilers.