Effects Of Vitamin A On Growth Performance And Immune Organs And Metabolism Of Calcium And Phosphorous In Broilers

The study was conducted to investigate the effects of vitamin A (VA)on growth performance, immunity indexe and metabolism of calcium(Ca) and phosphorus(P) in broilers. 300 1-day-old AA mixed-sex broilers were randomly allotted into 5 treatments with 6 replicates in each treatment, with 10 broilers in each replicate. The trial period was 42d. The basal diet was mainly composed of corn and soybean. Broilers were fed five levels of dietary VA (1500, 3000, 9000, 15000 and 45000 IU/kg) in a single factorial arrangement.The results were showed as follows:1. Dietary VA would affect broiler in growth performance. During 1to 21 days, the average daily gain of group 9000 IU/kg significantly incresed, compared to the other groups (P<0.05), the diets containing VA 15000 IU/kg significantly increased feed conversion efficiency (P<0.05), group 45000 IU/kg significantly decresed the average daily gain and feed conversion efficiency. During 22 to 42 days, the average daily gain of group 15000 IU/kg significantly increased, group 3000 IU/kg significantly incresed feed conversion efficiency. During 1to 42 days, the average daily gain of group 9000 IU/kg significantly incresed and feed conversion efficiency increased for broilers fed the diets containing VA 3000 IU/kg.2. Dietary VA would affect broiler in immunity indexe. On 21 day, immune organs (thoracic gland, spleen, bursa of Fabricius) of group 15000 IU/kg developed best(P<0.05), immune organs of broiler group 45000 IU/kg analosis, immune function subsided(P<0.05). On 42 days, index of thoracic gland and spleen of broiler group 3000 IU/kg was best (P<0.05), bursa of Fabricius index of broiler group 15000 IU/kg was best(P<0.05).3. Dietary VA would affect broiler in development and strength of ossature significantly(P<0.05). Content of Ca in serum significantly decreased with ugmentation of dietary VA (P<0.05). Content of P in serum has increased, calcium and ash content of tibia decreased, content of P in tibia significantly increased, activity of AKP in serum breakdown.