| The objectives of present studies were 1) to detect the immunoreactivity of yolk antibody against CCK by ELISA; 2) to elucidate the effect of CCK yolk antibody on growth performance and growth-related hormones in SD rats and AA broiler chickens; 3) to determine whether CCK yolk antibody can be absorbed intact from duodenum in rats; 4) to reveal the possible mechanisms involved in the effect of CCK yolk antibody on growth performance of broiler chickens.1. Preparation, detection and purification of CCK yolk antibody powder.The specific titer of CCK yolk antibody reached 1:12800 with ELISA. The processes of lyophilization and radicidation had no influence in the titer of CCK yolk antibody.Using water dilution combined with salting out, we isolated the immunoglobulin from the egg yolk. The purity of CCK yolk antibody was 83.8%. SDS-PAGE electrophoresis showed that the moleculer weight of CCK yolk antibody was 200 kDa.2. Effect of CCK yolk antibody powder on growth performance and secretion of related hormones in SD rats.One hundred and twenty male SD rats at 21 days of age were randomly divided into four groups, with dietary supplementation of CCK yolk antibody powder at the dosage of 0, 70, 150, 300 mg/kg, respectively. The body weight and food intake of rats were recorded regularly during the experiment. After 6 weeks, rats in 70 mg/kg treatment and control groups were sacrificed for blood sampling, liver, gastrocnemius muscle, geliac and peirenal fat were weighed.Results showed that 70 mg/kg of CCK yolk antibody powder significantly increased body weight and body weight gain of rats (P<0.05), whereas the other treatment groups at higher doses did not show significant differences in growth performance compared with control group (P>0.05). At the same time, the organ weight, organ index and food intake of rats had no changes (P>0.05). Seventy mg/kg of CCK yolk antibody powder increased serum insulin (P=0.067) and decreased serum leptin (P=0.068) concentrations in rats.3. Absorption of CCK yolk antibody from duodenum in the rats.To clarify whether CCK yolk antibody can be absorbed from duodenum in rats, ELISA and Western blot analysis were employed to detect the immunoreactivity and the chemical form of CCK yolk antibody in duodenal venous blood after gastric infusion of CCK yolk antibody. Fourteen adult male SD rats were divided at random into treatment and control groups. Two ml of CCK yolk antibody (150 mg/ml) or physiological solution (0.9% NaCl) was administered intragastrically to rats in treatment and control group, respectively. Duodenal venous blood was collected from duodenal venous catheters at the 2nd, 3rd and 4th hour after infusion.CCK yolk antibody was detected in the duodenal venous plasma of treatment group by ELISA at the 2nd and 3rd hour after administration with the titer of 1:128. Western blot analysis confirmed the finding of ELISA that intact CCK yolk antibody existed in duodenal venous plasma of treatment group. These results suggest that CCK yolk antibody can be absorbed or partly absorbed from duodenum in rats and play its role in systematic circulation.4. Effect of CCK yolk antibody powder on growth performance and secretion of related hormones and gene expression in broiler chicken.Two hundred AA broiler chickens were randomly divided into four groups, with basal diet supplemented with CCK yolk antibody powder at the dosage of 0, 50, 70, 90 mg/kg, respectively. The body weight and food intake of broiler chicken were recorded weekly during the experiment. After 42 days, broiler chickens were slaughtered for carcass analysis and blood sampling. The duodenums and hypothalamus of chickens in 50 mg/kg treatment and control groups were sampled for further analysis. Serum concentrations of insulin and leptin were determined by RIA. The total RNA was extracted from tissue samples to measure the abundance of CCK, CCK-A receptor (CCK-AR) mRNA expression by RT-PCR with p-actin as an internal standard.The results showed that CCK yolk antibody powder at 50, 70, 90 mg/... |
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