Nutritional And Physiological Effects Of Active Immunization Against Cholecystokinin In Laying Hens

This study explored active immunization against cholecystokinin in layinghens and the effect of nutrition and physiology.The control group was injected 100u g of HAS.The two treatment groups were injected l00u g and 200 u g of CCK respectively. Twelve hens were allotted into three treatment groups with four replicates per treatment and one layer per replicate. The immunization procedure included one initial injection and three boosters. Serum samples were collectd before immunization and one week after immunization. The eggs were collectted when the antibody tilter of serum was l:16.The antibody tilters of serum and yolk were examined with enzyme linked immunosorbent assay (ELISA).The performance, nutrient digestibility ,the development of pancreas and gallbladder, the activity of trypsin and the levelof hormones after immunization were examined. Finally, 160 1-d old Avian broilers were used to examine the effects of dried eggyolk containing cholecystokinin antibody on the growth performance and feed efficiency.The result showed active immunization against cholecystokinin resulted in development of high antibody tillers in serum and yolk,decreased the level of cholecystokinin in blood.After the first booster injection, the antibody tillers almost reached peak level.The development of gallbladder and pancreas were not affected by CCK immunization. The specific activity of trypsin was increased in treated group (CCK). Active immunization had no effect to growth hormone, insulin and leptin in serum. The performance of layers was not affected by CCK immunization. Significant improvements of average daily gain and feed efficiency in broilers of 1-42 days havebeen observed with the feeding of dried eggyolk containing cholecystokinin antibodies at 100mg per kg of feed.It is concluded that active immunization against cholecystokinin in laying hens has no negative impact on the physiology of hens and results in the production of eggyolk with high content of CCK antibody, which, when included in the diet of broilers at 100 mg/kg, could improve significantly the growth performance and feed efficiency.