Study On The Suitable Inclusion Level Of Yolk Powder Containing Cholecystokinin-specific Antibody In Broiler Diet

This study used the coupled compound of cholecystokinin-8(CCK-8) and carrierprotein(HSA) as antigen to immunize laying hens actively, the purpose lied in researchingthe effect of active immunization against cholecystokinin on the performance of layinghens and the production regularity of cholecystokinin-specific antibody in yolk. Thevalency of cholecystokinin-specific antibody in admixed yolk was determined through theprocedure of enzyme linked immunosorbent assay(ELISA). The yolk powder was used indiets of 960 1-d-old Avian broilers with different addition level, the purpose was toinvestigate the effect of yolk powder containing cholecystokinin-specific antibody ongrowth performance and the nutrients digestibility, accordingly to determine the suitableaddition level. Two experiments included in this study:Purpose of the first experiment was to product yolk powder containingcholecystokinin-specific antibody. This experiment comprised 60 270-day-old healthyLohmann Brown laying hens in 3 group randomly, including control group, HSAimmunization group and CCK immunization group. The immunization procedure includedone initial injection(200μg/ml/hen) and three boosters(100μg/ml/hen)with 21dinterval. Food intake, laying rate and egg weight were examined during the wholeimmunization period,meanwhile, the production regularity of cholecystokinin-specificantibody in yolk was also monitored.The yolk powder was producted through freezedrying pre-processing eggs collected which reached the suitable antibody valency, thendetermined the antibody valency of yolk powder with enzyme linked immunosorbentassay.The second experiment was conducted to evaluate the effect of different level yolkpowder containing cholecystokinin-specific antibody added in basal diet on growthperformance and nutrient digestibility of broilers.960 1-day-old Avain broilers wereallotted randomly into 8 treatments with 8 replicated of 15 broilers.Experiment wasdivided into 2 periods which lasted 6 weeks.Broilers were fed basal diet,basaldiet+50mg/kg aureomycin, basal diet+80mg/kg yolk powder containing HSA antibody andyolk powder containing CCK-specific antibody in diet with different level(40,80,120, 160,200mg/kg). At the 43th day, one broiler of each replicate were selected and subgroupedrandomly to conduct the metabolism test and collect the excreta through the plasticsenvelope which sutured in anus.Results indicat that: Acive immunization against cholecystokinin in laying hens resultedin the development of high CCK-specific antibody valency in yolk, ELISA experimentshowed the valency of yolk powder containing CCK-specific antibody was 1:512. Aciveimmunization against cholecystokinin in laying hens could improve food intake, layingrate and average egg weight, but not apparent in food intake. There was an improvingtendency effect of yolk powder containing CCK-specific antibody added in broiler diet ongrowth performance and nutrient digestibility, as the result of this experiment showed80mg/kg yolk powder containing CCK-specific antibody included in basal diet had a betterraising effect on broilers.