Abstract：In this study, the four repeats of chicken CCK-33 gene were successfully amplified by PCR. The 4CCK-33 fragment was inserted into plasmid pBCX to obtain recombinant plasmid pBCX-4CCK33. The recombinant plasmid was conducted into E.coli BL-21 to induce 4CCK-33 gene fusion expression. The fusion protein band with molecular weight of 53ku was detected on the SDS-PAGE gel; the peak expession level of fusion proteins occupied 30.08% of the total bacterial protein. What’s more, most fusion proteins were soluble. Western blotting showed that the expression products can specifically reacted with the antisera of CCK-8. The purified fusion proteins were used as antigen to prepare oil-emulsion vaccines, and the laying hens were immunized. ELISA results indicated that the vaccine can resulted in immune response. 82-day old pigs were inactively immunized with yolk powder containing CCK antibodies. The results showed that pigs fed diets with dried yolk powder containing CCK antibodies at the level of 100 g/t showed significant higher average daily gain and feed intake than the control group, with increase by 6.64% and 8% respectively.
