An experiment was conducted to determine the effective dose of formalin killed (FK) fowl cholera (FC) vaccines prepared with virulent avian Pasteurella multocida (PM 38) serotype 1 (X-73) collected from the laboratory of the Department of Microbiology and Hygiene, BAU, Mymensingh. To determine the effective dose of vaccine, 7 weeks old 30 pigeons were immunized and each group consists of 5 birds. The groups are represented by A, B, C, D, E and F. The birds belonging to groups (A-E) were vaccinated with different doses of vaccine, after two weeks of first, second immunization and challenge experiment, blood was collected from all vaccinated birds, and serum was analyzed to determine antibody titer against P. multocida by passive hemagglutination test (PHA). The PHA titer after two weeks of first vaccination were 16±3.92, 17.6±3.92, 25.6±3.92, 32±8.76, 35.2±7.84 of group A,B,C,D and E, respectively at the dose of 0.2ml (0.26×108 CFU)/birds, 0.4ml (0.5×108 CFU)/birds, 0.8 ml (1.04×108 CFU)/birds, 1ml (1.3×108 CFU)/birds, respectively. The PHA titer of prevaccination and control birds was <4. The PHA titer after 2 weeks of second vaccination or boostering were 32±8.76, 35.2±7.84, 44.8±7.84, 57.6±18.66, 70.4±15.68, of group A,B,C,D and E, respectively. After 2 weeks of challenge infection, the mean PHA titer were 44.8±7.84, 51.2±7.84, 70.4±15.68, 102.4±15.68 and 140.8±31.34 of group A,B,C,D and E, respectively. In this experiment, the antibody titer of the vaccinated pigeons with 0.4, 0.6, 0.8 and 1ml per bird via intramuscular route were higher than that of the pigeons vaccinated with 0.4ml/bird, 0.6ml/bird, 0.8ml/bird and 1ml/bird were satisfactory in terms of protective potential against P. multocida. For prevention and control of avian pasteurellosis 0.4ml to o.6ml (0.52×108 CFU to 0.78×108 CFU)/birds of vaccine may be used instead of 1ml (1.3×108 CFU)/birds for better immunization of pigeon against fowl cholera infection.
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