Efficacy of an inactivated broth-grown Pasteurella multocida bacterin in ducklings
1988
Singh, R. | Teo, T.P. (Primary Production Dept. (Singapore). Central Veterinary Laboratory)
A formalin inactivated Pasteurella multocida (PM) serovar A:1 bacterin for use in ducklings was produced in 10 litre glass bottles containing 6-8 litres of aerated tryptose broth. The growth of PM exceeded absorbance 1.5 at 525 nm, the cell density was greater than McFarland tube No.10 and the viable bacterial count more than 10(10) colony forming units (CFU)/ml. In laboratory experiments ducks administered a 1 ml + 1 ml dose of the Central Veterinary Laboratory (CVL) bacterin subcutaneously (s/c) at 7 day old (d.o) and 17 d.o developed immunity that lasted upto market age of 56 d.o. In field trials the CVL bacterin gave better protection than the imported PM serovar A:1 bacterin which has been widely used on local duck farms since 1985. Only 6/24 (25 %) of the flocks vaccinated with the CVL bacterin has a PM infection compared to 8/19 (42.1 %) of the flocks immunized with the imported bacterin. In a large scale field trial on approximately 38,000 ducks the mortality was 9.3 % in ducks immunized with the CVL bacterin compared to 16.2 % in the imported bacterin vaccinated control group
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