Immune response to clostridial vaccines in sheep with special reference to passively acquired cl welchii types B and D antitoxin in lambs

ABSTRACT

Field trials in sheep and lambs were carried out with Cl. welchii type B vaccine used alone or in combination with Cl. welchii type D. Effective responses were obtained and there was no observable interference when antigens were combined nor did passive Beta antitoxine or epsilon antitoxin prevent response to Cl. welchii type B toxoid or Cl. welchii type D toxoid in lambs. Moreover complete passive protection against lamb dysentery and pulpy kidney diseases occurred up to 8 weeks of age in lambs born to ewes inoculated with the routine dose of 2 ml. Cl. welchii type B or Cl. welchii type D before lambing, whether this was a booster dose or the second dose of the primary series. In a small selected group 30% were still protected at 16 weeks of age. Doubling the dose of vaccine significantly raised the titres of ewes at parturition and also increased the percentage of passively protected lambs to 50%