Active immunization of cows with a Salmonella typhimurium mutant bacterin-toxoid and the passive transfer of anti-core-antigen antibodies in colostrum

37 normal Holstein or Guernsey cows in their last 6 weeks of gestation were injected with either a placebo or Salmonella typhimurium mutant bacterin-toxoid. The vaccine stimulated a significant increase in the mean log2 anti-core-antigen serum antibody titres from 10.73 to 12.15 while there was no significant increase in serum antibody titres in placebo treated cows. There was a significant difference between the colostral mean anti-core-antigen antibody log2 titres of the placebo, 12.22, and vaccinated, 13.18, cows. The mean log2, serum antibody titres of suckled calves at 24 h of age from the placebo and vaccinated groups were 9.20 and 10.64 respectively and significantly different. It was concluded that cows vaccinated with bacterin-toxoid in the last 6 weeks of gestation seroconverted in terms of anti-core-antigen antibodies and that they passively transferred significantly higher levels of these antibodies through colostrum to their calves.