VACCINATION SCHEDULES TO RAISE ANTIBODY CONCENTRATIONS AGAINST EPSILON-TOXIN OF CLOSTRIDIUM-PERFRINGENS IN EWES AND THEIR TRIPLET LAMBS

The objective of this experiment was to compare vaccination schedules for ewes and their lambs to raise antibody concentrations to epsilon-t oxin of Clostridium perfringens, the causative agent of enterotoxemia. Half of 200 Finnsheep x Dorset ewes were vaccinated with C. perfringe ns type D toroid vaccine 3 wk before lambing. Serum samples were obtai ned from 20 ewes that were to be vaccinated and 20 ewes that would rem ain unvaccinated before treatment and at wk 2, 1, and 0 before the sta rt of lambing. Antibody concentrations in sera of unvaccinated ewes re mained at 2 IU/mL, but they peaked in vaccinated ewes at 15 IU/mL by w k 1 before lambing. Lambs from each of the first 13 and the first 14 s ets of triplets from vaccinated and unvaccinated ewes, respectively, r eceived one of three vaccination treatments: no vaccine (control), vac cination on d 1 and 21 of age, or vaccination on d 21 and 42 of age. A ntibody concentrations declined in sera of vaccinated ewes from 8.5 IU /mL immediately after lambing to 3 IU/mL 12 wk later. Vaccination of l ambs did not increase sera antibody concentration. However, prepartum vaccination of ewes significantly increased lamb antibody concentratio ns (19 IU/mL) compared with lambs reared by unvaccinated ewes (2 IU/mL ). Vaccination of ewes resulted in lambs with higher antibody concentr ations until wk 10 postpartum. Concentrations declined to .6 IU/mL in all lambs at 12 wk. Because concentrations of .2 IU/mL may be protecti ve, these results indicate that vaccination of ewes before lambing imp arts passive protection in lambs to 12 wk of age, whereas vaccination of young lambs provides no added protection.