Clostridial vaccination efficacy on stimulating and maintaining an immune response in beef cows and calves.

Experiments were conducted to determine the efficacy in stimulating and maintaining an immune response in the presence of maternal antibodies, compare the extent of the anamnestic responses to revaccination, and compare the maternal antibody response of 2- or 5-mL clostridial vaccination. In Exp. 1, 118 nursing calves were randomly assigned to receive a 2-mL (Alpha-7, A7) or a 5-mL clostridial vaccine (Ultrabac 7; UB7) at 50.4 +/- 15.30 (X +/- SD) d of age (d 0 = date of calving). Calves were revaccinated with the same treatment on d 170. Blood samples were collected from 10 calves of each treatment group on d 50, 170, and 191 to determine antitoxin units for Clostridium perfringens type C (PC) and D (PD) and agglutination titers for Cl. chauvoei (CC). The A7-treated calves tended (P < .10) to have higher PC units on d 170, an increased rate of change in PD units from d 170 to d 191 (P < .06), and a tendency (P < .10) for enhanced CC titers on d 191 compared with UB7-treated calves. In Exp. 2, 109 pregnant cows and 83 pregnant heifers were randomly assigned within a 2 x 2 x 2 factorial design. The main effects were dam age (cow or heifer), dam treatment (A7 or UB7), and calf treatment (A7 or UB7). Dams were vaccinated with A7 or UB7 d 124 prepartum (d -124) and d 53 after birth. At d 53.4 +/- 12.88, calves were vaccinated with A7 or UB7 (d 53). Calves were revaccinated with the same treatment on d 173. Blood samples were collected from 10 dams per treatment group on d -124, 53, and 173 and from their calves on d 53, 173, and 194. Cows had higher antitoxin levels for PC (P < .01) and PD (P < .05) than heifers. The A7-treated dams had higher (P < .01) PD units on d 53 and d 173 and CC on d 173 than did UB7-treated dams. Calves from A7-treated cows had higher (P < .03) PD units on d 53 than calves from UB7-treated cows. The A7-treated calves had higher titers for CC (P < .01) on d 173 than did UB7-treated calves, and this enhanced level seemed to continue to d 194 (P < .08). In conclusion, titers for clostridial diseases in 50- to 53-d-old calves can be enhanced if dams are vaccinated approximately 4 mo before calving, and 120 d between clostridial vaccinations seems to be too long for adequate protection.