Objective—To compare the efficacy of a Salmonella
bacterin and a modified live Salmonella ser.
Choleraesuis vaccine on a commercial dairy.
Animals—450 cows in late gestation and 80 calves.
Procedure—Group-1 cows (n = 150) were vaccinated
once with a modified live S Choleraesuis (serogroup
C1) strain 54 (SC54) vaccine, group-2 cows (150) were
vaccinated on enrollment and 30 days later with a
Salmonella ser. Montevideo (serogroup C1) bacterin,
and group-3 cows (150) served as unvaccinated controls.
One gallon of colostrum harvested from the first
80 cows to calve was fed to each calf. Outcome
assessments included fecal shedding of Salmonella
spp for the first 10 days after parturition (cows) or birth
(calves), milk production, involuntary culling rate, mastitis
incidence, antimicrobial use, and mortality rate.
Results—Salmonellae were isolated from 306 of 309
(99%) cows and 64 of 74 (86.5%) calves. Shedding
frequency was less in SC54-vaccinated cows and
calves that received colostrum from those cows,
compared with the other groups, and vaccination was
specifically associated with less shedding of
serogroup C1 salmonellae. Production data were similar
Conclusions and Clinical Relevance—Vaccination of
pregnant cows with an autogenous Salmonella bacterin
had no effect on fecal shedding of salmonellae,
whereas vaccination with a modified live
S Choleraesuis vaccine reduced the frequency of
fecal shedding of serogroup C1 salmonellae during
the peripartum period. A commercial S Choleraesuis
vaccine licensed for use in swine may be more efficacious
than autogenous Salmonella bacterins on
dairies infected with serogroup C1 salmonellae. (Am
J Vet Res 2001;62:1897–1902)