Evaluation of an autogenous Salmonella bacterin and a modified live Salmonella serotype Choleraesuis vaccine on a commercial dairy farm

Objective-To compare the efficacy of a Salmonella bacterin and a modified l ive 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 CI) strain 54 (SC54) vaccine, group-2 cows (150) were vaccinated on enrollment and 30 days later with a Salmonella ser. Mont evideo (serogroup C1) bacterin, and group-3 cows (150) served as unvaccinat ed controls. One gallon of colostrum harvested from the first 80 cows to ca lve was fed to each calf. Outcome assessments included fecal shedding of Sa lmonella spp for the first 10 days after parturition (cows) or birth (calve s), milk production, involuntary culling rate, mastitis incidence, antimicr obial 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 calv es that received colostrum from those cows, compared with the other groups, and vaccination was specifically associated with less shedding of serogrou p C1 salmonellae. Production data were similar among groups. Conclusions and Clinical Relevance-Vaccination of pregnant cows with an aut ogenous Salmonella bacterin had no effect on fecal shedding of salmonellae, whereas vaccination with a modified live S Choleraesuis vaccine reduced th e frequency of fecal shedding of serogroup C1 salmonellae during the peripa rtum period. A commercial S Choleraesuis vaccine licensed for use in swine may be more efficacious than autogenous Salmonella bacterins on dairies inf ected with serogroup C1 salmonellae.