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Salmonella bacteria can result in adverse health effects in both cattle and humans. In some cattle
populations, Salmonella can affect health and production efficiency, but these effects are poorly
defined for feedlot cattle. Salmonella are a significant cause of foodborne illness in the U.S., but
human salmonellosis has been associated with many foods. Salmonella can be found on hides and in
feces of cattle at harvest, which occasionally may lead to the contamination of beef. Consumption
of contaminated beef has been associated with occasional human infections and few multi-state
outbreaks due to drug-resistant Salmonella.
<P> Preharvest interventions that would reduce the prevalence of Salmonella in the feedlot environment
may enhance beef safety, and also may improve cattle health and performance. One potential
preharvest strategy employs a novel vaccine technology, based on Siderophore Receptor and Porin
(SRP®) proteins, which has been shown to be efficacious in controlling Salmonella in certain
production systems. Although a commercial Salmonella Newport SRP® vaccine may decrease fecal
shedding and improve the health and performance of animals, there are no data on the effects of the
vaccine in a commercial feedlot environment. Therefore: objectives were 1) to determine
the effect of the commercially available Salmonella Newport SRP® vaccine on prevalence of
Salmonella in feces of commercial feeder cattle, and 2) to determine the potential vaccine effects on cattle health and performance outcomes in the feedlot
Findings: Steer calves (average weight 546 lbs) originating from livestock markets and ranches in KS, OK, TX and SD were enrolled into the two treatment groups of the study. Overall, Salmonella were
recovered from 10.75% (215/2000) of the fecal samples. Salmonella were recovered from
all ten pairs of pens, with overall prevalence (all sampling times combined) ranging from 1.5% to
22%. Salmonella prevalence was affected by sampling time (P < 0.01), but not by vaccine treatment (P
= 0.89). There was no significant treatment by sampling time interaction (P = 0.12).