Prevalence of Salmonella organisms in swine feed.
OBJECTIVE
To test feed and feed ingredients on swine farms for Salmonella organisms and to analyze data from these farms to determine risk factors associated with Salmonella organisms in the feed and feed ingredients.


METHODS
Epidemiologic survey and retrospective case-control study.


METHODS
30 swine farms.


METHODS
Samples of feed and feed ingredients and information regarding herd characteristics were collected from 30 swine farms. Samples were tested for Salmonella organisms, and data compiled from herd information forms were examined for associated risk factors between herd characteristics and isolation of Salmonella organisms.


RESULTS
Salmonella organisms were isolated from 36 of 1,264 (2.8%) feed and feed ingredient samples and from 14 of 30 (46.7%) farms. Thirteen Salmonella sp serotypes and 2 untypeable isolates were cultured. Recovery of Salmonella organisms from at least 1 feed or feed ingredient on a farm was significantly associated with 6 herd characteristics (lack of bird-proofing, using farm-prepared feed for finishing-age pigs rather than purchased feed, and housing pigs in facilities other than total confinement in the growing, finishing, gestating, and breeding stages of production, respectively). Isolation of Salmonella sp was not associated with a history of salmonellosis on a farm.


CONCLUSIONS
Salmonella organisms were readily isolated from samples of feed and feed ingredients, illustrating that salmonellae are ubiquitous in a farm environment. Implementing sanitary and pest-control measures continues to be a prudent recommendation. Salmonella serotypes found in feed and feed ingredients have the potential to cause disease in pigs that consume the feed or, ultimately, in people that consume pork.
Harris
I T
IT
Enteric Diseases and Food Safety Research Unit, USDA, Ames, IA 50010, USA.
Fedorka-Cray
P J
PJ
Gray
J T
JT
Thomas
L A
LA
Ferris
K
K
D000821:Animal Feed / Q000382:microbiology*; D000822:Animal Husbandry; D000818:Animals; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005516:Food Microbiology; D012189:Retrospective Studies; D012475:Salmonella / Q000145:classification / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology; D012703:Serotyping / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology