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United States Department of Agriculture

Agricultural Research Service

Title: Feed Trucks As a Source of Salmonella Contamination

Authors
item Cray, Paula
item Hogg, A - LINCOLN, NE
item Gray, J - UNIV OSTEOPATHIC & HLTH
item Lorenzen, K - SUTTON VET CLINIC, NE
item Velasquez, J - IOWA STATE UNIVERSITY
item Von Behren, P - FREMONT, NE

Submitted to: Swine Health and Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 1997
Publication Date: N/A

Interpretive Summary: Infection of swine with Salmonella species results in millions of dollars in lost income to the swine industry. Additionally, swine are known carriers of Salmonella which may result in foodborne disease if consumers eat contaminated pork products. Animal feeds may be contaminated with Salmonella and may be one way in which swine become infected with Salmonella. Trucks that are used to transport feed may also be a source o contamination if they are not cleaned in between loads. We surveyed 22 swine feed trucks from 3 states to determine if they were a source of Salmonella contamination. Results indicate that 5/22 (22.7%) of the trucks were positive for Salmonella. More trucks containing meat, bone or fish meal were positive than those containing vegetable based feeds. Three of the 22 trucks were open to environmental contaminants. No trucks had been used to transport livestock within the past 30 days nor were any trucks cleaned or disinfected between loads. The presence of positive feed sample suggests that this would be a source of contamination for farm animals. This study shows that sampling feed trucks may be a good place to culture for Salmonella. Additionally, sanitation of trucks between loads may serve to reduce the possibility that feeds will become contaminated with Salmonella. This translates into fewer pigs which have Salmonella and ultimately means a more safe and wholesome product for the consumer.

Technical Abstract: Cary-Blair culture transport swabs were moistened in phosphate buffered saline (PBS) and used to swab approximately 25 different areas of the grain box on 22 different feed trucks in 3 states. In addition, a sample of the feed type was placed into PBS for culture. Swabs were cultured for the presence of Salmonella in both tetrathionate and GN Hajna broth followed by ysubculture into Rappaport Medium (R-10). Results from both swab and feed samples indicate that 5/22 (22.7%) of the trucks were positive for Salmonella. A total of 549 swabs were cultured and the rate of isolation was 0.7% (4/549 positive for Salmonella). Positive swabs were recovered from 3 trucks for a recovery rate of 13.6%. Feed was submitted for 17/22 trucks and Salmonella was recovered from 4 of 17 samples (23.51%). However, positive swabs and feed samples only matched for 2 trucks. Meat/bone meal, fish, and bone and meat meal separately were all positive for Salmonella. Soybean meal was also positive from the vegetable protein product group. More trucks containing meat, bone or fish meal were positive than those containing vegetable-based feeds. Three of the 22 trucks were open to environmental contaminants. However, only 1 truck had visible signs of environmental contamination which was identified as soybean mold. No trucks had been used to transport livestock within the past 30 days nor were any trucks cleaned or disinfected between loads. These data indicate that while sample prevalence of Salmonella in feed trucks is low (0.7%) the overall contamination rate for feed trucks is much higher (22.7%). The presence of positive feed samples suggests that this would be a source of contamination for farm animals.

Last Modified: 7/24/2014