Location: Food and Feed Safety Research
Title: Salmonella diversity and burden in cows on and culled from dairy farms in the Texas High Plains Authors
|Loneragan, Guy -|
|Thomson, Daniel -|
|Mccarthy, Rebecca -|
|Webb, Hattie -|
|Daniels, Angela -|
|Trojan, Sara -|
|Rankin, Shelly -|
|Brashears, Mindy -|
Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 18, 2012
Publication Date: June 4, 2012
Citation: Loneragan, G.H., Thomson, D.U., McCarthy, R.M., Webb, H.E., Daniels, A.E., Edrington, T.S., Nisbet, D.J., Trojan, S.J., Rankin, S.C., Brashears, M.M. 2012. Salmonella diversity and burden in cows on and culled from dairy farms in the Texas High Plains. Foodborne Pathogens and Disease. 9:549-555. Interpretive Summary: Dairy cattle may contain the bacteria Salmonella that can make people sick. Feces were collected from 706 animals culled from 9 dairies that were marketed for later human consumption. Fecal samples were cultured for Salmonella. Salmonella was recovered from all dairies in our study, and herd-level factors resulted in substantial variation in the prevalence and amount. In addition to other management factors, use of a Salmonella vaccine by some of the dairies indicates this may be a useful aid in the control of Salmonella in cows culled from dairies and intended for human consumption.
Technical Abstract: The objective of this study was to further characterize the epidemiology of Salmonella carried by dairy cows culled from herds in the Texas High Plains and marketed for human consumption. Feces were collected from 706 animals culled from a convenience sample of 9 dairies. In addition, individually paired fecal and hide samples were collected from 70 healthy milking cows on 3 of the dairies. Up to 3 colonies were selected from samples collected from culled cows and up to 10 colonies were selected from samples collected from healthy milking cows. Isolates were serotyped and susceptibility to antimicrobial drugs was determined. Salmonella was recovered from 32.6% of culled cows and prevalence varied among dairies (p < 0.01) and over time (p < 0.01). Whole-herd use of a vaccine containing siderophore receptors and porin proteins explained (p = 0.05) a portion of the observed variation. Prevalence among herds that practiced whole-herd vaccine was 8.0% compared to 36.8% among herds that did not use this vaccine. The majority (88.6%) of isolates were pansusceptible or resistant to 1 drug. Of those 3.1% of isolates resistant to more than 4 drugs, all were S. Newport and all were recovered from 1 dairy. Up to 3 and 4 serotypes were recovered from individually paired fecal and hide samples, respectively. Salmonella Montevideo was recovered more frequently (p < 0.01) from hide samples, S. Cerro was recovered more frequently (p < 0.01) from feces, and S. Muenster was recovered similarly across the sample matrices (p = 0.55). Salmonella was recovered from all dairies in our study and herd-level factors resulted in substantial variation in burden. In addition to other management factors, use of a siderophore receptor and porin protein-containing vaccine may be a useful aid in the control of Salmonella in cows culled from dairies and intended for human consumption.