Assessment of Vitamin E Supplementation As a Strategy to Mitigate Salmonella Prevalence in the Lymph Nodes of Feedlot Cattle

Abstract

ABSTRACT Salmonella can be harbored in peripheral lymph nodes (LNs) of cattle which can lead to contaminated ground beef. LNs present in beef fatty tissues can result in Salmonella presence in lean and fat trimmings used to produce ground beef. The objective of this study was to assess vitamin E supplementation as a strategy to mitigate Salmonella prevalence in the LNs of beef cattle. Two crops (warm and cool season) of one hundred calves each were split into two groups: (1) TRT- cattle (n = 100; warm n = 50; cool n =50) were fed an average of 1,348 IU/head/day, (2) CNTRL- cattle (n = 100; warm n = 50; cool n =50) were fed a typical feedlot ration of averaging 240 IU/head/day. Live weights were recorded on days 0 and 100 for each crop at the commercial feedlot location. All cattle underwent a typical feedlot finishing process. The average days on feed for each crop was 242 and 273 respectively. Carcass weights were recorded, along with liver and lung scores. Left and right superficial cervical and subiliac LNs (n = 764) were removed from all cattle and pooled by type (n = 382 LN samples). Out of the 382 LN samples, 186 confirmed as positive for Salmonella. The Salmonella percentages for positive LN samples collected in the warm season, crop 1, were 58.16% (57/98 LNs) and 61.22% (60/98 LNs) for CNTRL and TRT, respectively. The rate of Salmonella positive LN samples from CNTRL, harvested in the cool season, crop 2, was 23.33% (21/90 LNs) and TRT was 50.0% (48/96 LNs). TRT cattle had a higher prevalence rate of Salmonella-positive LNs for both seasons. Of the 186 samples that confirmed positive for Salmonella, fourteen unique serovars were identified. The most common serovars were S. Anatum (22.6%; 42/186), S. Kentucky (18.8%; 35/186), S. Muenchen (17.7%; 33/186), S. Montevideo (16.6%; 31/186), and S. Lille (7.0%; 13/186). Antimicrobial susceptibility results showed that Salmonella only one serovar was resistant, S. Montevideo.