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Reduced Burden of Salmonella enterica in Bovine Subiliac Lymph Nodes Associated with Administration of a Direct‐fed Microbial
Author(s) -
Vipham J. L.,
Loneragan G. H.,
Guillen L. M.,
Brooks J. C.,
Johnson B. J.,
Pond A.,
Pond N.,
Brashears M. M.
Publication year - 2015
Publication title -
zoonoses and public health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.87
H-Index - 65
eISSN - 1863-2378
pISSN - 1863-1959
DOI - 10.1111/zph.12187
Subject(s) - propionibacterium freudenreichii , salmonella , salmonella enterica , veterinary medicine , biology , lymph , medicine , zoology , food science , bacteria , genetics , fermentation , psychiatry
Summary Despite effective food safety interventions within abattoirs, Salmonella enterica remains a common contaminant of raw ground beef. Research has recently implicated peripheral lymph nodes ( PLN s) as a potential route by which Salmonella contaminates ground beef. This study examined the efficacy of using Lactobacillus animalis (formerly designated Lactobacillus acidophilus ; NP 51) and Propionibacterium freudenreichii ( NP 24), at 10 9 cfu/head/day, as a direct‐fed microbial ( DFM ) in feedlot cattle diets to control Salmonella within PLN s. Two studies were conducted in which cattle were randomly allocated into either control or DFM treatment groups. Diets of treated cattle were supplemented with 10 9 cfu/head/day of the DFM , while control groups received no DFM supplementation. During slaughter at abattoirs, one subiliac lymph node ( SLN ) per carcass was collected from 627 carcasses from one study and 99 carcasses from the second study. Lymph nodes were cultured to estimate the presence and concentration of Salmonella . In the first study, effects of DFM supplementation varied across slaughter days. On the first and second slaughter days, prevalence was reduced by 50% ( P = 0.0072) and 31% ( P = 0.0093), respectively. No significant difference was observed on slaughter day three ( P = 0.1766). In the second study, Salmonella was 82% less likely ( P = 0.008) to be recovered from SLN s of treatment cattle. While a greater relative risk reduction was observed in the latter study, absolute risk reductions were similar across studies. A significant reduction in the concentration of Salmonella in SLN s ( P < 0.0001) on a cfu/g and cfu/node basis was also observed in cattle administered NP 51 and NP 24 in the first study; in the second study, too few quantifiable SLN s were observed to facilitate meaningful comparisons. The results indicate that NP 51 and NP 24 supplementation may aid in reducing the prevalence and concentration of Salmonella in SLN s and, therefore, serve as an effective control measure to reduce Salmonella in ground beef products.