Location: Meat Safety & Quality Research
Title: Examination of predictors of Salmonella enterica contamination in cattle feedlot environments Authors
|Loneragan, Guy -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 15, 2014
Publication Date: March 4, 2014
Citation: Harhay, D.M., Arthur, T.M., Schmidt, J.W., Wang, R., Kalchayanand, N., Bosilevac, J.M., Edrington, T.S., Loneragan, G., Wheeler, T.L. 2014. Examination of predictors of Salmonella enterica contamination in cattle feedlot environments. [Abstract] Beef Industray Safety Summit. Available: www.bifsco.org/attendees.aspx. Technical Abstract: Objective: To identify a “predictor” or “environmental marker” that can be used to estimate Salmonella prevalence in a given feedlot environment. Further, to examine the correlation between environmental Salmonella contamination, Salmonella fecal shedding status, and prevalence of Salmonella in peripheral lymph nodes. Experimental Treatments: Samples were collected from three feedlots located in BIFSCo Regions 3 and 5. Hide swab, fecal swab and environmental samples were collected from May to August 2013. On average 20% of cattle per pen were sampled from a total of 10 pens, and average pen size was 224 head. Hide and fecal samples were collected from cattle restrained in a squeeze chute, as they were being processed for growth promoter implant (approximately 75 days post arrival at the feed yard). Environmental samples from 5 pens per yard, including pen floor surface material, water tank, feed, and flies, also were collected from each of the participating yards. Approximately 90 days post-implant, cattle were shipped to a commercial abattoir for harvest and a subset of cattle sampled at implant were selected for lymph node and fecal swab collection. All samples were analyzed for Salmonella prevalence and level. For each carcass, six lymph nodes were collected, three from each carcass half, including the superficial cervical, subiliac, and popliteal. Key Results: 1) Results indicate that Salmonella fecal shedding status does not appear to correlate with peripheral LN contamination within a given animal. Instead, peripheral LN contamination appears to be related to the percent of Salmonella super shedders present in a pen, and the resultant hide contamination levels of cohorts within that pen. 2) Enumerable levels of Salmonella in tank water and measureable prevalence in feed are potential indicators of aberrantly high levels of Salmonella in a given feedlot. How can this information can be applied in the industry? The data collected suggest that aberrantly high levels of Salmonella contamination on cattle hides (defined here as hides contaminated at = 103 CFU/100cm2) are correlated with peripheral lymph node contamination with Salmonella. Analysis of feedlot environmental samples including surface material, tank water, feed and flies, suggests that enumerable levels of Salmonella in tank water and measureable prevalence in feed are possible indicators of aberrantly high levels of Salmonella in a feedlot. Given the ease of collection and processing of these sample types, they may represent good candidates for reliable “predictors” of feedlots that could benefit from pre-harvest interventions targeting Salmonella.