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United States Department of Agriculture

Agricultural Research Service

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Research Project: Salmonella in the lymph nodes of cattle: Investigation into the variation in feedlot cattle and differences between fed and dairy cattle

Location: Food and Feed Safety Research

2013 Annual Report


1a.Objectives (from AD-416):
Investigate the potential explanations for the seasonal and regional differences in lymph node prevalence of Salmonella in feedlot cattle and elucidate the factors responsible for the differences observed in lymph node prevalence of Salmonella between fed beef and dairy cattle within the Southwest United States.


1b.Approach (from AD-416):
Seasonal/Regional Feedlot Collections: Using a soil temperature map, we will identify feedlots within 3 or 4 of the ground temperature zones (TX, OK, or KS, and NE) and sample two feedlots/zones during the winter and spring months (Jan, Mar, May). Numerous samples/observations will be collected on each feedlot visit, including: pen fecal pats (4 pens/feedlot; representing 30% of cattle within each pen), hide swabs, feed and water samples, pen soil samples and soil temperature, flies and other insects, fly burden, ambient temperature, humidity, and precipitation. Samples will be cultured for Salmonella and isolates serogrouped. Dairy versus Feedlot Collections: Two feedlots and four dairies (two vaccinated for Salmonella and two non-vaccinated herds), all located within a 100-mile radius in the Southwestern United States, will be utilized in the proposed research. All dairies and feedlots will be sampled monthly (Jan, Mar, May) during the same week. Numerous samples/observations will be collected at each location on each visit including: pen fecal pats (4 pens/operation; representing 30% of cattle within each pen), hide swabs, feed and water samples, pen soil samples and soil temperature, flies and other insects, fly burden, ambient temperature, humidity, and precipitation. Samples will be cultured for Salmonella and isolates serogrouped.


3.Progress Report:

This is a new project, with the goal of increasing our understanding of factors responsible for the high prevalence of Salmonella within the peripheral lymph nodes in feedlot cattle. Project work is also focused on defining differences observed among fed and cull dairy cattle. Fecal and other samples were collected from two dairies and one feedlot, all located within one mile of each other. As work under this project progressed, it became apparent that without collecting lymph nodes from cattle at the different operations to compare to fecal and environmental Salmonella, the data would be speculative at best. For this reason, and although the project was not scheduled to expire until mid FY 2014, the decision was made by project scientists and the cooperator to terminate the project in FY 2013.


Last Modified: 7/31/2014
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