Title Evaluation of fecal culture pooling methods for detection of Mycobacterium avium subspecies paratuberculosis in a beef herd
Author(s) Jensen SM1,2, Lombard JE1,2, Garry FB1.
Institution(s) 1Integrated Livestock Management, Colorado State University, Fort Collins, CO, USA; 2USDA:APHIS:VS;Centers for Epidemiology and Animal Health, Fort Collins, CO, USA
Source Eighth International Colloquium on Paratuberculosis
Section 5: Diagnosis
Presentation Poster
Abstract
Given the increased cost of whole herd fecal culture for the detection of Mycobacterium avium subspecies paratuberculosis (MAP) infection, studies evaluating fecal pooling in dairy cattle have been conducted. This beef cattle study evaluated individual fecal samples, strategically pooled samples, and collection order pooled samples in detecting infected animals. Individual fecal samples were collected from 174 beef cattle and subsequently divided into three aliquots for individual animal testing, strategic pooling and ordered pooling. Each sample pool included 4-5 individual samples and all testing was performed concurrently. Individuals were selected for a strategic pool based on their ranked age whereas order pooled samples were based on order of collection. Nineteen of the 174 individual samples, 6 of the 35 strategic pools, and 2 of the 35 ordered pools were culture positive. Four of the six strategic pools and one of the two ordered pools that were culture positive contained at least one of the 19 individual samples found to be culture positive. Both individuals classified as heavy shedders were detected by strategic pooling, while only one heavy shedder was detected by ordered pooling. Of the positive pools, two strategic pools and one ordered pool contained no samples found to be positive upon individual culture. One sample within each pooling method was found to contain two culture positive individuals. The results of this preliminary beef study suggest that bacteriologic culture of strategically pooled samples may provide a more reliable method for detection of MAP infected animals as compared to ordered pooling. However, pooling of samples from beef herds where the majority of infected animals are moderate to low shedders may not be a sensitive enough method because it significantly reduces the ability to detect MAP infection compared to individual fecal culture.

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