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Title: The relationship between Salmonella detection from milk filters and bulk milk and the fecal shedding prevalence of Salmonella in a dairy herd

Author
item Van Kessel, Jo Ann
item Karns, Jeffrey
item WOLFGANG, D - PENN STATE UNIVERSITY
item HOVINGH, E - PENN STATE UNIVERSITY
item SCHUKKEN, Y - CORNELL UNIVERSITY

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2007
Publication Date: 7/9/2007
Citation: Van Kessel, J.S., Karns, J.S., Wolfgang, D.R., Hovingh, E., Schukken, Y. 2007. The relationship between Salmonella detection from milk filters and bulk milk and the fecal shedding prevalence of Salmonella in a dairy herd. Joint Meeting of the ADSA, AMSA, ASAS and PSA, July 7-12, 2007, San Antonio, Texas.

Interpretive Summary:

Technical Abstract: Although dairy cattle are known reservoirs for salmonellae, cattle that are shedding this organism are often asymptomatic and difficult to identify. A dairy herd that was experiencing an outbreak of Salmonella enterica subsp. enterica Cerro was monitored for two years. Fecal samples from the lactating cows were collected every six to eight weeks and tested for the presence of Salmonella using traditional culture methods. Fecal shedding of Salmonella fluctuated throughout the observation period and prevalence ranged from 8% to 88%. During this sampling period, bulk milk and milk filters were cultured for the presence of Salmonella on a weekly basis. Salmonella was detected in 15% of milk samples (n = 109) and in 78% (n = 107) of the milk filters. Results of weekly bulk milk quality testing (i.e. bulk tank somatic cell score, standard plate count, preliminary incubation count) were typically well within acceptable ranges. When observed over time, the recovery of Salmonella from the milk filter, and to a lesser extent from the bulk milk, closely paralleled fecal prevalence of Salmonella in the herd. Analysis of in-line milk filters has been used previously as a useful way to detect the presence of zoonotic bacteria entering the bulk tank. Based on results of this study, milk filter analysis may also be a convenient method for monitoring shedding prevalence at the herd level. Bulk milk samples would eventually detect high prevalence farms but individual bulk milk samples have low sensitivity.