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Associations between Mycobacterium avium subsp. paratuberculosis antibodies in bulk tank milk, season of sampling and protocols for managing infected cows

ScholarsArchive at Oregon State University

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Title Associations between Mycobacterium avium subsp. paratuberculosis antibodies in bulk tank milk, season of sampling and protocols for managing infected cows
Names Cazer, Casey L. (creator)
Mitchell, Rebecca M. (creator)
Cicconi-Hogan, Kellie M. (creator)
Gamroth, Michael (creator)
Richert, Roxann M. (creator)
Ruegg, Pamela L. (creator)
Schukken, Ynte H. (creator)
Date Issued 2013-11-27 (iso8601)
Note This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by BioMed Central Ltd. The published article can be found at: http://www.biomedcentral.com/bmcvetres.
Abstract BACKGROUND: The objective of this study was to identify associations between the concentration of Mycobacterium
avium subsp. paratuberculosis (MAP) antibodies in bulk milk and potential risk factors in herd management and herd
characteristics, explaining high MAP antibody titers in milk. An extensive questionnaire was administered to 292
organic and conventional dairy farms from New York, Wisconsin and Oregon. Bulk milk samples were taken from each
farm for MAP enzyme-linked immunosorbent assay (ELISA). A general linear model was constructed with MAP ELISA
value as the outcome variable and the management factors and herd characteristics as independent variables, while at the
same time controlling for the study design variables of state, herd size, and production system (organic or conventional).
High bulk tank MAP ELISA value may be due to either a high prevalence of MAP in a herd with many cows contributing
to the antibody titer or due to a few infected cows that produce large quantities of antibodies.
RESULTS: Results of the regression models indicated that bulk milk ELISA value was associated with season of sampling
and the presence or absence of protocols for managing MAP-positive cows. The concentration of MAP antibodies in
bulk milk varied seasonally with a peak in the summer and low concentrations in the winter months. When compared
to farms that had never observed clinical Johne’s disease, keeping MAP-positive cows or only culling them after a
period of delay was associated with an increase in optical density.
CONCLUSIONS: The seasonal variation in MAP antibody titers, with a peak in the summer, may be due to a seasonal
increase in MAP-bacterial load. Additionally, seasonal calving practices may contribute to seasonal fluctuations in MAP
antibody titers in bulk tank milk. Keeping MAP-positive cows increases the antibody titer in bulk milk, likely due to direct
antibody production in the infected cow and indirect triggering of antibody production in herdmates.
Genre Article
Access Condition http://creativecommons.org/licenses/by/3.0/us/
Topic Cattle
Identifier Cazer et al.: Associations between Mycobacterium avium subsp. paratuberculosis antibodies in bulk tank milk, season of sampling and protocols for managing infected cows. BioMed Central Veterinary Research 2013 9:234. doi:10.1186/1746-6148-9-234

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