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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #317543
Title: The effects of progressing and nonprogressing Mycobacterium avium ssp. paratuberculosis infection on milk production in dairy cows

Author
item SMITH, R - University Of Illinois
item GROHN, Y - Cornell University
item PRADHAN, A - University Of Maryland
item WHITLOCK, R - University Of Pennsylvania
item Van Kessel, Jo Ann
item SMITH, J - University Of Vermont
item WOLFGANG, D - Pennsylvania State University
item SCHUKKEN, Y - Cornell University

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2015
Publication Date: 2/1/2016
Citation: Smith, R.L., Grohn, Y.T., Pradhan, A.K., Whitlock, R.W., Van Kessel, J.S., Smith, J.M., Wolfgang, D.R., Schukken, Y.H. 2016. The effects of progressing and nonprogressing Mycobacterium avium ssp. paratuberculosis infection on milk production in dairy cows. Journal of Dairy Science. 99:1383-1390.

Interpretive Summary: Johne’s disease (JD) is a chronic enteric disease of cattle and other ruminants caused by an infection with Mycobacterium avium subsp. paratuberculosis (MAP). It is estimated that at least two thirds of US dairy herds have at least one cow that is infected with MAP. The cost of JD to US dairy producers was estimated to be more than $200 million per year. This disease is difficult to study in herds because the infection is very slow to progress, many infected animals never show clinical signs, are only detected a few years after initial infection, or are actually never detected. In this study, analysis of milk production and MAP test data from three commercial dairy herds found that both current disease status and eventual disease status affected milk production. Animals that developed high-positive disease had large and continuous decreases in milk production as disease status progressed. Test-positive animals that did not develop high-positive disease suffered an initial decrease in milk production, but recovered over time. Economic analysis of Johne’s control will be greatly impacted by these results. This information will be helpful to other scientists and to the dairy industry.

Technical Abstract: Longitudinal data from three commercial dairy herds in the northeast United States, collected from 2004 to 2011, were analyzed to determine the effect of Johne’s disease status and path on milk production. Disease status, as indicated by Mycobacterium avium subsp. paratuberculosis test results, was determined through quarterly ELISA serum testing, biannual fecal culture, and culture of tissues and feces at slaughter. Milk production data were collected from the Dairy Herd Improvement Association. Animals with positive test results were categorized as high path (at least one high-positive culture) and low path. The effect of Johne’s disease path and status on milk production were analyzed using a mixed linear model with an autocorrelation random effect structure. Low and high path animals produced more milk prior to their first positive test than always-negative animals, especially high path animals. While mean production decreased after a first positive test, low path animals were predicted to recover some productivity. High path animals continued to exhibit a decrease in milk production, especially after their first high-positive fecal culture. These results show that not all animals that test positive for Johne’s disease will have long-term production losses.