Detection of Mycobacterium avium subspecies paratuberculosis in naturally exposed dairy heifers and associated risk factors

• Published in: Journal of dairy science Vol. 94; no. 9; pp. 4669 - 4675
• Main Authors: Bolton, M.W., Pillars, R.B., Kaneene, J.B., Mauer, W.A., Grooms, D.L.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.2011; Elsevier
• Subjects: Age Factors; Animal productions; Animals; Biological and medical sciences; blood serum; Cattle; Cattle Diseases - etiology; Cattle Diseases - microbiology; cluster analysis; confidence interval; cows; dairy heifer; dairy heifers; dairy herds; Dairying; enzyme-linked immunosorbent assay; equations; feces; Feces - microbiology; Female; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Johne's disease; MAP fecal shedding; Methods of analysis, processing and quality control, regulation, standards; Michigan; milking; Mycobacterium avium ssp. paratuberculosis (MAP); Mycobacterium avium subsp. paratuberculosis; odds ratio; Paratuberculosis - etiology; Paratuberculosis - microbiology; prospective studies; regression analysis; Risk Factors; Terrestrial animal productions; Vertebrates; Michigan; Mycobacterium avium ssp. paratuberculosis (MAP); MAP fecal shedding; dairy heifer; Johne's disease; Disease; Paratuberculosis; paratuberculosis (MAP); Ox; Mycobacterial infection; Bacteria; Control method; Mycobacterium paratuberculosis; Biological contamination; Ungulata; Bovine; Mycobacterium avium ssp; Mycobacterium avium; Infection; Vertebrata; Mammalia; Analysis method; Mycobacteriales; Risk factor; Dairy industry; Bacteriosis; Mycobacteriaceae; Actinomycetes; Heifer; Artiodactyla; Detection
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2011-4158

An observational prospective study was conducted to identify risk factors associated with fecal shedding of Mycobacterium avium ssp. paratuberculosis (MAP) in naturally exposed dairy heifers. The study population consisted of heifers from 8 dairy herds in Michigan participating in a MAP control demonstration project. Ten heifers from 4 age groups (0 to 3, 4 to 6, 7 to 14, and 15 to 24mo) were selected from each herd every 4mo for 28mo and tested for the presence of MAP by fecal culture (FC). Heifers from dams testing positive for MAP by serum ELISA or FC were preferentially selected, with the remainder of the age cohort filled with randomly selected heifers. Logistic regression using generalized estimating equations to account for clustering of data within herds and repeated measures across heifers was used to evaluate the relationship between MAP FC status of heifers and herd risk factors. In total, 1,842 fecal samples were collected from 1,202 heifers. Thirty-six (2%) fecal samples, representing 27 individual heifers, cultured positive for MAP. Heifers shedding MAP were more likely to occur in herds with adult-cow MAP ELISA prevalence >10% (odds ratio = 4.7; 95% confidence interval: 2.0–11.1) and herds milking >300 cows (odds ratio = 5.7; 95% confidence interval: 2.4–13.4). Mycobacterium avium ssp. paratuberculosis can be cultured from the feces of naturally infected dairy heifers. The future performance of these MAP FC-positive heifers is unknown and needs to be explored.