Case-control study: Productivity and longevity of dairy cows that tested positive for infection with Mycobacterium avium ssp. paratuberculosis as heifers compared to age-matched controls

• Published in: Journal of dairy science Vol. 94; no. 6; pp. 2825 - 2831
• Main Authors: Pillars, R.B., Bolton, M.W., Grooms, D.L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2011
• Subjects: Age Factors; Animals; blood serum; Case-Control Studies; case-control study; Cattle; Cattle Diseases - microbiology; Cattle Diseases - physiopathology; Cell Count - veterinary; dairy cow; dairy cows; dairy heifers; dairy protein; Efficiency - physiology; enzyme-linked immunosorbent assay; Enzyme-Linked Immunosorbent Assay - veterinary; Feces - microbiology; Female; herds; Johne's disease; Lactation; longevity; Longevity - physiology; milk; Milk - chemistry; Milk - cytology; Milk - metabolism; milk fat; Mycobacterium avium ssp. paratuberculosis; Mycobacterium avium subsp. paratuberculosis; Mycobacterium avium subsp. paratuberculosis - isolation & purification; Paratuberculosis - microbiology; Paratuberculosis - physiopathology; regression analysis; somatic cell count; Survival Analysis; Mycobacterium avium ssp. paratuberculosis; dairy cow; case-control study; Johne's disease
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2010-3665

A case-control study was performed to determine if dairy heifers testing positive for Mycobacterium avium ssp. paratuberculosis (MAP) before 2 yr of age by either fecal culture or serum ELISA had decreased productivity and longevity as cows compared with age-matched herdmates. Cases were individually matched with 4 controls. Survival analysis was conducted to determine differences in longevity between cases and controls. Conditional logistic regression was used to assess differences in mean 3.5% fat-corrected 305-d mature-equivalent milk, milk fat, and milk protein production, linear somatic cell count, and MAP test and clinical status as mature cows. No significant difference was found between cases and controls for any parameter assessed. Herd production performance and longevity did not appear to be impaired; therefore, testing immature dairy heifers for MAP is not economically justifiable, using currently available culture methods and commercial serum ELISA tests.