The effect of subclinical Mycobacterium paratuberculosis infection on days open in Michigan, USA, dairy cows
Autor: | James W. Lloyd, John B. Kaneene, D.J Sprecher, Y.J Johnson-Ifearulundu, Joseph C. Gardiner |
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Rok vydání: | 2000 |
Předmět: |
Michigan
media_common.quotation_subject Cattle Diseases Paratuberculosis Enzyme-Linked Immunosorbent Assay Biology Cohort Studies Feces Animal science Food Animals Prevalence medicine Animals Prospective Studies Prospective cohort study Subclinical infection media_common Reproduction medicine.disease Mycobacterium avium subsp. paratuberculosis Dairying Herd Cattle Female Animal Science and Zoology Infertility Female Cohort study |
Zdroj: | Preventive Veterinary Medicine. 46:171-181 |
ISSN: | 0167-5877 |
Popis: | A prospective cohort study design was used to evaluate the impact of subclinical Mycobacterium paratuberculosis infection on days open in a sample of Michigan dairy herds with a history of cows positive for M. paratuberculosis diagnosed by fecal culture. Participating herds were tested and productivity and reproduction records were monitored for 18 months. All cows > or = 24 months old were tested for M. paratuberculosis infection using the ELISA and radiometric fecal-culture (RFC) techniques. Test-negative cows were re-tested at the conclusion of the monitoring period. Multivariable regression models were used. Using both tests in parallel, the overall sample apparent prevalence for M. paratuberculosis infection was 41.8% (223/533 animals tested). Adjusting for diagnostic sensitivity and specificity, this resulted in a calculated sample true prevalence of 59.9%. ELISA-positive cows (on average) had a 28-day increase in days open when compared to ELISA-negative cows (p=0.02). The diagnostic method used to define a case altered the apparent association between paratuberculosis test status and days open. Fecal culture was a less-effective diagnostic tool for use in herds with a high prevalence of infected animals. The increase in days open in the ELISA-positive cows was an indication that perhaps reduced estrus expression or an increased post-partum anestrous period occurred in the subclinically infected ELISA-positive animals. This might have been due to a negative energy balance associated with M. paratuberculosis infection. |
Databáze: | OpenAIRE |
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