Search Results

You are looking at 1 - 2 of 2 items for

  • Author or Editor: Joseph Pelletier x
  • Refine by Access: All Content x
Clear All Modify Search

Objective

To determine associations between subclinical Mycobacterium paratuberculosis infection and milk production, milk components, and somatic cell counts of dairy cattle.

Design

Cross-sectional epidemiologic survey.

Animals

23 dairy herds in Wisconsin containing 1,653 adult cows were studied. The herds had above average milk production and a history of bovine paratuberculosis in the herd within the previous 12 months.

Procedure

All adult cows in the herds were tested for paratuberculosis by use of an absorbed ELISA. Milk yield, fat, protein, and somatic cell count data were retrieved electronically from Dairy Herd Improvement Association records.

Results

147 ELISA-positive and 1,506 ELISA-negative cows were identified. ELISA-positive cows had a mature-equivalent milk production of 376 kg (829 lb)/lactation less than that for ELISA-negative herdmates. Significant difference was not found in lactation average percentages of fat and protein, or somatic cell count linear score. When comparing ELISA-positive and -negative cow's current mature equivalent milk with all previous lactations, significant difference was found only from the immediate-preceding lactation. When this difference was examined by parity group, significant difference was confined to cows in the second lactation.

Clinical Implications

Subclinical paratuberculosis infections, as determined by ELISA, are associated with a 4% reduction in milk yield and add to the already substantial costs of clinical M paratuberculosis infection in the dairy industry. (J Am Vet Med Assoc 1996;208:1872-1876)

Free access
in Journal of the American Veterinary Medical Association

Objective

To use an on-farm recording form to quantify the effect of specific management practices on apparent prevalence of Mycobacterium paratuberculosis in dairy cattle herds.

Design

Epidemiologic survey.

Animals

26 commercial Wisconsin dairy farms.

Procedures

An instrument was developed on the basis of literature review and expert interviews to quantify on-farm management practices associated with increased apparent prevalence of M paratuberculosis. On-farm visits were conducted to assess how specific management practices were conducted. Apparent prevalence of M paratuberculosis infection was measured for all animals > 20 months old on all farms, using a commercial ELISA. Regression analysis was used to identify management variables that were significantly associated with apparent prevalence of M paratuberculosis.

Results

Regression analysis (R 2 = 0.90) identified that high scores for environmental conditions, newborn calf care, grower calf care, bred heifer care, and manure handling were significantly associated with M paratuberculosis apparent prevalence in Wisconsin dairy herds.

Clinical Implications

Environmental conditions, newborn calf care, grower calf management, bred heifer management, and manure handling factors may serve as a prioritized checklist for instructing owners and managers where to place emphasis in changing management practices to limit M paratuberculosis prevalence. Likewise, the factors identified as having low association with apparent prevalence may be de-emphasized in control programs, allowing dairy managers to focus time and finances on more effective components of an M paratuberculosis control program. (J Am Vet Med Assoc 1996;208:1877-1881)

Free access
in Journal of the American Veterinary Medical Association