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  • Author or Editor: Kenneth V. Nordlund x
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Abstract

Objective—To determine whether Salmonella spp could be isolated from the environment of free stall dairies in Wisconsin without any history of clinical salmonellosis and determine the serotype and antimicrobial susceptibility of any Salmonella isolates recovered from the environment.

Design—Cross-sectional study.

Study Population—20 free stall dairies with no history of clinical salmonellosis.

Procedures—Dairy owners completed a questionnaire regarding management and production practices. Multiple swab samples were obtained from throughout the free stall facilities and submitted for bacterial culture for Salmonella spp. Odds ratios were calculated to compare herd-level risk factors between dairies from which Salmonella organisms were isolated and herds from which Salmonella organisms were not isolated.

ResultsSalmonella organisms were isolated from 9 of the 20 (45%) dairies. Salmonella serotype Meleagridis was isolated from 4 dairies, S Meleagridis and S Kentucky were isolated from 2 dairies, S Meleagridis and S Cyprus were isolated from 1 dairy, S Cerro was isolated from 1 dairy, and S Corvallis was isolated from 1 dairy. All isolates were susceptible to all antimicrobial agents tested. None of the potential risk factors analyzed demonstrated a significant association with an increased likelihood of isolating Salmonella spp.

Conclusions and Clinical Relevance—Environmental Salmonella contamination was demonstrated on free stall dairies with no history of clinical salmonellosis. (J Am Vet Med Assoc 2004;225:574–577)

Full access
in Journal of the American Veterinary Medical Association

Objective

To monitor effects that improvements in housing facilities would have on herd performance. Financial measures were calculated to estimate whether improvements resulted in an improved financial status for the farm.

Design

Prospective, observational study.

Animals

160-cow dairy herd.

Procedure

Farm visits were conducted from 1990 to 1994. Areas for improvement were identified, and changes were recommended. Herd production and farm financial records were analyzed before, during, and after adoption of recommended changes.

Results

After improving facilities, somatic cell count was somewhat constant, but tended to decrease during the last 16 months of the study. During the last 8 months of the study, incidence for clinical cases of mastitis decreased to 3.3% per month. Reproductive variables improved dramatically after implementing use of a bull for breeding. Subjective evaluation of cow comfort and lameness indicated apparent improvements in each area. However, milk production remained fairly constant from January 1991 through December 1994.

Review of the farm's financial status revealed that costs of production increased from 1990 through 1993, but decreased in 1994. Slow financial response to improvements were attributed to a large decrease in milk price in 1991 and a poor crop harvest in 1993. Thus, although progress was made toward financial stability, approximately 55% of the farm's assets (determined on a market-basis value) were represented by debt.

Clinical Implications

It is important to monitor financial status when managing complex health problems that involve several aspects of a farm's operation. (J Am Vet Med Assoc 1996;209:1406–1410)

Free access
in Journal of the American Veterinary Medical Association

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