Biomedical subjects

D R Wolfgang

Publications and source records attributed to D R Wolfgang.

4 recordsLinked to original sources

PubMed2004

Evaluation of IS900-PCR assay for detection of Mycobacterium avium subspecies Paratuberculosis infection in cattle using quarter milk and bulk tank milk samples.

A study was conducted to evaluate sensitivity, specificity, and predictive value of IS900-PCR assay for detection of Mycobacterium avium subspecies paratuberculosis in pooled quarter milk and bulk tank milk. Feces, blood and pooled quarter milk from 1493 lactating cattle on 29 herds were analyzed. Bulk tank milk (n = 29 bulk tanks) samples were also examined. Culture analysis revealed that 10.9%, 2.8%, and 20.6% of fecal, pooled quarter milk samples and bulk tanks were positive for M. avium subsp. paratuberculosis, respectively. While 13.5% and 27.5% of pooled quarter milk samples and bulk tanks were positive by IS900 PCR assay, respectively. Moderate to high antibody titers for M. avium subsp. paratuberculosis were detected in 223 of 1493 (14.4%) cows. Cows positive on fecal culture were taken as true positives relative to which the IS900 PCR assay was evaluated. The sensitivity and predictive value of KELA, pooled quarter milk culture, and IS900 PCR assay increased with lactation age. While the specificity of the tests decreased with increase in lactation age. Overall, the IS900 PCR assay using pooled quarter milk samples had a sensitivity, specificity and predictive value of 0.87, 0.95 and 0.71, respectively. The IS900 PCR assay using bulk tank milk had poor sensitivity (0.21), specificity (0.5) and predictive value (0.6). Pooled quarter milk culture analysis had a very low sensitivity (0.17). The kinetics ELISA had lower sensitivity (0.59), specificity (0.90) and predictive value (0.43) as compared to the IS900 PCR assay using pooled quarter milk samples. Results from our study suggest that IS900 PCR assay using bulk tank milk may not be useful for screening herds with M. avium subsp. paratuberculosis infected animals. In conclusion, use of IS900 PCR assay for cows in 2(nd) lactation and higher, using aseptically collected pooled quarter milk samples, can be a useful tool for screening and monitoring lactating cattle in herds with M. avium subsp. paratuberculosis infection.

Animals↗

PubMed2004

Guidelines for monitoring bulk tank milk somatic cell and bacterial counts.

This study was conducted to establish guidelines for monitoring bulk tank milk somatic cell count and bacterial counts, and to understand the relationship between different bacterial groups that occur in bulk tank milk. One hundred twenty-six dairy farms in 14 counties of Pennsylvania participated, each providing one bulk tank milk sample every 15 d for 2 mo. The 4 bulk tank milk samples from each farm were examined for bulk tank somatic cell count and bacterial counts including standard plate count, preliminary incubation count, laboratory pasteurization count, coagulase-negative staphylococcal count, environmental streptococcal count, coliform count, and gram-negative noncoliform count. The milk samples were also examined for presence of Staphylococcus aureus, Streptococcus agalactiae, and Mycoplasma. The bacterial counts of 4 bulk tank milk samples examined over an 8-wk period were averaged and expressed as mean bacterial count per milliliter. The study revealed that an increase in the frequency of isolation of Staphylococcus aureus and Streptococcus agalactiae was significantly associated with an increased bulk tank somatic cell count. Paired correlation analysis showed that there was low correlation between different bacterial counts. Bulk tank milk with low (<5000 cfu/mL) standard plate count also had a significantly low level of mean bulk tank somatic cell count (<200,000 cells/mL), preliminary incubation count (<10,000 cfu/mL), laboratory pasteurization count (<100 cfu/mL), coagulase-negative staphylococci and environmental streptococcal counts (<500 cfu/mL), and noncoliform count (<200 cfu/mL). Coliform count was less likely to be associated with somatic cell or other bacterial counts. Herd size and farm management practices had considerable influence on somatic cell and bacterial counts in bulk tank milk. Dairy herds that used automatic milking detachers, sand as bedding material, dip cups for teat dipping instead of spraying, and practiced pre-and postdipping had significantly lower bulk tank somatic cell and/or bacterial counts. In conclusion, categorized bulk tank somatic cell and bacterial counts could serve as indicators and facilitate monitoring of herd udder health and milk quality.

Animals↗

PubMed2000

A computerized mastitis decision aid using farm-based records: an artificial neural network approach.

A computer module was developed and tested that used field survey and Dairy Herd Improvement Association (DHIA) data to broadly classify bacterial causes of mastitis in dairy herds. Further development of the computer model could aid interpretation of DHIA data by dairy record processing centers and herd consultants. This diagnostic module was developed with an artificial neural network, a technology that processes complex data in a manner similar to human brain function. Information describing herd management practices, quarter milk samples, and monthly DHIA data was collected from Pennsylvania dairy herds with moderate to high somatic cell counts. This information was used to develop or train an artificial neural network model that discriminated among four categories of bacterial organisms (contagious, environmental, no significant growth, and other) associated with clinical and subclinical mastitis. After training the model, new DHIA and management data were presented to the model to assess its ability to classify bacteriological etiology. When the artificial neural network was used, the probabilities of diagnosing the bacteriologic status from three randomly selected cow groups and from new untested herds ranged from 57 to 71%. Performance of the artificial neural network model was best in herds with higher frequency of minor and contagious pathogens. Prediction results for the same test data with linear discriminant analysis were less successful, ranging from 42 to 57%.

Animals↗

PubMed2000

Characteristics of veal calves upon arrival, at 28 and 84 days, and at end of the production cycle.

Holstein bull calves arriving at five special-fed veal farms (eight production groups) were scored for various physical condition traits and blood-sampled within 2 h after arrival and at 28 d, 84 d, and 1 wk prior to slaughter at 116 to 143 d. Of 1179 total calves in the production groups, 758 calves were scored and evaluated. Blood cell analyses (red and white blood cell counts, hemoglobin, and packed cell volume) were conducted at all four sampling times; total serum protein concentration was obtained at 0 and 28 d. The study was initiated in autumn and ended the following autumn. Mean initial and final body weights were 46.3+/-0.17 and 209.7+/-0.77 kg; mean mortality was 2.5%. Average daily gain of the eight groups ranged from 1.23 to 1.70 kg/d. Subjective scores of 5 = excellent to 1 = very poor condition were used to evaluate 16 different physical condition characteristics. With the exception of leg joint, hoof, and foot scores, most of the physical condition scores exhibited improvement during the first 28 d. Foot and leg impairments did not appear to hinder the ambulatory ability of the calves during the production period. Physical condition scores at d 0 and 28 were generally not related to numbers or types of medical treatments (enteric, respiratory, other, or total) or to average daily gain during the production period. Means for most erythrocytic and leukocytic traits upon arrival (d 0) were within normal ranges, although 27.4% of the calves were clinically or marginally anemic. Final mean hemoglobin and packed cell volume were 8.53 g/dl and 26.1%. Forty-three percent of the calves at d 0 were colostral deficient, assuming that total serum protein concentrations of <5.5 g/dl indicate colostral deficiency. No blood trait was consistently correlated with body weight gain when gain during the production period was divided into quartiles and the blood traits were averaged by gain quartile. Calves in the lowest serum total protein quartile (mean 4.58 g/dl) had more respiratory and total medical treatments than quartiles with higher total protein means. Dairy bull calves arriving at veal production units after transporting from the dairy farm to the auction market (or other collection facility) have several physical impairments. However, most of these physical impairments are improved early in the veal feeding period and are not generally related to subsequent growth rate or medical treatment.

Aging↗