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1.
OBJECTIVE: To develop partial budgets of the economic costs of 2 test strategies for screening cattle for persistent infection with bovine viral diarrhea virus (BVDV). DESIGN: Partial budget analysis. ANIMALS: 938 calves arriving at 2 stocker operations. PROCEDURE: Calves were tested to determine prevalence of persistent BVDV infection. Test strategies that were evaluated included a single-test strategy consisting of immunohistochemical staining of skin biopsy specimens from all animals and a 2-test strategy consisting of polymerase chain reaction (PCR) assaying of pooled blood samples followed by immunohistochemical staining of skin biopsy specimens from animals in pools for which assay results were positive. Break-even costs (i.e., cost of persistent BVDV infection per animal necessary to justify whole-herd diagnostic testing) associated with each test strategy were calculated as a function of disease prevalence and test cost. RESULTS: Apparent prevalence of persistent BVDV infection was 0.32%. Sensitivity and specificity of the PCR assay for pooled samples were 100% and 89.7%, respectively. Regardless of the prevalence of persistent BVDV infection, the break-even cost for the 2-test strategy was lower than the break-even cost for the single-test strategy. However, the economic advantage was greatest when prevalence was low. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that using a 2-test strategy to screen cattle for persistent BVDV infection, whereby the first test involves PCR assaying of pooled samples and the second involves immunohistochemical testing only of those animals represented in pooled samples with positive assay results, will reduce the cost of screening incoming feedlot cattle, compared with immunohistochemical testing of all animals.  相似文献   

2.
A stochastic spreadsheet model was developed to obtain estimates of the costs of whole herd testing on dairy farms for Mycobacterium avium subsp. paratuberculosis (Map) with pooled fecal samples. The optimal pool size was investigated for 2 scenarios, prevalence (a low-prevalence herd [< or = 5%] and a high-prevalence herd [> 5%]) and for different herd sizes (100-, 250-, 500- and 1,000-cow herds). All adult animals in the herd were sampled, and the samples of the individuals were divided into equal sized pools. When a pool tested positive, the manure samples of the animals in the pool were tested individually. The individual samples from a negative pool were assumed negative and not tested individually. Distributions were used to model the uncertainty about the sensitivity of the fecal culture at farm level and Map prevalence. The model randomly allocated a disease status to the cows (not shedding, low Map shedder, moderate Map shedder, and heavy Map shedder) on the basis of the expected prevalence in the herd. Pooling was not efficient in 100-cow and 250-cow herds with low prevalence because the probability to detect a map infection in these herds became poor (53% and 88%) when samples were pooled. When samples were pooled in larger herds, the probability to detect at least 1 (moderate to heavy) shedder was > 90%. The cost reduction as a result of pooling varied from 43% in a 100-cow herd with a high prevalence to 71% in a 1,000-cow herd with a low prevalence. The optimal pool size increased with increasing herd size and varied from 3 for a 500-cow herd with a low prevalence to 5 for a 1,000-cow herd with a high prevalence.  相似文献   

3.
Does control of bovine viral diarrhoea infection make economic sense?   总被引：3，自引：0，他引：3  
AIM: To provide an economic analysis of the costs of control or eradication of bovine viral diarrhoea (BVD) against the estimated costs of the disease. METHODS: A decision-tree approach was adapted to an analysis of the costs of bovine viral diarrhoea virus (BVDV) infection and that of three main control options (vaccination, test-and-cull, and increased biosecurity) and their combinations, to the dairy industry in New Zealand. The model was based on an average herd of 322 milking cows. Endemic, epidemic and sporadic effects of BVDV infection were modelled in the herd, to derive an estimate of costs. RESULTS: The cost of BVDV infection to an infected average-sized dairy herd in New Zealand was estimated to be NZ $11,334 (or NZ $35.19 per cow) per annum, and NZ $48,311 over 10 years. Based on these calculations, the estimate of the annual cost of BVDV infection to the dairy industry in New Zealand was in excess of NZ $23 million per annum. While all of the control options required financial input, the rate of return compared with the cost of BVD, when viewed over a 10-year term, was as high as 123%. CONCLUSIONS: All control options offered considerable savings compared with the cost of BVD infection, and control is economically favourable. Uncertainty over the likely efficacy of the control options under field conditions in New Zealand would not allow a firm choice of one option over another at this stage, and more work on determining the efficacy of those control options in New Zealand is needed.  相似文献   

4.
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5.
OBJECTIVE: To evaluate sensitivity of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis (MAP) in large dairy herds and assess the use of the method for estimation of MAP prevalence. ANIMALS: 1,740 lactating cows from 29 dairy herds in California. PROCEDURE: Serum from each cow was tested by use of a commercial ELISA kit. Individual fecal samples were cultured and used to create pooled fecal samples (10 randomly selected fecal samples/pool; 6 pooled samples/herd). Sensitivity of MAP detection was compared between Herrold's egg yolk (HEY) agar and a new liquid culture method. Bayesian methods were used to estimate true prevalence of MAP-infected cows and herd sensitivity. RESULTS: Estimated sensitivity for pooled fecal samples among all herds was 0.69 (25 culture-positive pools/36 pools that were MAP positive). Sensitivity increased as the number of culture-positive samples in a pool increased. The HEY agar method detected more infected cows than the liquid culture method but had lower sensitivity for pooled fecal samples. Prevalence of MAP-infected cows was estimated to be 4% (95% probability interval, 2% to 6%) on the basis of culture of pooled fecal samples. Herd-level sensitivity estimate ranged from 90% to 100% and was dependent on prevalence in the population and the sensitivity for culture of pooled fecal samples. CONCLUSIONS AND CLINICAL RELEVANCE: Use of pooled fecal samples from 10 cows was a cost-effective tool for herd screening and may provide a good estimate of the percentage of MAP-infected cows in dairy herds with a low prevalence of MAP.  相似文献   

6.
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7.

Background

Bovine viral diarrhoea (BVD) is an infectious disease of cattle with a worldwide distribution. Herd-level prevalence varies among European Union (EU) member states, and prevalence information facilitates decision-making and monitoring of progress in control and eradication programmes. The primary objective of the present study was to address significant knowledge gaps regarding herd BVD seroprevalence (based on pooled sera) and control on Irish farms, including vaccine usage.

Methods

Preliminary validation of an indirect BVD antibody ELISA test (Svanova, Biotech AB, Uppsala, Sweden) using pooled sera was a novel and important aspect of the present study. Serum pools were constructed from serum samples of known seropositivity and pools were analysed using the same test in laboratory replicates. The output from this indirect ELISA was expressed as a percentage positivity (PP) value. Results were used to guide selection of a proposed cut-off (PCO) PP. This indirect ELISA was applied to randomly constructed within-herd serum pools, in a cross-sectional study of a stratified random sample of 1,171 Irish dairy and beef cow herds in 2009, for which vaccination status was determined by telephone survey. The herd-level prevalence of BVD in Ireland (percentage positive herds) was estimated in non-vaccinating herds, where herds were classified positive when herd pool result exceeded PCO PP. Vaccinated herds were excluded because of the potential impact of vaccination on herd classification status. Comparison of herd-level classification was conducted in a subset of 111 non-vaccinating dairy herds using the same ELISA on bulk milk tank (BMT) samples. Associations between possible risk factors (herd size (quartiles)) and herd-level prevalence were determined using chi-squared analysis.

Results

Receiver Operating Characteristics Analysis of replicate results in the preliminary validation study yielded an optimal cut-off PP (Proposed Cut-off percentage positivity - PCO PP) of 7.58%. This PCO PP gave a relative sensitivity (Se) and specificity (Sp) of 98.57% and 100% respectively, relative to the use of the ELISA on individual sera, and was chosen as the optimal cut-off since it resulted in maximization of the prevalence independent Youden’s Index.The herd-level BVD prevalence in non-vaccinating herds was 98.7% (95% CI - 98.3-99.5%) in the cross-sectional study with no significant difference between dairy and beef herds (98.3% vs 98.8%, respectively, p = 0.595).An agreement of 95.4% was found on Kappa analysis of herd serological classification when bulk milk and serum pool results were compared in non-vaccinating herds. 19.2 percent of farmers used BVDV vaccine; 81% of vaccinated herds were dairy. A significant association was found between seroprevalence (quartiles) and herd size (quartiles) (p < 0.01), though no association was found between herd size (quartiles) and herd-level classification based on PCO (p = 0.548).

Conclusions

The results from this study indicate that the true herd-level seroprevalence to Bovine Virus Diarrhoea (BVD) virus in Ireland is approaching 100%. The results of the present study will assist with national policy development, particularly with respect to the national BVD eradication programme which commenced recently.  相似文献   

8.
The purpose of this study was to survey the seroprevalence of infection with the agents of production-limiting diseases in dairy cattle in New Brunswick, Nova Scotia, and Prince Edward Island. In 30 randomly selected herds per province, 30 cattle per herd were randomly selected and tested for antibodies to bovine leukemia virus (BLV) and Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis), while 5 unvaccinated cattle over 6 months of age were tested for antibodies to bovine viral diarrhea virus (BVDV). For BLV, 20.8% (15.8% to 27.0%) of cows were positive, and 70.0% (60.3% to 79.7%) of herds had at least one positive cow. In BLV-positive herds, the average BLV prevalence was 30.9% (24.8% to 37.2%). For M. paratuberculosis, 2.6% (1.8% to 3.9%) of cows were positive, and 16.7% (8.8% to 24.5%) of herds had at least 2 M. paratuberculosis-positive cows. In M. paratuberculosis-positive herds, the average M. paratuberculosis prevalence was 8.5% (6.9% to 10.1%). For BVDV, 46.1% (35.5% to 56.7%) of herds had at least 1 BVDV-positive animal with a titer greater than or equal to 1:64.  相似文献   

9.
We used a linear programming model to estimate the financial returns to a Staphylococcus aureus testing and control program over a 1-year period for a 100-cow herd, with a 8636-kg rolling-herd average. Six tests, which vary in sensitivity from 0.80 to 0.98 and specificity of 0.99, were examined in simulated herds with 10, 20 and 30% prevalence of S. aureus infection. Sensitivity of these results to a range of assumptions regarding rolling-herd average, milk price, somatic cell-count premium, and cost and cure rate of dry treatment were examined to determine the profits from the program. The profits of a control program are most dependent upon prevalence, cell-count premium, and cost of dry treatment. In our simulation for a 100-cow herd, a testing and control program appears to cost less than US$10 per cow per year, and pays for itself within 1 yr, except under the lowest prevalence and most-adverse conditions (low yield, high cost of dry treatment, or low SCC premium).  相似文献   

10.
A stochastic simulation model was developed to assess the risk of introduction of Mycobacterium avium subsp. paratuberculosis infection into a dairy herd through purchase of female replacement cattle. The effects of infection prevalence in the source herd(s), number of females purchased, and testing by enzyme-linked immunosorbent assay (ELISA) alone or ELISA and fecal culture as risk mitigation strategies were evaluated. Decisions about negative test results were made on a lot and individual basis. A hypothetical dairy herd, free from M. a. paratuberculosis, which replaced 1 lot (10, 30, or 100) of cows per year, was considered. Probability distributions were specified for the sensitivities and specificities of ELISA and fecal culture, the proportion of infected herds and within-herd prevalence for randomly selected replacement source herds (high prevalence) and herds in level 2 (medium prevalence) and level 3 (low prevalence) of the Voluntary Johne's Disease Herd Status Program (VJDHSP). Simulation results predicted that 1-56% of the lots had at least 1 M. a. paratuberculosis-infected cow. Assuming that ELISA sensitivity was 25%, simulation results showed on a lot basis that between 0.4% and 18% and between 0.1% and 9% were predicted to have at least 1 infected cow not detected by ELISA and by a combination of ELISA and fecal culture, respectively. On an individual cow basis, between 0.1% and 8.3% of ELISA-negative cattle in ELISA-positive lots were estimated to be infected. In both the lot and individual analyses, the probability of nondetection increased with larger lot sizes and greater prevalence. Sensitivity analysis indicated that the effect of a lower ELISA sensitivity (10%) was a variable decrease in mean detection probabilities for all combinations of prevalence and lot size. The benefit of testing introduced cattle with ELISA alone or in combination with fecal culture was found to be minimal if cows were purchased from known, low-prevalence (level 3) herds. The value of testing by ELISA alone or in combination with fecal culture was greatest in high-prevalence herds for all lot sizes. Testing of random-source cattle, bought as herd replacements, can partially mitigate the risk of introduction of M. a. paratuberculosis but not as well as by using low-prevalence source herds (level-3 VJDHSP), with or without testing.  相似文献   

11.
OBJECTIVE: To determine the association between the existence of a calf persistently infected (PI) with bovine viral diarrhea virus (BVDV) and pen morbidity. ANIMALS: 5,041 calves in 50 pens at a feedlot in Iowa. PROCEDURE: In a longitudinal study, ear notches were collected from cattle and tested for BVDV antigen. Characteristics of each pen (owner, sex, disease rate, number of groups, and source) were recorded. The association between the existence of a BVDV-PI calf and morbidity in each pen was examined. RESULTS: Commingling was associated with an increase in respiratory tract disease (odds ratio [OR], 3; 95% confidence interval [CI], 2.5 to 3.6). Ten BVDV-PI calves (10/5,041 [0.2%]) were identified in 8 of 50 pens. A BVDV-PI calf was associated with reduced pen-level respiratory tract disease (OR, 0.7; 95% CI, 0.5 to 0.9). Disease prevalence (mean +/- SD morbidity, 7.9 +/- 3.1%) was lowest in pens containing single-source cattle and a BVDV-PI calf (4 pens containing 302 cattle), compared with single-source cattle with no BVDV-PI calf (mean morbidity, 11.89 +/- 9.7%; 31 pens containing 3,093 cattle), commingled cattle with no BVDV-PI calf (mean morbidity, 29.3 +/- 16.22%; 11 pens containing 1,127 cattle), and commingled cattle with a BVDV-PI calf (mean morbidity, 28.6 +/- 10.1%; 4 pens containing 519 cattle). CONCLUSIONS AND CLINICAL RELEVANCE: Commingling was the greatest risk factor associated with morbidity in each pen. A BVDV-PI calf in a pen was not associated with increased disease prevalence in commingled groups.  相似文献   

12.
In 1992, significant calf losses occurred between birth and weaning in a 650-cow Saskatchewan beef herd. These losses occurred subsequent to ill-thrift and disease, and every calf necropsied was found to be persistently infected with bovine viral diarrhea virus (BVDV). The objectives of this study were to describe the losses associated with fetal infection with BVDV in this herd and to determine why they occurred. For investigative purposes, blood samples were collected from the entire cow herd and the surviving calves at pregnancy testing in 1992, and tested by virus isolation for BVDV. Between 51 and 71 persistently infected calves were born in 1992. Bovine viral diarrhea virus was only isolated from calves. The only confirmed fetal infections with BVDV were recorded as the birth of persistently infected calves. However, abortions, reduced pregnancy rates, and delayed calvings were also recorded in the cow herd and may have been the result of fetal infections. The herd was monitored again in 1993. Fetal infections with BVDV were recorded as the birth of stunted, deformed, and persistently infected calves. The greatest losses due to fetal infection with BVDV in the 2 years of this study occurred in cows that were 3-years-old at calving (second calves). Bovine viral diarrhea virus appears to have remained endemic in this herd by transmission from persistently infected calves on young 3- and 4-year-old cows to naive calved 2-year-old cows that were mingled with them annually for rebreeding. Significant numbers of the 2-year-old cows remained naive to BVDV, because they were segregated from persistently infected calves at weaning, preventing cross-infection with BVDV.  相似文献   

13.
Samples from livestock or food items are often submitted to microbiological analysis to determine whether or not the group (herd, flock or consignment) is shedding or is contaminated with a bacterial pathogen. This process is known as 'herd testing' and has traditionally involved subjecting each sample to a test on an individual basis. Alternatively one or more pools can be formed by combining and mixing samples from individuals (animals or items) and then each pool is subjected to a test for the pathogen. I constructed a model to simulate herd-level sensitivity of the individual-sample approach (HSe) and the herd-level sensitivity of the pooled-sample approach (HPSe) of tests for detecting pathogen. The two approaches are compared by calculating the relative sensitivity (RelHSe = HPSe/HSe). An assumption is that microbiological procedures had 100% specificity. The new model accounts for the potential for HPSe and RelHSe to be reduced by the dilution of pathogen that occurs when contaminated samples are blended with pathogen-free samples. Key inputs include a probability distribution describing the concentration of the pathogen of interest in samples, characteristics of the pooled-test protocol, and a 'test-dose-response curve' that quantifies the relationship between concentration of pathogen in the pool and the probability of detecting the target organism. The model also compares the per-herd cost of the pooled-sample and individual-sample approaches to herd testing. When applied to the example of Salmonella spp. in cattle feces it was shown that a reduction in the assumed prevalence of shedding can cause a substantial fall in HPSe and RelHSe. However, these outputs are much less sensitive to changes in prevalence when the number of samples per pool is high, or when the number of pools per herd-test is high, or both. By manipulating the number of pools per herd and the number of samples per pool HPSe can be optimized to suit the range of values of true prevalence of shedding of Salmonella that are likely to be encountered in the field.  相似文献   

14.
We used a linear programming model to estimate the financial returns to a Staphylococcus aureus testing and control program over a 1-year period for a 100-cow herd, with a 8636kg rolling-herd average. Six tests, which vary in sensitivity from 0.80 to 0.98 and specificity of 0.99, were examined in simulated herds with 10, 20, and 30% prevalence of S. aureus infection. Sensitivity of these results to a range of assumptions regarding rolling-herd average, milk price, somatic cell-count premium, and cost and cure rate of dry treatment were examined to determine the profits from the program. The profits of a control program are most dependent upon prevalence and cell-count premium. In our simulation for a 100-cow herd, a testing and control program results in a profit ranging from US$1.50 to US$20 per cow per year, except under the lowest prevalence and most-adverse conditions (low yield or low SCC premium).  相似文献   

15.
Dutch dairy herds closed for at least 3 years with no history of paratuberculosis were recruited for a study on herd-certification. One hundred dairy herds were tested for Mycobacterium paratuberculosis at 6-month intervals by pooled faecal culture (five individual animal samples per pool) with solid media. Ninety of the herds completed 9 herd tests and 10 herds dropped out of the study for reasons other than a paratuberculosis diagnosis. Of the 90 herds completing the full study, 61% eventually were found to be M. paratuberculosis-infected. The number of infected herds detected decreased with each round of testing. Assuming that all infected herds had been detected by the ninth herd test, the observed percentage of herds that were truly noninfected (P-free) after each round of testing was calculated. The observed P-free was compared to the predicted P-free based on a previously reported herd-certification model. The P-free predicted by the model was significantly different from the observed P-free. When a single assumption in the model was changed and a diagnostic sensitivity of 40–50% was selected, the predicted P-free closely approximated the observed P-free for the 90 Dutch dairy herds studied. The critical assumption that was changed for Version 2.0 of the model was within-herd infection prevalence for infected but test-negative herds after each round of serial testing. Model Version 1.0 had assumed a 50% decrease in within-herd prevalence but Version 2.0 assumed a stable within-herd prevalence. Culture of pooled faecal samples provides a high-sensitive, high-specific, low-cost test for herd-certification programs.  相似文献   

16.
Mashhad is a major dairy production in Iran. The subject of this study was to survey the seroprevalence of Bovine Viral Diarrhea Virus (BVDV) infection using an indirect Enzyme-linked immunosorbent assay (ELISA) test in industrial dairy cattle herds in suburb of Mashhad-Iran. Totally, 141 serum samples were tested. None of the herds had been vaccinated against BVDV. Commercial indirect ELISA kit was used. The herds divided to 3 sizes as cow population. They were included: small, medium and large herds. Data were analyzed using Chi-square test. Ninety-seven (68.79%) cows were ELISA seropositive. However, the true BVDV seroprevalence was 72.25%. All of the herds were antibody positive against BVDV. The prevalence ranged from 66 to 100% within the herds. There were no significant differences between the presence of antibodies to BVDV and the herd size (P > 0.05). The prevalence in animals lower than 2 years old differed significantly with cows higher than 2 years old (P < 0.05). According to the results, it is concluded that it is likely the presence of persistently infection (PI) animal(s) within the herds in suburb of Mashhad-Iran, which is responsible for the presence antibody.  相似文献   

17.
AIMS: To assess the sensitivity and specificity of a bulk tank milk (BTM) antibody enzyme-linked immunosorbent assay (ELISA) to detect likely infection of a dairy herd with bovine viral diarrhoea virus (BVDV). The ELISA was subsequently used to estimate the prevalence of likely infected herds in parts of the North Island of New Zealand. METHODS: BTM samples from 724 randomly selected dairy herds in the Waikato, Bay of Plenty and Northland regions of New Zealand were tested for BVDV antibodies. From this group, 20 herds were again randomly selected from each of the quartiles of the ELISA percentage inhibition (%INH) result. From each participant herd, serum from 15 randomly selected calves aged 6-18 months and 15 cows was collected and tested using an indirect blocking ELISA for BVDV antibodies. RESULTS: Among serum results from calves from 50 herds available for analysis, 34 (68%) herds were classified as likely non-infected (0-3 seropositive among 15 calves) and 16 (32%) as likely infected (5-15 seropositive among 15 calves). Receiver-operator characteristic (ROC) analysis identified an optimal cut-off for BTM of 80%INH associated with 81% sensitivity and 91% specificity for likely herd infection. The prevalence of BVDV antibodies in cows within herds and %INH for BVDV in bulk milk were positively correlated (p<0.01). The association between bulk milk %INH and the prevalence of BVDV antibodies in calves was stronger than the same association in cows. Based on the threshold of 80%INH, the 95% confidence interval (CI) for prevalence of likely infection in the 724 herds in the Waikato, Bay of Plenty and Northland regions of New Zealand was 12-17%. Vaccination against BVDV was not significantly associated with the likely infection status of the herd based on prevalence of BVDV antibodies among calves. CONCLUSION: An ELISA test result for BVDV antibodies in BTM >/=80%INH can be used as a threshold to indicate the presence of likely infection with BVDV in dairy herds in New Zealand, with 81% sensitivity and 91% specificity.  相似文献   

18.
A spreadsheet program was written to perform decision tree analysis for control of paratuberculosis (Johne's disease), when testing all adults in a herd and culling all animals with positive test results. The program incorporated diagnostic test sensitivity, specificity, and test cost with the cost or value of each of the 4 possible outcomes; true-positive, true-negative, false-positive, and false-negative test results. The program was designed to repeat the analysis for the independent variable pretest paratuberculosis prevalence (0 to 100%). Model output was graphed as profit or loss in dollars vs pretest prevalence. The threshold was defined as the pretest prevalence at which benefit-cost equaled zero. Reed-Frost disease modeling techniques were used to predict the number of Mycobacterium paratuberculosis-infected replacement heifers resulting from infected cows during a control program. Sensitivity analysis was performed on variables of the decision tree model; test sensitivity, specificity, test cost, and factors affecting the cost of paratuberculosis to a commercial dairy. A test and cull program was profitable when paratuberculosis caused greater than or equal to 6% decrease in milk production if the pretest prevalence was greater than 6%, test sensitivity was 50%, test specificity was 98%, and the testing cost was $4/cow. Test specificities greater than 98% did not markedly affect the threshold for tests with a 50% sensitivity and costing $4/cow. Test sensitivity had minimal effect on the threshold. Using a diagnostic test with a 50% sensitivity and a 98% specificity as an example, test cost was shown to affect the threshold prevalence at which the test and cull program became profitable.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Fecal samples from 733 cows in 11 dairy herds with a low prevalence of paratuberculosis were cultured for the presence of Mycobacterium avium subsp. paratuberculosis both individually and after combining (pooling) in groups of 5. The culture procedure was the modified Jorgensen method, which uses NaOH and oxalic acid for decontamination and modified Lowenstein-Jensen agar slants for cultivation. Pooling was performed by mixing fecal samples from 5 animals ordered by age, herein referred to as strategic pooling. Culture of individual fecal samples detected M. a. paratuberculosis infections in 43 of the 733 cows and 7 of 11 infected herds (herd sensitivity = 64%). Culture of pooled fecal samples detected M. a. paratuberculosis in 28 of 151 pooled samples representing 8 of the infected 11 herds (herd sensitivity = 73%). Feces of the 43 culture-positive cows was included in 32 pools: of these 32 pools, 26 were culture positive and 6 were culture negative. In addition to the 26 positive pools containing feces from cows that were found culture positive on individual fecal samples, another 2 pools were culture positive, although comprised of feces from cows with negative results after culture of individual fecal samples. From the total of 45 infected cows that were found (43 by individual fecal culture and an additional 2 by pooled fecal culture), individual fecal culture detected 43 of these 45 (96%), while pooled fecal culture detected 39 (87%). Culture of strategically pooled fecal samples using the modified Jorgensen method was equivalent in herd sensitivity to the culture of individual fecal samples and is significantly less expensive.  相似文献   

20.
Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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