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Economic impact of reduced milk production associated with Johne's disease on dairy operations in the USA.
Accurately assessing the economic impacts of diseases and other factors that affect milk production requires that the demand for milk be taken into account. Because demand for milk in the USA is relatively inelastic (i.e., consumers generally purchase a somewhat fixed amount over a given time frame, regardless of fluctuations in price), consumers tend to reap much of the benefit of enhanced production. An examination of the economic impacts of Johne's disease indicated that reduced milk production, associated with the determination of dairy operations as Johne's-positive, reduced consumer surplus by 770 million dollars+/- 690 million dollars, and resulted in a total loss of 200 million dollars+/- 160 million dollars to the US economy in 1996. Most of the economic surplus lost by consumers was transferred to producers, whose economic surplus increased by 570 million dollars+/- 550 million dollars as a result of the reduced milk production associated with Johne's disease. Uncertainty analysis showed that the estimated reduction in milk production on Johne's-positive dairy operations accounted for most of the uncertainty in the economic-impact estimates. If Johne's disease had not been present on US dairy operations, then an additional 580 million+/-460 million kg of milk would have been produced, but the price would have fallen by 1.1+/-1.0 cents/kg, and the total value of the milk would have decreased by 580 million dollars+/- 560 million dollars.
Economic impacts of reduced milk production associated with epidemiological risk factors for Johne's disease on dairy operations in the USA.
An examination of the economic effects of epidemiologic risk factors for Johne's disease identified regional and herd size differences as having the greatest impact. Having dairy cows that were not born on the operation was the most important factor over which individual producers had the most immediate control. Economic consequences associated with using multiple-cow-maternity housing and multiple-preweaned-calf housing were not statistically significant. Economic welfare analysis was applied, and the GUM Workbench was used to analyse uncertainties in the estimates of the economic impacts.
Welfare effects of reduced milk production associated with Johne's disease on Johne's-positive versus Johne's-negative dairy operations.
An examination of the economic impacts of reduced milk production associated with Johne's disease on Johne's-positive and Johne's-negative dairy operations indicated that, if Johne's disease had not existed in US dairy cows in 1996, then the economic surplus of Johne's-negative operations would have been $600 million+/-$530 million lower, while the economic surplus of Johne's-positive operations would have been higher by $28 million+/-$79 million, which was not significantly different from zero. The data available for projecting changes in surplus were not sufficiently precise to allow an exact statement on whether Johne's-positive operations would have been better or worse off economically, in terms of the value received for producing more milk if they had not been affected by Johne's disease. The changes in producer surplus, based upon eliminating specific epidemiological risk factors for Johne's disease, were disaggregated between Johne's-positive dairy operations exposed to the risk factor and all other US dairy operations. Eliminating the risk factor of having any cows not born on the operation would have had a significant positive effect on the economic surplus of Johne's-positive operations that had any cows not born on the operation.
A method for predicting proportions of affected herds from proportions of affected animals.
The frequency of herds affected with 13 different diseases is shown to bear a simple relationship to the frequency of affected animals. The relationship seems to be useful for predicting proportions of affected herds.
Greater susceptibility to Mycobacterium johnei of C.57 black mice, when compared with CBA and Swiss white mice.
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Ovine Johne's disease in New Zealand.
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The effect of Johne's disease on production traits in Romney, Merino and Merino x Romney-cross ewes.
AIM: To quantify the effects of clinical Johne's disease on the performance of Romney, Merino and Merino x Romney-cross ewes. METHODS: The performance of ewes was compared using eight birth cohorts (1971-1978). Merino and Merino-cross genotypes included New Zealand Merino and Australian Superfine Merino sources. Intensive monitoring of Johne's disease was undertaken over the production years 1975-1982. Positive diagnostic evidence of Johne's disease was established post mortem from lesions of granulomatous enteritis associated with high numbers of acid-fast bacilli. Over years, data on a total of 2,341 Romney ewes and 1,292 Merino and Merino x Romney-cross ewes were recorded, consisting of annual records of liveweight (LWT), greasy fleece weight (FWT), number of lambs born per ewe per year (NLB), and lifetime productivity of ewes. RESULTS: A total of 82 (3.5%) Romney ewes and 62 (4.8%) Merino and Merino x Romney-cross ewes were diagnosed with clinical Johne's disease over the 8-year monitoring period, equivalent to 0.9% and 1.2% annual cases for these breeds, respectively, of the ewes present at mating. The percentage of clinical cases (p<0.04) and the age at death from Johne's disease (p<0.02) were lower for Romneys than for Superfine Merinos. The mean age of death from Johne's disease was 3.41 (standard error (SE) 0.06) years, lower than the mean disposal age from the flock of 5.03 (SE 0.02) years for clinically normal ewes (p<0.001). In their final year of production, ewes with clinical Johne's disease had lower LWT by 5.3 kg (10.5% of the mean; p<0.001), lower annual FWT by 0.54 (SE 0.10) kg (14.2%; p<0.001), fewer NLB by 0.15 (SE 0.07) lambs (13%; p<0.05), and lower litter weaning weights by 3.6 (SE 1.3) kg (15%; p<0.01) compared with clinically normal ewes. The size of the production losses associated with Johne's disease depended on the age to which ewes survived. Considering all production years of ewes (up to 8 years), the total weight of lambs weaned by ewes with clinical Johne's disease was 30.9 (SE 3.4) kg lower (46%; p<0.001) than the total from clinically normal ewes. CONCLUSIONS: Clinical Johne's disease led to significant losses in LWT, FWT, NLB, and in the lifetime production of ewes, amounting overall to a 46% reduction in productivity (p<0.001). CLINICAL RELEVANCE: Productivity losses from clinical cases of Johne's disease would be of considerable economic importance in flocks with a high incidence of the disease. The lack of good diagnostic tests for Johne's disease in the live animal, and the lack of active surveillance programmes, has made it difficult to establish the true prevalence of Johne's disease in sheep flocks in New Zealand, and its economic consequences.
UV-induced inactivation rates for airborne Mycobacterium bovis BCG.
Engineering ultraviolet irradiation systems as a control against infectious airborne diseases requires a knowledge of intrinsic ultraviolet (UV) inactivation rates of airborne bacteria. Ultraviolet inactivation rates for airborne Mycobacterium bovis bacillus Calmette-Guérin (BCG) were determined at 50% and 95% relative humidity (RH) in a 0.8 m3 bioaerosol reactor. Ultraviolet inactivation response of waterborne M. bovis BCG pure cultures was also determined. At 50% RH the airborne UV inactivation rates observed were two times greater than those observed in saturated air (RH = 95%), and rates at 95% RH were similar to those observed in otherwise identical cultures suspended in water. Intrinsic UV inactivation rates for M. bovis BCG were statistically similar to rates observed for Mycobacterium parafortuitum at 50% and 95% RH, indicating that M. parafortuitum is a valid surrogate for studying airborne UV responses of M. bovis BCG and Mycobacterium tuberculosis. Results also confirm that UV inactivation responses for bacteria suspended in water cannot be used to estimate UV dose response in unsaturated air.
Gut microbes, the innate immune system and inflammatory bowel disease: location, location, location.
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The growth of Mycobacterium tuberculosis and Mycobacterium johnei in a modification of Dubos medium.
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The chemical composition of wasting muscle in cattle suffering from clinical Johne's disease.
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The chemical composition and capacity for protein synthesis of the liver of cattle suffering from clinical Johne's disease.
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Malabsorption in Johne's disease in cattle: an in-vitro study of L-histidine uptake by isolated intestinal tissue preparations.
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The role of mycobacteria in Crohn's disease.
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Diagnosis of Johne's disease in cattle using mesenteric lymph node biopsy: accuracy in clinical suspects.
Histopathological examination of biopsies of mesenteric lymph node obtained from the region of the terminal ileum proved to be a very accurate method of diagnosing Johne's disease in the living animal. Identical conclusions were reached in 100 clinical suspects following examination of either mesenteric lymph nodes alone, or a wider range of routine specimens including ileum, caecum, colon and ileocaecal lymph nodes. A method of obtaining biopsy specimens from mesenteric lymph nodes is described and is recommended when an early definitive diagnosis is required.
Psychosocial investigation of individual and community responses to the experience of Ovine Johne's Disease in rural Victoria.
OBJECTIVE: This paper explores the psychosocial outcomes for individuals and communities in rural Victoria who experienced the outbreak of Ovine Johne's Disease (OJD). DESIGN: The study uses a qualitative methodology to analyse the minutes of evidence provided by the inquiry into the control of OJD to identify the psychosocial events, experiences and outcomes associated with the control of this outbreak. The inquiry was undertaken by the Environment and Natural Resources Committee of the Victorian State Government. SETTING: Public hearings were undertaken by the committee across several rural Victorian communities and the state capital, Melbourne. SUBJECTS: The transcripts detail 136 submissions from 98 individuals and 23 organisations. OUTCOME MEASURES: The analysis aimed to provide insight into the impact of the disease on individuals and communities and also to explore the factors individuals perceived as associated with these outcomes. RESULTS: While the paper identifies that aspects of stock loss associated with the outbreak caused substantial emotional and economic distress, for farmers the most significant finding was the impact of the government control program on individuals, families and rural communities. The control program was perceived as having very limited scientific credibility and its implementation was described as heartless, inflexible and authoritarian. Involvement with the program resulted in farmers reporting emotions, such as, trauma, shame, guilt and stigma. Families became discordant and the sense of community within rural townships fragmented. Psychological outcomes of grief, depression and anxiety emerged as prevalent themes within families and communities. CONCLUSIONS: These data highlight the need for significant attention to the management of rural disasters, such as, the OJD program. WHAT THIS PAPER ADDS: There is an acknowledgement in the literature that rural disasters have a significant impact on the well-being of individuals, families and communities. The major focus of the previous research has, however, been on the impact of economic losses with less recognition of the other psychosocial loss experiences that accompany the experience of rural disaster. This paper achieves a clear description of the experiences for individuals (trauma, stigma, sense of personal failure, loss of identity, diminished self esteem and family disruption) and communities (destroyed social cohesion, economic disharmony) caught up in the OJD disaster and explores the factors that individuals perceive as responsible for these outcomes. The mental health outcomes for individuals, such as, loss, grief and depression are also explored within this paper. This paper highlights the psychosocial complexity of the experience of rural disaster for individuals and communities significantly extending the current knowledge base in this area.
The avian tubercle bacillus and its relatives.
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