The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform

Robert Wagner - One of the best experts on this subject based on the ideXlab platform.

  • mycobacteriosis in zebrafish colonies
    Ilar Journal, 2012
    Co-Authors: Christopher M Whipps, Christine Lieggi, Robert Wagner
    Abstract:

    Mycobacteriosis, a chronic bacterial infection, has been associated with severe losses in some zebrafish facilities and low-level mortalities and unknown impacts in others. The occurrence of at least six different described species (Mycobacterium abscessus, M. chelonae, M. fortuitum, M. haemophilum, M. marinum, M. peregrinum) from zebrafish complicates diagnosis and control because each species is unique. As a generalization, mycobacteria are often considered opportunists, but M. haemophilum and M. marinum appear to be more virulent. Background genetics of zebrafish and environmental conditions influence the susceptibility of fish and progression of disease, emphasizing the importance of regular monitoring and Good Husbandry Practices. A combined approach to diagnostics is ultimately the most informative, with histology as a first-level screen, polymerase chain reaction for rapid detection and species identification, and culture for strain differentiation. Occurrence of identical strains of Mycobacterium in both fish and biofilms in zebrafish systems suggests transmission can occur when fish feed on infected tissues or tank detritus containing mycobacteria. Within a facility, Good Husbandry Practices and sentinel programs are essential for minimizing the impacts of mycobacteria. In addition, quarantine and screening of animals coming into a facility is important for eliminating the introduction of the more severe pathogens. Elimination of mycobacteria from an aquatic system is likely not feasible because these species readily establish biofilms on surfaces even in extremely low nutrient conditions. Risks associated with each commonly encountered species need to be identified and informed management plans developed. Basic research on the growth characteristics, disinfection, and pathogenesis of zebrafish mycobacteria is critical moving forward.

Christopher M Whipps - One of the best experts on this subject based on the ideXlab platform.

  • mycobacteriosis in zebrafish colonies
    Ilar Journal, 2012
    Co-Authors: Christopher M Whipps, Christine Lieggi, Robert Wagner
    Abstract:

    Mycobacteriosis, a chronic bacterial infection, has been associated with severe losses in some zebrafish facilities and low-level mortalities and unknown impacts in others. The occurrence of at least six different described species (Mycobacterium abscessus, M. chelonae, M. fortuitum, M. haemophilum, M. marinum, M. peregrinum) from zebrafish complicates diagnosis and control because each species is unique. As a generalization, mycobacteria are often considered opportunists, but M. haemophilum and M. marinum appear to be more virulent. Background genetics of zebrafish and environmental conditions influence the susceptibility of fish and progression of disease, emphasizing the importance of regular monitoring and Good Husbandry Practices. A combined approach to diagnostics is ultimately the most informative, with histology as a first-level screen, polymerase chain reaction for rapid detection and species identification, and culture for strain differentiation. Occurrence of identical strains of Mycobacterium in both fish and biofilms in zebrafish systems suggests transmission can occur when fish feed on infected tissues or tank detritus containing mycobacteria. Within a facility, Good Husbandry Practices and sentinel programs are essential for minimizing the impacts of mycobacteria. In addition, quarantine and screening of animals coming into a facility is important for eliminating the introduction of the more severe pathogens. Elimination of mycobacteria from an aquatic system is likely not feasible because these species readily establish biofilms on surfaces even in extremely low nutrient conditions. Risks associated with each commonly encountered species need to be identified and informed management plans developed. Basic research on the growth characteristics, disinfection, and pathogenesis of zebrafish mycobacteria is critical moving forward.

  • Distribution and genetic characterization of Mycobacterium chelonae in laboratory zebrafish Danio rerio.
    Diseases of aquatic organisms, 2008
    Co-Authors: Christopher M Whipps, Jennifer L. Matthews, Michael L. Kent
    Abstract:

    During routine screening of zebrafish at a research facility, histological changes consistent with mycobacteriosis were observed, prompting an investigation to determine the background prevalence and distribution of Mycobacterium species throughout the facility. Infection status was evaluated in 240 zebrafish representing 9 genetic lines, using histology, culture and PCR. Environmental sources were also tested for the presence of mycobacteria. Prevalence in zebrafish by culture and PCR was 10% (24/240), 21 of which were TU line fish. All isolates from fish were identified as M. chelonae by hsp65 DNA sequencing; subsequent DNA fingerprinting delineated 3 strains, designated H1E1 (1/24), H1E2 (22/24), and H1E3 (1/24). From external sources, tank or tubing surface biofilms were positive by culture (13/32) with multiple species and strains isolated including M. neoaurum, M. phocaicum, and identical strains of M. chelonae that were found in zebrafish: H1E1 (2/13) and H1E2 (8/13). Comparing diagnostic methods, acid-fast stained histological sections showed substantial agreement with plate culture and PCR for detection of mycobacteria in fish. Observation of granulomas in hematoxylin and eosin-stained sections was a less reliable predictor of mycobacteriosis, as uninfected females with egg-associated inflammation and hyperplasia were misdiagnosed. These data revealed background levels of mycobacteriosis in a healthy and well-managed facility. Infected populations were removed, although the apparent ability for M. chelonae to remain viable in environmental reservoirs may make it difficult to eradicate completely. This highlights the importance of an animal-health monitoring program and Good Husbandry Practices to prevent disease in zebrafish research laboratories.

Jet Mars - One of the best experts on this subject based on the ideXlab platform.

  • antimicrobial susceptibility of mycoplasma bovis isolates from veal calves and dairy cattle in the netherlands
    Veterinary Microbiology, 2016
    Co-Authors: A E Heuvelink, Constance Reugebrink, Jet Mars
    Abstract:

    Control of Mycoplasma bovis infections depends on Good Husbandry Practices and antibiotic treatment. To allow more prudent use of antimicrobial drugs, there is a need for information on the susceptibility profile of this pathogen. The objective of the present study was to analyse the in vitro antimicrobial susceptibility of clinical M. bovis isolates in the Netherlands. The collection comprised 95 bovine isolates, originating from lungs (n=56), mastitis milk (n=27), and synovial fluid (n=12), collected between 2008 and 2014. Minimal inhibitory concentrations (MICs) were assessed by broth microdilution, both by using in-house prepared MIC plates and by using commercially available MIC plates. For each antimicrobial agent, the range of MIC results, the MIC50, and MIC90 values were calculated. M. bovis strains recently isolated in the Netherlands appeared to be characterized by relatively high MIC values for antimicrobial agents that, until now, have been recommended by the Dutch Association of Veterinarians for treating pneumonia caused by Mycoplasma species. Fluoroquinolones appeared to be the most efficacious in inhibiting M. bovis growth, followed by tulathromycin and oxytetracycline. The highest MIC values were obtained for erythromycin, tilmicosin, and tylosin. Future studies should be done on determining M. bovis specific clinical breakpoints, standardization of methods to determine MIC values as well as molecular studies on detection of antimicrobial resistance mechanisms of M. bovis isolates to develop PCR assays for determining resistance.

Christine Lieggi - One of the best experts on this subject based on the ideXlab platform.

  • mycobacteriosis in zebrafish colonies
    Ilar Journal, 2012
    Co-Authors: Christopher M Whipps, Christine Lieggi, Robert Wagner
    Abstract:

    Mycobacteriosis, a chronic bacterial infection, has been associated with severe losses in some zebrafish facilities and low-level mortalities and unknown impacts in others. The occurrence of at least six different described species (Mycobacterium abscessus, M. chelonae, M. fortuitum, M. haemophilum, M. marinum, M. peregrinum) from zebrafish complicates diagnosis and control because each species is unique. As a generalization, mycobacteria are often considered opportunists, but M. haemophilum and M. marinum appear to be more virulent. Background genetics of zebrafish and environmental conditions influence the susceptibility of fish and progression of disease, emphasizing the importance of regular monitoring and Good Husbandry Practices. A combined approach to diagnostics is ultimately the most informative, with histology as a first-level screen, polymerase chain reaction for rapid detection and species identification, and culture for strain differentiation. Occurrence of identical strains of Mycobacterium in both fish and biofilms in zebrafish systems suggests transmission can occur when fish feed on infected tissues or tank detritus containing mycobacteria. Within a facility, Good Husbandry Practices and sentinel programs are essential for minimizing the impacts of mycobacteria. In addition, quarantine and screening of animals coming into a facility is important for eliminating the introduction of the more severe pathogens. Elimination of mycobacteria from an aquatic system is likely not feasible because these species readily establish biofilms on surfaces even in extremely low nutrient conditions. Risks associated with each commonly encountered species need to be identified and informed management plans developed. Basic research on the growth characteristics, disinfection, and pathogenesis of zebrafish mycobacteria is critical moving forward.

Gillah K. A. - One of the best experts on this subject based on the ideXlab platform.

  • Studies on productive and reproductive performance of crossbred dairy cattle in selected Urban and Peri Urban Areas of Tanzania
    Sokoine University of Agriculture, 2017
    Co-Authors: Gillah K. A.
    Abstract:

    PhD ThesisIn Tanzania, urban and peri urban dairying is commonly practiced by people from different socio-economic and cultural groups. This provides them regular income, employment opportunities and alleviates poverty. The demand for milk and milk products is high and this motivates farmers to increase their cattle herds in urban and peri urban areas. Despite the high demand for milk and milk products, the average daily milk yield, quality of milk and reproductive performance of crossbred dairy cows is low due to management factors, poor quality feeds and feeding of the dairy cattle. In order to address some of the challenges to high milk production and reproduction performance of cows, a series of studies were undertaken in urban and peri urban areas of Dar es Salaam city and Morogoro municipality. In this study an in-depth literature review on urban and peri urban dairy farming in East African cities was done (Paper I). The results revealed that urban and peri urban dairy production system is very common in all East African cities but significantly varying in intensity. Dairy cows were fed on forages that contained 6 to 6.8%CP and produced average milk yield that ranges from 5.7–17.1 litres/cow/day. The range for lactation lengths, ages at first calving, calving to conception interval, calving interval and number of services per conception of crossbred dairy cows were 8.8 to 11.2 months, 29.7 to 46.0 months, 123 to 276 days, 406 to 562 days and 1.7 to 2.3, respectively. The trend in average milk yield and reproductive performance of the dairy cows was not clear. The major constraints hindering dairy production in East African cities differed between and within countries and production systems due to differences in data collection, physical locations, dairy breeds kept and seasons of the year. In the second study (Paper II and III), a cross sectional study using a random sample of 153 dairy farmers in Dar es Salaam city (71) and Morogoro municipality (82) was done by collecting data on management and production levels of dairy cattle. The two study sites fall under the same agro ecological zone and were meant to compare the performance of dairy cows. The results showed that one third of farmers practised free grazing system and dairy cows were mainly fed low quality forage and energy concentrate. Forage/fodder was collected from communal areas and dairy farmers in Dar es Salaam city covered significantly longer distance (14.7±1.2 km) than Morogoro municipality (3.07±1.2 km). Steaming up of dry cows was fairly common among dairy farmers in Dar es Salaam city but rarely done in Morogoro municipality. Artificial insemination service was not a common breeding method in the study areas. Over half of the cattle sheds had high stocking density and were poorly designed (Paper III). Dairy cows produced significantly higher average milk yield in Dar es Salaam city (10.5±1.2 litres/cow/day) than in Morogoro municipality (6.2±0.4 litres/cow/day). One third of the dairy farmers (29.2 percent of 153 respondents) planned to decrease their cattle herds, many of them from Morogoro municipality (16.0 percent of 153 respondents) due to shortage of feeds. The third study (Papers IV) was based on a longitudinal study design in which 60 dairy farmers with a total of 309 dairy cattle were monitored for nine (9) months to assess effect of management on chemical composition of milk and to quantify the microbial load of raw milk. Dairy cows were monitored during the wet and dry seasons to capture seasonal effect on milk yield and quality. The results showed the average milk yield to be 7.0±0.1 litres/cow/day and was significantly affected by parity, stage of lactation, season of calving, employment status of the farmers and means used to collect forage from the sources to the dairy units. However, milk yield was not influenced by grazing systems, breeds of the cows and types of farm labour. Dairy cows in the third parity, dairy cows owned by self-employed farmers and dairy farmers who used bikes to collect forage produced 7.8±0.2, 7.5±0.5 and 6.7±0.5 litres/cow/day higher than dairy cows in other parities, dairy cows owned by government-employees and dairy farmers who used cars to collect forage, respectively. The wet season had significantly higher total bacterial counts (5.9±0.04 log10cfu/ml) and coliform counts (2.4±0.08 log10cfu/ml) than 5.7 ±0.04 log10cfu/ml and 2.0±0.08 log10cfu/ml bacterial counts and coliform counts, respectively observed in the dry season. However, grazing systems had no significant effect on microbial load. Stocking density significantly influenced total bacterial counts but not coliform counts. Further, employment status of the dairy farmers and source of farm labour had no effect on bacterial loads. Lastly, study four (Paper V) evaluated the effects of pre partum concentrate supplementation on milk yield, milk chemical composition and reproduction of crossbred dairy cows. The cost of concentrate supplementation of different treatment groups was also analysed. In this study, 48 dry crossbred cows in their last stage of gestation were used and divided into three groups according to concentrate supplementation and lasted for 24 weeks of lactation. The first treatment group was fed 4 kg/day of home-made ration during pre- and post-partum period (HMR-PPP) while the second group was fed a similar amount as the first group, but during the post-partum period (HMR-PP) only. The third group was a control and was fed maize bran 4 kg/day during the post partum period only (MB-PP) and simulated the farm’s feeding practice. The results on this study have shown that dairy cows supplemented with home made ration during pre and post-partum had significantly higher (8.5±0.3 litres/cow/day) milk yield followed by post-partum supplemented cows (6.2±0.3 litres/cow/day) with home-made ration. The control group which simulated farm's feeding Practices had the least milk yield (4.5 litres/cow/day). Concentrate supplementation had significant effect on percent total solids but not on percent butter fat and percent solids not fat. Effect of breed was significant on percent butter fat and percent total solids but not on percent solids not fat. Parity had a significant influence on percent total solids but not on percent butter fat and percent solids not fat. Breed had no significant effect on milk yield while parity significantly influenced milk yield. The supplementation regime and breed of dairy cows had no significant effect on number of services per conception, interval from calving to first insemination, interval from calving to conception and calving interval. Supplementing dairy cows with home made concentrates during both pre and post-partum periods was cost effective and economical compared to post-partum concentrate supplementation alone. It is concluded that the production levels are lower than 15 l/cow/day expected to be produced by crossbred dairy cows. However, the production levels can be improved through strategic concentrate supplementation coupled with Good Husbandry Practices. The microbiological quality of the milk was relatively poor. There is a need therefore to train dairy farmers on dairy cattle Husbandry and the importance of clean milk production in order to safe guard the consumers of milk and milk products