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Subject: search.filters.subject.Pithomyces chartarum

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    Management of facial eczema : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies in Epidemiology at Massey University, Manawatu, New Zealand
    (Massey University, 2016) Boyd, Emma
    Facial eczema is a hepatogenous photosensitisation of ruminants caused by sporidesmin produced by the saprophytic fungus Pithomyces chartarum. It is of large concern to the dairy industry, both with its effects on production and the significant animal welfare implications of affected stock. In 2011 DairyNZ and Sustainable Farming Fund invested in research initially aimed at trying to get a better understanding behind the natural spore count variability in paddocks, between paddocks and between farms and to try and find alternative ways of managing facial eczema without zinc. After this research was completed in 2013 it was deemed necessary to try and understand to what extent management of facial eczema was breaking down and possible reasons for these breakdowns. The overall aim of this research was to try and help farmers improve their management of this disease and reduce incidence of facial eczema. A study comparing the spore counts from paddocks containing varying quantities of herbs, clovers and tall fescue showed that the addition of chicory, plantain, lucerne and white clover into a ryegrass pasture did not provide any reduction in spore counts. Tall fescue paddocks showed lower spore counts over time than pure swards of ryegrass. A study comparing the application of lime and nitrogen in comparison to control paddocks showed that application of lime before the risk period for facial eczema (in November), application of lime after a spore count rise, (in March) or urea application (in December) did not affect the number of spores produced by Pithomyces chartarum. A study investigating the variability of spore counts within farm, paddock, grass sample and water aliquot showed that if spore counts are to be used for monitoring purposes to identify when to start and finish facial eczema(FE) prevention programmes, at least three aliquots per wash water should be selected. Finally, a study looking at the different types of management of FE used and their effectiveness highlighted that FE management on dairy farms in New Zealand could be substantially improved; principally through farmers getting more information on the success of their FE management programs and responding when tests show that FE management is not effective.
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    Optimisation studies of an atoxigenic strain of Pithomyces chartarum in submerged fermentation : a thesis presented in partial fulfillment of the requirements for the degree of Master of Technology in Biotechnology, Massey University, Palmerston North, New Zealand
    (Massey University, 1999) Ludemann, Geoffrey D.
    The conditions for maximum biomass concentration and propagule production by an atoxigenic strain of Pithomyces chartarum were investigated, in shake-flask and submerged fermenter. On the shake-flask scale, a variety of carbon sources, nitrogen sources, growth additives and pH values were studied as medium components and conditions. The dry weight biomass and the rate of substrate utilisation were used to assess the growth of the organism, while the number of colony-forming-units per unit volume was also determined following a standard homogenisation procedure, to monitor organism viability. The organism was shown to be capable of utilising a wide range of nutrient sources. Glucose and casamino acids were the best carbon and nitrogen sources, respectively, while the optimum culture pH value was in the broad range pH 4 to 7. The effect of growth additives was negligible. The performances of different strains of the organism on the semi-defined medium were compared and two of the three strains tested grew to desirable parameters. The third strain, however, was reluctant to sporulate despite repeated efforts. This non-sporulating strain did produce the greatest biomass concentration however. Following the establishment of a semi-defined medium, a possible production medium was formulated by replacing the nutritional components of the defined medium with low-cost complex substrates. The use of whey permeate was investigated for this role. The results showed that whey permeate alone was a poor medium; however when supplemental carbon sources, such as starch or sucrose, were added, the viability counts and biomass produced were the greatest yet achieved. Studies of the effect of agitation, aeration and inoculum size were conducted in small-scale submerged fermentation. This technology was demonstrated to be satisfactory for production of P. chartarum biomass. In the range of these variables studied, however, there was little effectnoted on the viability or biomass concentration produced. Finally, the effect of storage of the harvested biomass on its viability was studied. It was shown that the viability of the organism decreased markedly with storage over a 3-month period, and that the preserving techniques tested had little effect in reversing this trend.