Made available in DSpace on 2016-04-28T20:16:32Z (GMT). No. of bitstreams: 1 2009 - Josilene Nascimento Seixas.pdf: 4044215 bytes, checksum: dfe1223a8c9106028077731ca7dd2fe5 (MD5) Previous issue date: 2009-02-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Numerous outbreaks of photosensitization in herbivorous animals maintained on Brachiaria pastures occur in Brazil, and the economic losses caused are of great concern due to the large areas in the country planted with this grass. The vast majority of outbreaks has been attributed to the sporidesmin containing spores of Pithomyces chartarum, a fungus which occurs in many countries of temperate climate. However, there are differences between the liver lesions in animals that develop photosensitization on pastures of Brachiaria spp and the ones described in P. chartarum poisoning. In several outbreaks reported from Brazil, no evidence for toxicity of the spores was revealed. As the isolation of toxic saponins from Brachiaria grasses has been reported in the literature, the real cause of the photosensitization in Brazil needs to be clarified, in order to be able to adopt correct preventive measures to avoid the condition. The main objective of this study was to show the different epidemiological, clinical, pathological and toxicological aspects of the two poisonings, based on data from the literature and our own observations of pithomycotoxicosis in Portugal and on the data of the photosensitization which occurs on Brachiaria pastures in Brazil. We concluded that the saponin content of the grass is be responsible for the outbreaks of photosensitizing disease which occur annually on Brazilian pastures. / Numerosos surtos de fotossensibiliza??o em animais mantidos em pastos de Brachiaria spp v?m ocorrendo no Brasil e as perdas econ?micas resultantes t?m sido foco de preocupa??o, em especial devido ?s grandes ?reas cultivadas dessa gram?nea no pa?s. A maioria dessas ocorr?ncias vem sendo atribu?das ? esporidesmina, presente em esporos do fungo Pithomyces chartarum, que ocorre em muitos pa?ses de clima temperado. No entanto, h? diferen?as entre o aspecto an?tomo-histopatol?gico verificado no f?gado de animais que desenvolvem fotossensibiliza??o em pastos de Brachiaria spp e o descrito na intoxica??o por P. chartarum. Nos diversos surtos relatados no Brasil n?o se conseguiu demonstrar a toxidez dos esporos. Como o isolamento de saponinas t?xicas tem sido reportado em pastagens de Brachiaria, a causa dos surtos de fotossensibiliza??o no Brasil precisa ser esclarecida, para que corretas medidas preventivas sejam adotadas e, a doen?a evitada. Este trabalho tem por objetivo principal demonstrar, atrav?s das diferen?as epidemiol?gicas, cl?nico-patol?gicas e toxicol?gicas peculiares ?s duas condi??es, colhidas na literatura e confrontadas com nossas pr?prias observa??es sobre pitomicotoxicose em Portugal e intoxica??o pela Brachiaria sp no Brasil, que as saponinas contidas na Brachiaria sp s?o respons?veis pelos surtos de fotossensibiliza??o que ocorrem anualmente nas pastagens brasileiras.