Brachiaria species are the most important grasses for cattle production in Brazil. However, a limiting factor for the use of Brachiaria spp. is their toxicity. Most outbreaks of hepatogenous photosensitization are caused by B. decumbens; however B. brizantha, B. humidicola and B. ruziziensis can also cause poisoning. The poisoning affects cattle, sheep, goats and buffalo. Sheep are more susceptible than other animal species and the young are more susceptible than adults. There are differences in susceptibility among animals of the same species and it has been suggested that this resistance is genetic. Also has been suggested that buffalo and probably some sheep are resilient, i.e. when poisoned these animals have histologic lesions and high GGT serum concentrations, but do not show clinical signs. In general, saponin concentrations are higher in growing plants, but outbreaks occur all over the year, probably due to unexplained rise in saponin concentration in the plant. A clinical syndrome of progressive weight loss and death, without photosensitization, has been reported in cattle poisoned by B. decumbens. Main preventive measures are based on the selection of resistant or resilient animals and on the development of Brachiaria species or varieties with low saponin concentration.

Pesq. Vet. Bras. 32(12):1272-1280, dezembro 2012 1272 RESUMO.-Brachiaria spp. é a principal forrageira utilizada para ruminantes no Brasil Central, mas a sua toxicidade, devida à presença de saponinas esteroidais, torna-se um importante entrave à sua utilização. Neste trabalho descrevem-se 34 surtos e um foco de intoxicação por Brachiaria spp em ovinos, que ocorreram em diferentes épocas do ano. is the main pasture for ruminants in Central-Brazil, but the crucial problem for their utilization is the toxicity due to the presence of steroidal saponins. This paper reports 35 outbreaks of poisoning by Brachiaria spp in sheep. The poisoning occurred in different seasons of the year. Mean morbidity was 23.2% and mean lethality was 88.3%. The occurrence of clinical signs after the introduction of the sheep into the pastures varied from 15 days to more than 12 months. In 90.1% of the outbreaks, sheep younger than 12 months of age were affected. Clinical signs and gross lesions were characteristic of hepatogenous photosensitization, but more acute cases showed edema of the face and ears, without dermatitis or jaundice. The main histologic lesions of the liver were the presence of macrophages with foamy cytoplasm, found mainly in sinusoids, and sometimes containing negative images of crystals. In eight out of 11 farms visited the outbreaks occurred in Brachiaria decumbens pastures, two in B. brizantha pastures, and one in a pasture of B. decumbens, B. humidicola, and Andropogon sp. Saponin concentrations in the pastures of 11 outbreaks varied from 0.3 to 2.56%. The information generated by this report allows the proposal of measures for control and prevention of Brachiaria spp. poisoning in Central--Brazil.

This chapter presents experiments aiming to examine the aspects of Brachiaria spp. poisoning in sheep in Brazil, and analyse the epidemiological records from spontaneous outbreaks. The susceptibility of sheep to signal grass (Brachiaria decumbens [Urochloa decumbens]) poisoning, the effect of signal grass maturity on poisoning in naïve sheep and the performance of sheep grazing Brachiaria spp. and other pastures are described. It is shown that the susceptibility or resistance to Brachiaria spp. poisoning in sheep is complex and is probably influenced by genetic and acquired resistance and factors determining the saponin concentration in grasses. Nevertheless, Brachiaria spp. is an important option for grazing sheep in central-western Brazil. Therefore, more research is necessary to develop management measures to prevent the intoxication.

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A oestrose é uma miíase obrigatória e cavitária de ovinos e caprinos, domésticos e selvagens, causada por larvas da mosca Oestrus ovis (Linnaeus). Este estudo relata a presença de O. ovis na região Centro-Oeste do Brasil como parasitas de caprinos e ovinos. Nós obtivemos seis larvas de ovinos e caprinos suspeitos de oestrose em Brasília. As larvas originaram duas moscas fêmeas adultas de O. ovis, após 20 e 23 dias respectivamente. Este achado está provavelmente associado à expansão e diversificação da agricultura no cerrado do planalto central brasileiro. Ovis aries (Artiodactyla: Bovidae) and Capra hircus (Artiodactyla: Bovidae) infected by Oestrus ovis (Diptera: Oestridae) in the Federal District, Brazil Abstract. The Oestrosis is an obligatory and cavitary myiasis of sheep and goat, wild and domestic, caused by the larvae of Oestrus ovis (Linnaeus) fly. This study records the presence of O. ovis in the West Central region of Brazil as parasites of goats and sheep. We obtained six larvae from sheep and goats with suspects of oestrosis in Brasília (Brazil) originate two females adult of O. ovis, after 20 and 23 days respectively of pupation. This finding is probably associated with expansion and diversification of farming in the Cerrado of the Brazilian central plateau.