Plantas tóxicas para bovinos em Mato Grosso.

Abstract

This thesis includes four articles related to plant poisoning in the State of Mato Grosso. A review of the main toxic plants in the Midwest region constitutes the first chapter. The second chapter consists of an article that refers to the description of an outbreak of acute poisoning by Pteridium arachnoideum and Pteridium caudatum in cattle, as well as the distribution of these plants in the State of Mato Grosso. Pteridium spp was observed in 83 properties in nine municipalities in Mato Grosso and from this total, samples from 22 properties were collected for taxonomic classification. In 22 properties P. arachnoideum was classified and in two of these properties there was also P. caudatum. In the property where the disease occurred, 306 cattle were introduced in a pasture formed by Brachiaria brizantha intensely invaded by P. arachnoideum and P. caudatum and of these 22 cattle became sick and died. The epidemiological, clinical and pathological aspects of this disease were described and discussed. The growing deforestation and the frequent use of fires in Mato Grosso may contribute to this disease becoming an important source of damage to the state's livestock. The third chapter describes the profile of 40 rural properties with pastures invaded by P. arachnideum in the northern region of Mato Grosso, as well as the prevalence of enzootic bovine hematuria (HEB) in dairy and beef cattle in this region. HEB was observed in 15/40 properties with prevalence varying between 0.8 and 16.6%. Aspects related to the implementation of pastures and management used were discussed. Most properties that presented HEB had pastures highly invaded by the plant, while most properties that never had animals affected by HEB had pastures with invaded areas below 10%. Deforestation and the use of fires were determining factors in the invasion of paddocks by P. arachnoideum. A study where six outbreaks of spontaneous poisoning by Senna obtusifolia were described, as well as the experimental reproduction of the disease, makes up the fourth chapter. Disease morbidity ranged from 2% to 27.9% and lethality was 100%. The disease affected a total of 30 cattle and, of these, eight were necropsied. For the experimental reproduction of the disease, green leaves and pods of S. obtusifolia collected at different times were administered to six cattle in daily doses totaling between 9% and 38% of body weight. Cattle affected by the spontaneous disease, as well as those experimentally intoxicated, showed clinical signs and lesions related to toxic myopathy and acute toxic hepatic necrosis. In this study, S. obtusifolia collected in the same area, but in different months or years showed variation in toxicity. Poisoning by S. obtusifolia is an important cause of death in cattle in the State of Mato Grosso. The disease caused by this plant in cattle is similar to intoxication by S. occidentalis, however in intoxication by S. obtusifolia, in addition to muscle lesions, commonly observed in intoxication by these two plants, acute hepatic necrosis can also be observed.