Intoxicação por plantas que contêm nitratos em ruminantes no Nordeste do Brasil.

Abstract

The objective of this study was to investigate nitrate / nitrite intoxications in Paraíba and Pernambuco. In the first chapter, there are reports of outbreaks of Portulaca oleracea intoxication in goats and sheep in the states of Pernambuco and Paraíba. A model of experimental reproduction of intoxication has been developed and proven that the toxicose is caused by the high concentrations of nitrates present in the plant. The presence of nitrates in plant samples from several locations in the states of Pernambuco and Paraíba was verified through the diphenylamine test. In the second chapter, two outbreaks of nitrate and nitrite intoxication in cattle are reported in Paraíba, Northeast Brazil. The first was by Pennisetum purpureum (elephant grass) and the second by Pennisetum purpureum and Brachiaria sp (brachiaria grass) that occurred during the prolonged drought period. In the former the use of wastewater contributed decisively to the accumulation of nitrates. In the second, several risk factors, such as fertilization of chemical fertilizers, herbicides, fires and natural phenomena, were planted in the bed of the dam that was submerged for a long time and in an area that had a high amount of organic matter. Clinical signs were characterized by dyspnoea, cyanosis in the ocular mucosa, oral and vaginal, ataxia and falls that evolved to death. The presence of nitrate was detected in the two outbreaks by means of the diphenylamine test. The quantitative tests were performed in the second outbreak by means of a portable nitrate meter, where a high amount of nitrates was observed in the analyzed samples. The characteristic macroscopic findings, absence of microscopic lesions and response to methylene blue treatment were also decisive for the determination of nitrate and nitrite intoxication. It is concluded that the risk of occurrence of nitrate and nitrite intoxication in the Northeast is frequent, since there is a risk factor for nitrate accumulation in the plants and that the portable device is an excellent alternative for quantifying nitrates in suspect pastures.