Three outbreaks of nitrate poisoning are reported from the semiarid region of the state of Paraíba, northeastern Brazil. One outbreak caused by Echinochloa polystachya (capim-mandante) and two others caused by Pennisetum purpureum (capim-elefante) occurred at the end of the dry season, after the first rains. In one of the outbreaks caused by Pennisetum purpureum part of the pasture had been fertilized with cattle manure. Five out of 11 cattle died on one farm, 27 out of 81 on another, and 3 out of 9 on a third one. Clinical signs were anorexia, respiratory distress, teeth grinding, depression or hyperexitability, tremors, abdominal contractions, salivation, nasal discharge, uncoordinated gait, cyanosis, and finally recumbency. Nitrates and nitrites in the blood of affected cattle and pastures were determined by the diphenylamine test. It is suggested that the main reason for nitrate accumulation in the grasses was the prolonged draught followed by rain. In one of the outbreaks caused by Pennisetum purpureum, another reason was probably the fertilization of the soil with cattle manure.
Nitrate poisoning; Echinochloa polystachya; Pennisetum purpureum; capim-elefante; capim-mandante
