Comparison of the sensibility of cattle and buffaloes to poisoning by Palicourea marcgravii (Rubiaceae).

In order to verify if buffaloes are more resistant than cattle to poisoning by Palicourea marcgravii,the plant was given per os simultaneously to buffaloes and cattle. Seven buffaloes and three head of cattle were used. Doses of 0.5, 1.0 and 2.0 g/kg did not cause signs of poisoning in buffaloes; but doses of 3.0, 4.0 and 6.0 g/kg caused death. in cattle 0.25 g/kg did not cause symptoms; but 0.5 and 2.0 g/kg were lethal. The influence of exercise on the onset of symptoms, the time which elapsed from the beginning of the administration of the plant to the appearance of symptoms, and the symptoms themselves, were similar in the two animal species. The clinical course was longer in buffaloes; whilst in cattle the period between the onset of severe symptoms and death lasted 9 to 17 minutes; in buffaloes it varied from 10 minutes to I hour 28 minutes. It can be concluded, that buffaloes are about six times more resistant than cattle to the toxic action of R maracgravii. The lower incidence of deaths in buffaloes by poisonous plants in the Amazon region is, at least in part, due the lower sensibility of buffaloes to poisoning by this plant. Another factor responsible for the smaller number of buffaloes which die due to plant poisoning in the Amazon region, is possibly that buffaloes prefer the lowlands, e.g. temporarily flooded areas, which are the habitat of Arrabidaea bilabiata, the second most important poisonous plant of the Amazon region. This plant is less poisonous than P marcgravii, and its habitat are the higher not flooded areas. So it would be safer, in order to diminish losses, to breed buffaloes instead of cattle in areas where P marcgravii occurs. The reason for the greater resistance of buffaloes should be further investigated as a possible prophylactic measure to avoid poisoning by P marcgravii in cattle. On the other hand, Australian investigators modified genetically the ruminal bacteria Butyrivibrio fibrisolvens by introducing a gene, isolated from a Moraxella sp, which codifies a dehalogenase, capable of hydrolyzing fluoroacetate, the poisonous principle of R marcgravii. Transferring the genetically modified B. fibrisolvens into the rumen of animals, which consume plants that contain fluoroacetate, would be a viable method to control that poisoning through a ruminal detoxifying process for the toxin. Through preliminary contacts, the director of the consorcium in Australia, responsible for the modification of the bacteria, declared that he is interested to sell the technology to our country, but it would be necessary to know if it is permitted to introduce into Brazil the genetically modified bacteria. If allowed, it would be necessary to perform investigations on the viability and the methodology for using this bacteria to control P marcgravii poisoning in our country.