Controle da intoxicação por Palicourea aenofusca.

Abstract

Palicourea aeneofusca (Müll. Arg.) Standl. contains sodium monofluoracetate (MFA) and when administrated at doses of approximately 0.6 g\kg body weight (g/kg) causes sudden death precipitated by exercise in goats and cattle. This dissertation if formed by two papers. The first entitled Conditioned Food Aversion for the Control of Palicourea aeneofusca Poisoning submitted to the Brazilian Journal of Veterinary Research was tested the possibility to induce conditioned food aversion to this plant in goats. For this, 0,35 g\kg of green leaves of P. aeneofusca were given to six goats on days 1, 5, 10, 20, 30, 60 and 90 after the start of the experiment. On the first day all goats ingested the full amount of the plant and were treated immediately with 175 mg\kg bw of litium chloride (LiCl) through a ruminal tube. On day 5th only two goats ingested the plant and were treated again with the same dose of LiCl. On days 10, 20, 30, 40, 60 and 90 none of the goats ingested the plant. To another group of six similar goats the plant was given on days 1, 10, 20, 30, 60 and 90. All goats ingested the plant on day 1 and received 1 mL/kg bw of water through a ruminal tube. All goats returned to ingest the plant on days 10, 20, 30, 60 and 90. These results demonstrated that it is possible to induce conditioned food aversion to P. aeneofusca for at least 90 days administrating LiCl after the ingestion of low non toxic doses of the plant. In the second paper, entitled Induction of Resistance to Palicourea aeneofusca (Rubiaceae) Poisoning by the Continuous Administration of Non-Toxic Doses, submitted to the Brazilian Journal of Veterinary Research, was tested the hypothesis that repeated non-toxic doses of Palicourea aeneofusca criam resistência à intoxicação. For this, 12 goats were distributed in two similar groups. In Group 1, resistance was induced by the administration of the dry plant, during four alternate periods: 0.02 g/kg during 5 days, 0.02 g/kg during 5 days, 0.03 g/kg during 5 days, and 0.03 g/kg during 5 days. Between the first and second period of administration and between the second and the third period the goats did not ingest P. aeneofusca for 10 days. Between the third and the fourth administration period the goats did not ingest the plant during 15 days. One goat died suddenly during the third administration period when was ingesting 0.03 g/kg. The goats from Group 2 were not adapted to the consumption of P. aeneofusca. Fifteen days after the end of the adaptation period in Group 1, both groups ingested dry P. aeneofusca in the daily dose of 0.03g\kg during 19 days. From day 20 the daily dose was increased to 0.04 g/kg, which was ingested for 12 days. The goats that showed clinical signs were removed from the experiment immediately after the observation of first signs. One goat from Group 2 showed clinical signs of poisoning and died on the 12th day of ingestion, and two showed clinical signs on day 24th; one recovered and the other died. At the end of the 31 days administration period, a new group (Group 3) with three goats was introduced in the experiment to investigate if the goats that did not become poisoned in Group 2 had acquired resistance. The three goats from Group 1, five goats from Group 1, and three from Group 2 started to ingest a daily dose of 0.06 g/kg of dry P. aeneofusca. On the third days of ingestion the three goats from Group 3 showed clinical signs. Two died suddenly and another recovered 10 days after the end of ingestion. All goats of Groups 1 and 2 ingested 0.06 g/kg/day during nine days without showing clinical signs. These results demonstrated that non-toxic repeated doses of P. aeneofusca increase significantly the resistance to the poisoning, and that this technique can be used to control the poisoning by P. aeneofusca or other toxic Palicourea species.