FOOD-INTAKE AND RUMEN MOTILITY IN DWARF GOATS - EFFECTS OF ATIPAMEZOLE ON THE INHIBITORY EFFECTS INDUCED BY DETOMIDINE, MEDETOMIDINE AND ROMIFIDINE

The effects of some alpha2-adrenoceptor agonists and of the alpha2-adr enoceptor antagonist atipamezole on food intake and ruminal contractio ns were studied in dwarf goats. Detomidine, 0.2 mug/kg per min for 10 min, failed to modify food intake during either the first or second ob servation period (0-30 min and 180-210 min after drug infusion, respec tively). Given at a higher dose rate (0.4 mug/kg per min for 10 min), the drug inhibited food consumption during the first observation perio d, but stimulated food intake during the second period. A similar patt ern was observed after IV infusion with medetomidine (0.2 mug/kg per m in for 10 min), romifidine (0.4 mug/kg per min for 10 min) or xylazine (1 mug/kg per min for 10 min). The alpha2-antagonist atipamezole (2 m ug/kg per min for 10 min) failed to modify food intake during either t he first or second observation period. After treatment with atipamezol e, the effects of alpha2-agonists on feeding behaviour were completely antagonized. The alpha2-agonists administered at similar dose rates t o those used in the food intake experiments induced bradycardia, decre ases in body temperature and inhibition of ruminal contractions. The i nhibition of ruminal contractions induced by romifidine was partly ant agonized by atipamezole pre-treatment. These findings demonstrate that the alpha2-agonist-induced changes in ruminal contractions do not sim ply cause changes in feeding behaviour. The drop in body temperature i nduced by alpha2-agonists was prevented by atipamezole pre-treatment, whereas the induced bradycardia was not modified by this alpha2-antago nist.