Feed intake and rumen motility in dwarf goats. Effects of some o -adrenergic agonists, prostaglandins and posterior pituitary hormones. Veterinary Research Communi&tions, 15 (l), 57-67
The purpose of the present investigation was to test the hypothesis that drug-induced changes in rumen co~tract$ns influence feed intake in dwa-$ goatsi Intravenous (ix) administration of c!midinT (1 /Lg kg min for 10 mm), xylazine (1 hg kg min for 10 min), and PGF-& (10 pg kg min for 15 min) 'caused bradycardia and inhibition of rumen contractions. However, no appetite-stimulating effect of these drugs was observed. Other clinical changes induced by the a -adrenergic agonists included slight sedation and a decrease in body temperature; alI-~linicaI1effects 08cIonidine and xylazine were partly antagonized by tolazoline pretreatment (10 pg kg min for 30 min). These results suggest that the CNS control of feeding differs in ruminants and monogastric species.
In dwarf goats fastef for 21h , i.v. administration of oxytocin (O.t3\ IU ILL-' min-' for 15 min), _ vasopressinl(O.?l~fU kg min for 15 min), octapressin (0.003 IIJ kg min (0.8 pg kg mm for 15 min) or PGE, for 15 min) did not change feeding behaviour during the two observation periods (O-30 min and 180-210 min after drug infusion, respectively). In previous studies, similar doses of these drugs induced changes in heart rate and inhibition of rumen contraction in goats. These findings demonstrate that drug-induced changes in forestomach contractions do not simp!$ cauy changes in feeding behaviour. Th-7 iv. infusion of the PGFzp analogues ettpyton -(,10 pg kg mm for 15 min), luprost$l (30 6 kg min-for 15 min), cloprostenol (1 Fg kg min for 15 min) and tiaprost (1 pg kg min for 15 min) induced hypophagic effects and stimulated intestinal propulsion.