Factors affecting forestomach motility and food intake in goats [Sudan]

Well trained goats with rumen cannulae were used to investigate the effects of feeding levels on forestomach motility and rumination during ad libitum and deprived feeding regime. They were also used to investigate the effect of intravenous infusion of individual and mixture of volatile fatty acids, intravenous infusion of glucose and injection of a2-adrenergic drugs on forestomach motility rumination and food intake. Forestomach motility recorded was characterized by the A and B sequence of contractions. The pattern of reticular movement during feeding was biphasic where as during rumination it was triphasic. Feeding and rumination were associated with increase in the frequency of forestomach motility compared with the rest period, also the amplitude was highly increased during feeding and declined thereafter. Rumination exhibited a lag perio, during the first hour of feeding. Deprivation of food for three days resulted in reduction of the amplitude and rumination contractions, but the frequency of contraction was not significantly affected. Water deprivation for 3 days resulted in increased number of B-sequence of contraction and decreased the number of rumination contractions.Intravenous infusion of mixture of acetate, propionate and butyrate for one hour at the rate of 1m.mol.min-1 caused significant (P0.005) reduction in forestomach motility and food intake. Intravenous infusion of individual VFA at the rate of 1m.mol.min-1 resulted in different inhibitory effect, infusion of propionate alone depressed forestomach motility and caused periods of complete inhibition in all goats. It significantly (P0.005) reduced forestomach motiltiy and food intake. Butyrate infusion resulted in a reduction of forestomach contractions to complete inhibition and significantly (P0.005) affected forestomach motility and food intake. Acetate infusion resulted in a reduction of amplitude in one goat, complete inhibition was not observed. Forestomach contractions and food intake were not affected significantly although acetate plays insignificant role in food intake. The three major VFA were involved in the short term control of food intake. The duration of inhibited motility was significantly increased (P0.05) during infusion of VFA mixture, but not during the individual VFA. Intravenous infusion of glucose (0.278 mol/L) at a dose rate of 2ml.min-1 for 1/2 hour had no effect on forestomach motility or food intake. It appears that glucose plays an insignificant role in control of food intake in ruminants. Injection of the adrenergic drugs xylazine (0.3 mg/kg) intramuscularly caused a progressive inhibition of forestomach motility. Pretreatment of goats with Yohimbine (0.25 mg/kg) injected intravenously reduced the inhibitory action of xylazine. This shows that a2 adrenoreceptors are involved in regulation of forestomach motility in goats