EFFECTS OF MASH DIET AND PELLETS UPON DIGESTIVE MOTOR FUNCTIONS IN DOMESTIC HENS AND GUINEA HENS

The changes of gastric and intestinal motilities induced by food restriction and refeeding with pellets instead of an all-mash diet were compared in hens and guinea hens. Smooth muscle electrical activity was recorded in both species, which differed by their degree of domestication and food habits. Six-day fasting reduced gastric activity in both species, a phenomenon paralleled by an increase in intestinal motility and the disappearance of the diurnal cycles of gastro-intestinal activity. Refeeding increased gastric activity and reduced the intestinal activity in hens. By contrast with hens, pellets failed to induce major changes in the guinea hens, despite an increased frequency of gastric spike bursts and inhibition of the orad propagation of the intestinal spike bursts. The results suggest that hens, despite a lower responsiveness to environmental changes, are more sensitive than guinea hens to changes in diet. Key words: Birds, digestive electromyography, diet, physiological rhythms

A basic relationship between gastric and duodenal motilities in chickens.

Chickens were chronically fitted with a duodenal cannula and pairs of electrodes implanted in the wall of the muscular stomach, duodenum and ileum. Smooth muscle electrical activity was recorded in both fed and fasted conditions under a 12--12 h dark-light schedule. Two major patterns of activity were identified. The first consisted of spike bursts that propagated rapidly either aborally from the stomach or orally from the ileum. Aborad-propagated spike bursts were most frequent during the daytime; this circadian variation was abolished by vagotomy, which also increased the frequency of orad-propagated spike bursts. The second pattern was characterized by periods of repetitive spike bursts lasting 3--10 min and spreading aborally at a slower rate. In the fasted chicken, the daily frequency was increased and the period of repetitive spike bursts resembled the prolonged bursts of spike potentials recorded in the feline small intestine. The results suggest that the propulsion of digesta might depend on the ratio of spike bursts moving aborally from the stomach to those moving orally from the ileum. Both factors were influenced by the level of stomach activity.