Some Functions of the Large Intestine of the Horse

Abstract

1. Techniques are described for cannulating the cæcum, ventral and dorsal colon of the horse. 2. Cæcal and colonic movements consisted of irregular contractions of which three types were recognized. Withholding food caused reduction in frequency or cessation of all contractions of cæcum and ventral colon; the dorsal colon remained unaffected. No evidence was obtained of antiperistaltic movements, as judged by the movement of carbon granules. 3. Adrenaline inhibited and carbamylcholine increased the frequency of the contractions. Histamine and posterior pituitary extract inhibited movements. 4. The concentration of volatile fatty acid in the liquor of the cæcum and ventral colon was decreased by withholding food and increased by feeding. This effect was not marked in the dorsal colon. The proportion of propionic acid in the ventral colon was greater than in the dorsal colon. 5. The rate at which cotton‐threads disintegrated when suspended in the cæcum, ventral and dorsal colon decreased in an oral‐caudal direction. Withholding food greatly reduced the rate of disintegration.

Cellulolytic Bacteria Isolated from the Large Intestine of the Horse

“…As digesta did not remain for longer than 22 h in the digestive tract of the horse (Alexander & Bernie, 1951), and cotton threads suspended in the horse colon were almost completely digested in 48 h (Alexander, 1952), the problem remains why cellulolytic activity in witro should require a t least several days to be manifest. It has been observed (Alexander, 1952) that, when food was withheld from the horse for 24 h, the disintegration of cotton thread in the large intestine almost stopped.…”

“…As digesta did not remain for longer than 22 h in the digestive tract of the horse (Alexander & Bernie, 1951), and cotton threads suspended in the horse colon were almost completely digested in 48 h (Alexander, 1952), the problem remains why cellulolytic activity in witro should require a t least several days to be manifest. It has been observed (Alexander, 1952) that, when food was withheld from the horse for 24 h, the disintegration of cotton thread in the large intestine almost stopped. Since it is unlikely that withholding food would cause the disappearance of cellulolytic bacteria from the tract, it seems probable that the nutritional requirements of the cellulolytic bacteria are very exacting and that their activity is closely associated with other concurrent digestive processes in the tract.…”

Factors Affecting the Blood Sugar Concentration in Horses

“…Ileal contents were obtained by introducing a hypodermic needle of 2 mm. bore into an exteriorized loop of ileum, prepared in the manner described previously , and caecal contents from a pony fitted with a permanent cannula in the caecum [Alexander, 1952]. Sodium fluoride was omitted from samples intended for the yeast fermentation experiments.…”

“…In these experiments, a little wellwashed brewer's yeast was added to the blood or other fluid and the sample incubated overnight at 370 C. Tubes containing a pure solution 24 of glucose with and without yeast were treated in the same fashion. Total volatile fatty acids were estimated in the manner already described [Alexander, 1952]. In the experiments in which glucose was administered, this substance was given by stomach tube in a 50 per cent (W/V) solution except for a few experiments in which solid glucose was fed.…”

Action de l’adrénaline et de quelques sympathomimétiques sur la motricité digestive des Equidés

“…Dans } 'intervalle, il est paru sur ce même sujet un travail de SIMONNET et collaborateurs (12) qui ont opéré sur des chevaux anesthésiés, et des publications d 'ALEXANDER (2,3,4) qui a tra vaillé sur des animaux à fistule permanente. Bien que nos résul tats soient en accord avec ceux de ces auteurs, nous croyons utile de les publier car, d'une part, il les complètent dans une certaine mesure, d'autre part, l'expérience que nous avons acquise des effets dü l'adrénaline sur l'appareil digestif des Ruminants nous incite à tirer des faits observés des conclusions un peu différentes.…”