FACTORS DETERMINING GASTkOINTESTINAL TRANSIT TIME OF SEVERAL MARKERS IN THE DOMESTIC FOWL

Abstract

SUMMARYThe aim of this study was to find out how marker characteristics could affect digestive transit time in Gallus gallus. One soluble marker, Cr-EDTA, and two insoluble markers, Cr203 and chromium-mordanted plant cells of two sizes, were used. Three-to six-week-old chickens were killed in series after the oral administration of the markers at intervals of 0, 0 5, 1, 2, 3, 5, 7, and 9 h. The amount of chromium in each digestive segment was determined by atomic absorption. There were some differences in the initial distribution of markers: whereas almost the total amount of the chromium-mordanted rice husk of the largest size was found in the crop at time 0, less than half of the Cr-EDTA was found. Marker emptying out of the crop was fast and not related to either the type or size. In contrast, the emptying rate of the gizzard depended on marker particle size. As far as the caeca were concerned, the ileocaecal junction allowed the passage of soluble Cr-EDTA whereas solid markers were impeded (Cr2O3) or not allowed to pass through at all (vegetable fibre of any size). It can be concluded that marker selection is of major importance to transit time studies in chickens, since its characteristics can determine transit time in an absolute way.

Comparison of gastrointestinal transit times between chickens from D+ and D− genetic lines selected for divergent digestion efficiency

“…It was previously proposed that, in chickens, particles are delivered from the gizzard to the duodenum only if their size is lower than a critical value (Vergara et al, 1989a). According to our results, it can be hypothesized that this critical size was smaller in D 1 than in D 2 birds, and was decreased by particle stimulation only in D 2 birds.…”

“…Moreover, Vergara et al (1989a) observed a much longer retention time for the liquid phase entering the caeca. In fact, caeca MRT measured in our experiment represented a mean value taking account of all particles, including those entering the caeca and those not entering the caeca.…”

“…Besides such economic interest, D 1 and D 2 lines also represent a unique model for the study of physiological and genetic limiting factors of digestion. The latter interest is reinforced by the fact that total digestion in chickens is rather similar to ileal digestion in monogastric mammals, since digestion in the caeca and colon is very limited in chickens (Vergara et al, 1989a).…”

“…The stomach of chickens is divided into two compartments, the proventriculus or glandular part where the secretions of HCl and pepsinogen occur, and the gizzard or muscular part where the digesta are ground (Duke, 1986). Gizzard emptying in the duodenum is controlled by the pylorus that allows particles to move to the duodenum once they reach a critical size (Ferrando et al, 1987;Vergara et al, 1989a).…”

Is sequential feeding of whole wheat more efficient than ground wheat in laying hens?

“…Its purpose is to make them suitable for intestinal digestion by muscular activity. Vergara et al (1989) observed that the larger the size of the feed particles, the longer the period of their retention in the gizzard. The retention time is particularly important in regulating the rate at which these comes in contact with the digestive enzymes and absorptive surface (Hill and Strachan, 1975).…”