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.

SUMMARYThirty broilers 8-10 weeks old were used to study the rate of food passage in chickens. Wheat bran and rice husks of three different sizes: more than 2 mm, between 1 and 15 mm, and less than 0 5 mm, mordanted with chromium, were used as markers. The suitability ofthese markers to study the rate of food passage in chickens and the possible influence of the size and hardness of the particle on the retention time was the objective of this study. Both T1, the time of first appearance of the marker, and Tm, the mean retention time, have been evaluated. Tm was a better parameter than T1 for studying transit time. Tm was longer with the biggest particles, especially with rice husk. The gizzard, with its grinding activity and pylorus, a selector ofparticle size, seems to be the transit regulator for solid particles in chickens. No chromium was found in the caecal contents of any case.

The gastrointestinal transit-time of two markers, Cr-mordanted bran, a solid marker, and Cr-EDTA, a soluble marker, have been studied in chickens (Gallus gallus) at 1, 2, and 3 wk of age. Mean retention time of the particular marker decreased as chicks grew. The excretion of Cr-EDTA took longer as birds grew; this soluble marker was retained in the ceca of the fowl. It was postulated that the ceca are not fully functional until total resorption of the yolk sac content occurs.

The aims of this work were: A) to define the morphological and functional changes induced by chronic implantation of electrodes for electromyographic studies and B) to study the evolution of the gastrointestinal myoelectrical activity after electrode implantation. Four lots of animals were established: birds implanted with 7 and 5 triplets of electrodes in the gastroduodenal area (lots I5 and I7 respectively); sham operated birds (lot SH) and control (lot C). Body weight was not modified by surgery. Food intake, which was transiently decreased, returned to normal within the first week post-implantation. Gastrointestinal transit time (TT) was significantly increased in lots I7 and SH during the first week. In SH birds TT returned to normal in the second week after surgery, whereas in I7 birds this parameter was not normalized until the third week. Apparent hypertrophy of the duodenum was found in lot I7 but not in lots SH and C (P < 0.05). Qualitative electromyographical changes were found in lot I7 but not in lot I5, with no morphological changes. The evolution of the electrical signal (frequency and amplitude of spiking) was analyzed in lot I5. Frequency stabilized shortly after surgery (0.8-2 days). In contrast, amplitude increased progressively to reach a steady value 9-18 days after surgery. Our results indicate that the number of electrodes implanted for electromyographical studies may induce significant morphological as well as motor changes in the gastrointestinal tract. Thus there should be as few electrodes as possible in order to avoid the changes mentioned above.(ABSTRACT TRUNCATED AT 250 WORDS)

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