The effect of corn-canola meal and corn-soybean meal diets on the form and function of the gastrointestinal tract of broiler (meat-type) and White Leghorn (egg-type) cockerels was measured from 14 to 44 and 14 to 86 days of age or 203 to 1,844 and 115 to 1,777 g of body weight, respectively. Dry weights of the empty crop (P less than .01), gizzard (P less than .001), and ceca (P less than .001) relative to live body weight (g/kg) were lighter in broilers than in Leghorns. Canola meal at 370 g/kg diet was associated with increased (P less than .001) dry weight of the gizzard and jejunum relative to body weight. Soybean meal at 370 g/kg diet was associated with increased (P less than .001) dry weight of the ceca relative to body weight. The lengths, relative to a power of body weight of the duodenum (cm/g.187) and jejunum plus ileum (cm/g.240), were longer (P less than .001) in broilers than in Leghorns. The canola meal diet was associated with an increase (P less than .001) in length of the jejunum plus ileum (cm/g.240) relative to a power of body weight. Mean retention time (MRT) of a particle marker, 103ruthenium phenanthroline, increased with body weight in the entire gastrointestinal tract (P less than .001) and in each of its segments except in the proventriculus, where it was not affected by body weight (P greater than .05), and in the gizzard, where it decreased (P less than .05) with body weight. The MRT, adjusted for body weight in the entire gastrointestinal tract of broilers (338.0 +/- 10.8 min) and Leghorns (359.9 +/- 10.8 min), was similar (P greater than .05) but varied significantly in segments of the gut for both type of chicken and diet. Adjusted MRT was shorter in the crop (P less than .001) and gizzard (P less than .001) and longer in the duodenum (P less than .001) and ileum (P less than .01) of broilers than Leghorns. The soybean meal diet was retained for 2.3 min longer in the duodenum (P less than .001) and 84.2 min longer in the ceca (P less than .001) than the canola meal diet, which accounted for the longer (P less than .001) retention of the soybean meal diet in the entire gastrointestinal tract (388.0 +/- 10.6 vs. 309.8 +/- 10.8 min). Segments of the gastrointestinal tract vary in length, weight, and MRT of digesta with dietary composition and type and body weight of chicken.

A variety of factors influence the voluntary intake of ruminants including reticulo-rumen fill or distension (Campling & Balch, 1961; Welch, 1967; Grovum, 1979) and rate of passage of digesta through the gastrointestinal tract (Bines & Davey, 1970). The exit point of the reticulo-rumen, the reticulo-omasal orifice, potentially serves as a control site in regulation of particle movement from the rumen.However, little definitive information on the functional behaviour of this anatomical location is available. Therefore, a fibre-optic endoscopic technique was designed to allow visual observation of the reticulo-omasal orifice in conscious, fed cattle.America, New Hyde Park, NY) and a 35 mm camera (Olympus 0M-2N with 1–9 focusing screen) was attached. Photographs were taken at a shutter speed of 1/30 or 1/60 sec. The film used was Kodak (ASA 160) tungsten balanced slide film. Prints were generated from slides using the Cibachrome P30 process. An Olympus CLK-3 cold light source, having a colour temperature of 3200 °K, provided the illumination for projection through the endoscope. Opening and closing of the reticuloomasal orifice were photographed using this procedure.

Digesta transfer from the reticulo-rumen to the omasum of a fed steer was filmed in situ using fiberoptic techniques. The reticulo-omasal orifice was not a site of discrimination of the size of digesta particles that leave the rumen. Large particles (10 mm in length) could clearly pass through the orifice.Key words: Reticulo-omasal orifice, digesta transfer, cattle Movement of contents from the rumen is not indiscriminate, since the average size of digesta particles posterior to the rumen (Reid et al. 197'7) or in feces (Poppi et al. 1980) is distinctly less than that in the rumen. The reticulo-omasal orifice has often been assumed to regulate particle exit to the rest of the ruminant digestive tract (Welch 1982

No abstract

An instrumental neutron activation analysis (INAA) method has been devised which permits rapid and reliable analysis of the liquid phase markers Cr-EDTA and Co-EDTA. Dried rumen fluid samples, containing Cr-EDTA and Co-EDTA, were irradiated in the Slowpoke reactor. The analytical scheme previously devised for solid phase marker l'j5mDy determination was found to provide an acceptable compromise between sensitivity and sample throughput (45 samples h-l) for the short-lived 'jnmCo (Tl/2= 10.47 min). Cr measurements required longer irradiation cooling and counting times. To permit satisfactory sample throughput, batch sample irradiations and an automated NaT(T1) scintillation detector was used. Gamma interferences were studied with a high resolution Ge(Li) detector and found to be negligible provided that sufficient decay time is allowed. Detection limits for Co and Cr are presented for the analytical schemes used.