Sites of organic acid production and pattern of digesta movement in the gastrointestinal tract of geese

Relationship of cecal and colonic motility to diet, habitat, and cecal anatomy in several avian species

Previous studies have described several types of contactile activity in the ceca and colon of turkeys. Cecal contractions were termed major and minor; major were propulsive, and minor were presumed to be mixing contractions. Both types propagated either orad or aborad. Colonic contractions were termed long-duration and short-duration, with both types being propulsive. Long-duration contractions were directed aborad; short-duration were directed orad, i.e., antiperistaltic. The latter are believed to be responsible for filling of the ceca from colonic contents and for urinary reflux through the colon. Of eight wild species examined radiographically, there appeared to be little relationship between the cecal size, the nature of colonic antiperistalsis, the type of diet, or the availability of water in the habitat for each species.

Ammonia production from uric acid, urea, and amino acids and its absorption from the ceca of the cockerel

Experiments were conducted in situ and in vitro in the ceca to measure ammonia production from uric acid, urea, and amino acids and its absorption. When uric acid was injected into a cecal sac containing mixed cecal microfloras, 77% disappeared within 1 hour, with a concomitant increase in ammonia concentration. When [15N]uric acid was added to the ceca in situ, 28% was converted to ammonia after 30 minutes. About 92% of the ammonia introduced into a cecal sac disappeared from the lumen fluid within 30 minutes. About 43% of each of urea nitrogen and glutamine-amide nitrogen was converted to ammonia-nitrogen, and 25% of uric acid-nitrogen and epsilon nitrogen of the arginine was found in ammonia. The conversion of aminonitrogen of glutamic acid and glycine to ammonia amounted to 19-20%, whereas that of alpha-alanine totaled 11%. It is concluded that dietary and urinary nitrogenous compounds that find their way into the ceca are useful nitrogen sources for ammonia production by microflora in the ceca of the chicken, and that ammonia is absorbed rapidly from the ceca.

Age influence on digestive transit time of particulate and soluble markers in broiler chickens

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.

Transport function and control in bird caeca

1. The paired caeca at the junction of the ileum and rectum help determine the ionic composition of the voided excreta. 2. The caeca play a role in the transport of water, sodium, potassium, and chloride, the dominant effect being that of sodium transport.

Uric acid and urea in relation to protein catabolism in long-term fasting geese

Five ganders were subjected to an experimental fast comparable to that which spontaneously occurs during breeding in domestic geese, and during migration and breeding in various wild birds. Plasma uric acid and urea concentrations, and their excretion as a proportion of total nitrogen excretion, were studied in relation to daily change in body mass per unit body mass, mg/mdt. This variable has previously been found to reflect changes in protein catabolism over the three phases of fast: I, dm/mdt and protein utilization both decrease; II, they are maintained at a low value; and III, they increase. In the fed state, daily total nitrogen excretion was 5 gN X 24 h-1; uric acid, ammonia and urea accounted for 51, 15 and 5% respectively. The high remaining proportion of excreted nitrogen (29%), after subtraction of uric acid-N, ammonia-N and urea-N to total nitrogen, accords with the literature. During fasting, the changes in daily excretion of uric acid, urea, ammonia and total nitrogen followed a pattern essentially similar to that for dm/mdt. Uric acid accounted for a progressively increasing fraction of total nitrogen, up to 76% at the end of phase III, while urea remained at a constant 5%. Plasma concentrations of both uric acid and urea followed similar trends during the fast, in particular both increasing during phase III, i.e. when there was a rise in nitrogen excretion. This suggests they could be used as an index in field investigations, to determine whether birds which naturally fast in connection with specific activities have entered into the situation where proteins are no longer spared.

Salt and water excretion by birds: the lower intestine as an integrator of renal and intestinal excretion

1. In the fowl, the small intestine is important for net absorption of Ca2+ and K+, but not for Na+ nor water (in this and several other species). 2. Net water absorption in birds with large saccate caeca occurs in caeca greater than rectum greater than coprodeum, but net Na+ absorption (an active process motivating other absorptive functions) occurs in rectum less than caeca and coprodeum. 3. Interspecific variability and the scarcity of comparative studies militate against broad, well-founded generalisations in this subject.

Colonic motility in domestic turkeys

This study was performed to determine (1) if electrical slow waves could be recorded from the colon of turkeys, and (2) how ingesta moves into and through the colon despite colonic antiperistalsis. Electrical activity and contractile forces were monitored via implanted bipolar electrodes and strain gage transducers (SGT), respectively. Two types of slow waves, small (sSW) and large (lSW) were recorded simultaneously. The former were correlated with antiperistaltic contractions observed radiographically and with small contractions recorded with SGT, the latter were correlated with large contractions recorded via SGT. The sSW had higher frequencies distally than proximally while the frequency gradient for the lSW was just the opposite. The sSWs were believed to be involved in regulation of antiperistalsis while the lSW were believed to be involved in regulation of the large contractions which, on the basis of the lSW frequency gradient, appeared to be peristaltic and to be primarily responsible for aborad movement of colonic digesta. The small contractions were believed to be responsible for reflux of urine from the cloaca into the colon and ceca and for cecal filling.

Sites of organic acid production and patterns of digesta movement in the gastrointestinal tract of the rock hyrax

The rock hyrax, smallest of the present day ungulates and a near relative of the elephant, has a gastrointestinal tract of such complex nature that it may be considered ccomparable to both the simple and complex stomach mammals, and also to birds. They have a stomach to body weight capacity equal to that of sheep. But for all its complexity, the passage of ingesta is reasonably rapid. However, there are three major sites of digesta retention and microbial fermentation of the ingested material. The cranial stomach provides the first major site of fermentation with VFA levels comparable to those observed in the rumen (125-145 mM/liter). Quantities of lactic acid are also produced in the foregut where the pH may vary from 2 to 5.5. The ingested particulate material is exclusively retained in the cranial half of the stomach for 4 hours after consumption, and partially retained in the entire stomach for greater than 24 hours. The mid-gut sacculation provides the second major site of fermentation with the retention of the digesta in this gut segment for up to 16 hours. The two ceca provide the third site. Concentrations of VFA in these latter two gut segments approaches 80 mM/liter, while the near stable and neutral pH corresponds to the absence of lactic acid production.