The avian cecum: Update and motility review

Abstract

The ceca, intestinal outpocketings of the gut, are described, classified by types, and their occurrence surveyed across the Order Aves. Correlation between cecal size and systematic position is weak except among closely related species. With many exceptions, herbivores and omnivores tend to have large ceca, insectivores and carnivores are variable, and piscivores and graminivores have small ceca. Although important progress has been made in recent years, especially through the use of wild birds under natural (or quasi-natural) conditions rather than studying domestic species in captivity, much remains to be learned about cecal functioning. Research on periodic changes in galliform and anseriform cecal size in response to dietary alterations is discussed. Studies demonstrating cellulose digestion and fermentation in ceca, and their utilization and absorption of water, nitrogenous compounds, and other nutrients are reviewed. We also note disease-causing organisms that may be found in ceca. The avian cecum is a multi-purpose organ, with the potential to act in many different ways-and depending on the species involved, its cecal morphology, and ecological conditions, cecal functioning can be efficient and vitally important to a bird' s physiology, especially during periods of stress.

GUT IMMUNITY IN BIRDS: FACTS AND REFLECTIONS (review)

“…This assumption was indirectly evidenced by retrograde (backward) intestinal contraction in birds. In the authors' view, such retrograde motility of the middle intestine improves reabsorption of urine and caecal contents, and provides better absorption of cellulose degradation products and crude protein (82)(83)(84). Such reverse peristalsis between the middle part of jejunum, duodenum, and even gizzard, was observed in both newly hatched chicks and in adult chickens (85).…”

Discrimination Factors for Stable Isotopes of Carbon and Nitrogen in Blood and Feathers from Chicks and Juveniles of the California Condor

“…Unfortunately, these studies analyzed whole blood only, so we cannot compare our values for plasma or RbCs with those from other large carnivorous birds. Therrien et al (2011) speculated that the owls they studied may have had Δ 15 N values lower than those of the falcons because of owls' better-developed cecum (Clench andMathias 1995, Clench 1999) and the potential for different rates of nitrogen assimilation and excretion in birds with ceca of varying sizes. Vultures have the same small or vestigial ceca as members of the order Falconiformes (Clench 1999), so the lower Δ 15 N values observed in our condors cannot be attributed to differences between condors and falcons in the size of the ceca.…”

Cecal drop reflects the chickens' cecal microbiome, fecal drop does not

“…This is in contradiction to the concentrations of the facultative anaerobic bacteria found in fecal drop, being four to seventy times higher compared to that found in cecal content. This could be explained by the longer storage of the feces in the cloaca and by the stickier content of the cecal drop compared to fecal drop, which makes it much more difficult for oxygen to penetrate (Lombardo et al, 1996;Clench, 1999). The concentrations of the strict anaerobic bacteria, Ruminococcaceae, Lachnospiraceae, Alistipes, Bacteroides and Clostridiales in cecal content compared to cecal drop were very similar.…”

“…Several times a day the ceca contract, pushing their content in two directions: towards the ileum and towards the cloaca, excreting a cecal drop (Herrick and Edgar, 1947;Clench, 1999;Janssen et al, 2009). The ceca fill again by use of peristaltic and antiperistaltic contractions at their entrances (Fenna and Boag, 1974).…”