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THE DIGESTIVE SYSTEM OF
VERTEBRATES
BIRDS: Ptarmigan
Willow ptarmigan (photo by Dr Cheri Gratto-Trevor) (from CD Chapter 2)
Table 7.3. Mean digesta retention time in birds (from CD Chapter 7)
Digesta transit time of birds tend to be short, and particles are generally retained longer than fluid digesta, but fluid was selectively retained in the ceca of the herbivorous ptarmigan. (From Stevens and Hume 1995)
Table 7.5. Mean digesta retention time for herbivorous cecum fermenters (from CD Chapter 7)
Although digesta retention times are affected by differences in the diet, and in the body temperatures of the bird, marsupials, and eutherian mammals, cecum fermenters retain fluid digesta as long or longer than particulate digesta. Fluid and small digesta particles are selectively retained by the cecum of small mammals with a large cecum, especially in herbivores with a well-developed colonic separation mechanism. The longer digesta retention times of the marsupials are due, partly, to their lower rate of metabolism. (modified from Stevens and Hume 1995)
Table 9.7b. (from CD Chapter 9)
* Absorption from cecum (or ceca) alone.
Dashes indicate absence of information. Contributions of SCFA to maintenance energy were estimated from the rate of SCFA production by in vitro isotope dilution or measurements of digesta flow. Total maintenance energy was either calculated as twice the BMR or assumed to be equivalent to ad libitum digestible energy intake in captive, nonreproducing, and adult animals. (From Stevens and Hume 1995)