1 Comparative Digestive Physiology (mod) 大学动物营养学课件 英文版.pptVIP

Esophagus * True stomach (secretion of HCl and pepsin) Colugos are 2-4 pounds in weight and believed by some scientists to be the closest living relatives to primates. Formerly believed to be related to bats, They have a specialized skin fold, called patagium, stretches from neck to forelimbs, to hindlimbs, and finally to tail. They are natives of southeast Asia and can glide 200 to 250 feet with almost no loss of altitude. Advantages of Pregastric Fermentation Make better use of alternative nutrients Cellulose Nonprotein nitrogen Ability to detoxify some poisonous compounds Oxalates, cyanide, alkaloids More effective use of fermentation end-products Volatile fatty acids, microbial protein, B vitamins Allows wild animals to eat and run Disadvantages of Pregastric Fermentation Fermentation is inefficient Energy Loss % of total caloric value Methane 5-8 Heat of fermentation 5-6 Relative efficiency is dependent on the diet NDF Protein Some ammonia resulting from microbial degradation will be absorbed and excreted 20% of the nitrogen in microbes is in the form of nucleic acids Disadvantages of Pregastric Fermentation Ruminants are susceptible to ketosis Ruminants are susceptible to toxins produced by rumen microbes Nitrates to nitrites Urea to ammonia Nonstructural carbohydrates to lactic acid Tryptophan to 3-methyl indole Isoflavonoid estrogens to estrogen coumestans Pregastric Fermenters Class Species Dietary habit Ruminants Cattle, sheep Deer, antelope, camel Grazing herbivores Selective herbivores, including folivores and frugivores Nonruminants Colobine monkey, hamster, vole Kangaroo, hippo Hoatzin Selective herbivores Grazing and selective herbivores Folivore Postgastric Fermentors Cecal fermentors Mainly rodents, rabbits and other small herbivores Often associated with coprophagy Colonic fermentors Includes true herbivores (e.g., horse), omnivores (e.g., pig and human), and carnivores (e.g., cat and