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=== Comparative ===

=== Comparative ===

The natural diets of different animal species largely govern the structure and function of the gastrointestinal tract.   

The natural diets of different animal species largely govern the structure and function of the gastrointestinal tract.   

Broadly, animals can be classified as carnivores, herbivores or omnivores according to diet.  Digestion and absorption of nutrients in carnivorous animals such as the dog and cat takes place largely in the small intestine.  Because only minimal fermentation is necessary for carnivores, they have a minimally developed caecum in comparison to  nonruminating herbivores such as the horse.  The pig, an omnivorous animal has both a relatively long small intestine and an expanded portion of the colon that aids in fermentation of the fibrous material in the diet.  The following figures illustrate the differences between the gastrointestinal tracts of the main domestic animal species (Reece, 2005). [Figures!!]   

Broadly, animals can be classified as carnivores, herbivores or omnivores according to diet.  Digestion and absorption of nutrients in carnivorous animals such as the dog and cat takes place largely in the small intestine.  Because only a samll amount of fermentation occurs in the large intestine of carnivores, they have a minimally developed caecum in comparison to  nonruminating herbivores such as the horse which reies heavily on the end products of microbial digestion that occur in the large intestine.  The pig, an omnivorous animal has both a relatively long small intestine and an expanded portion of the colon that aids in fermentation of the fibrous material in the diet. Ruminants are an exception as fermentation largely occurs in the stomach.  The following figures illustrate the differences between the gastrointestinal tracts of the main domestic animal species (Reece, 2005). [Figures!!]   

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