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Mechanical action typically in- volves chewing, but since birds do not have teeth other me- chanical methods are used. Chemical action includes the release of digestive enzymes and uids from the stomach, pancreas and liver.
Once the nutrients have been re- leased from food during digestion, they can be absorbed and distrib- uted throughout the animal’s body. e digestive tract is also referred to as the gastro-intestinal or GI tract. Whichever term is used, in birds it begins at the mouth and ends at the cloaca and has several important organs in between (see the Figure 2).