Digestive system of body is meant for converting raw food ingredients into metabolizable simpler compounds through action of various enzymes. Consumed food undergoes mastication (mechanical), digestion (enzymatic) and absorption processes in GIT before it is utilized for energy production, body growth and production of milk, egg, wool etc. by the animal. Specific enzymes for breakdown of carbohydrates, proteins, lipids & nucleic acids are produced by various glands and reaction conditions inside organs are maintained through different secretions such as hydrochloric acid in stomach and sodium bicarbonate in ileum. Products of digestion are utilized appropriately by various body organs for their metabolic needs and wastes are excreted out. Enzymatic digestion chiefly occurs in omnivores and carnivores animals whereas microbial fermentation predominates in ruminants and non-ruminants herbivores. Digestion comprises of a rapid, fairly simpler and effective enzymatic breakdown of food whereas fermentation involves much slower, quite complex and less efficient microbial breakdown of dietary ingredients. Domestic animals and poultry show characteristic differences in their digestive tract, digestive process and products of digestion.