Even though pig feed is ground, it must still be broken down into even smaller molecules in order to be absorbed from the digestive tract. For example, proteins must be broken down into amino acids and starch must be broken down into glucose. The digestion of feed in the pig is achieved through the use of enzymes that the pig naturally secretes from its stomach, pancreas and small intestine. However, the pig's array of enzymes is not capable of breaking down all components of its diet. Since the pig is unable to fully utilize all components of its diet, specific enzymes can be added to the feed to help break down complex carbohydrates, protein and phytate. These enzymes are called carbohydrases, proteases, and phytases, respectively. They are derived from bacteria and yeasts. At the time of writing, almost 200 different enzymes and enzyme products were available worldwide to the pork industry.