Digestive Tract and Digestion

Digestive Tract and Digestion

A function of the digestive tract is to assimilate compounds in grain (water, protein, oil, carbohydrate, and ash) into pork and poultry products for human consumption. It is apparent that the digestive track serves an important role in agriculture considering how the composition of grain and that of a market pig contrast (Figure 2). Carbohydrate, the most abundant constituent in grain, is practically nonexistent in the body of a market pig. Instead starch and fiber, which comprise the carbohydrate fraction of grain, are metabolized into glucose and volatile fatty acids, respectively.

These compounds yield calories. The amount of fat and water in the body is significantly higher than that in corn grain. The oil in grain is used as a source of calories too, but it is not responsible for the majority of fat in the carcass. Instead, glucose is used to manufacture the majority of the fat in the carcass. Although the protein content of corn grain and that of a pig’s body is similar, the amino acid contents are considerably different. During digestion, proteins in corn are hydrolyzed into amino acids and reorganized into different proteins in the animal’s body.

Fig. 2 The relative composition of corn grain and a 220 lb. pig.

See the animation to examine the digestive tract and digestion in swine and poultry.