A pig's small intestine measures about 12 feet long. The large intestine measures from 1 to 3 feet. Omnivores generally have longer intestines than carnivores.
The small intestine is a long, spiraled tube designed to fit a small space. The first section of the small intestine is called the duodenum. This is where the secretions from the pancreas and liver are added. As digestion continues, nutrients are absorbed in the jejunum and the ileum.
Any undigested nutrients pass through to the large intestine through the ileocecal valve. The large intestine has the main function of absorbing water and some final digestion. Any undigested food leaves the large intestine through the rectum to the anus.