Fiber is fermented in the pig's large intestine, specifically in the cecum and colon. The cecum is a pouch-like organ located at the junction of the small and large intestines, while the colon is the longest portion of the large intestine. These regions are home to a diverse community of microorganisms, including bacteria, protozoa, fungi, and methanogens, which break down the complex plant fibers into simpler molecules, such as volatile fatty acids (VFAs), that the pig can absorb and use as an energy source.