Final answer:
Short-chain fatty acids are the metabolic byproducts of intestinal bacteria.
Step-by-step explanation:
The metabolic byproduct of intestinal bacteria is short-chain fatty acids. These bacteria break down undigested food in the large intestine through a process called saccharolytic fermentation, producing short-chain fatty acids like acetic, propionic, and butyric acids. These acids are an important energy source for the host.