Of the four chambers found in the whitetail’s ruminant stomach, the rumen is by far the largest. The actual size will vary from deer to deer, and the proportional size will be smaller for fawns.
The rumen’s structure itself resembles a large sac or ball and is often referred to as the “paunch.” If you have ever pushed your knife tip too deep when field dressing a deer and cut into a sac that produced a very strong smell and oozed a greenish/brown material, you found the rumen. This large sac creates an oxygen-free environment and is the home of billions of anaerobic microorganisms. These microorganisms ferment ingested food, breaking it down to create digestible nutrients. It is this fermentation that creates the unpleasant smell. The outer layer of the rumen consists of a muscular layer with the purpose of