A veterinarian with decades of experience, A. Morrie Craig simultaneously utilized his prior knowledge of biophysics in his research. By studying how animals with a ruminal digestion system processed feed at sites near a local military base, Dr. A. Morrie Craig found microorganisms in the animals which allowed them to feed there without incurring harm from toxins in the environment.

The ruminal digestive system consists of four parts: the rumen itself, the reticulum, omasum, and obomasum. A cow’s rumen consists of one large sac, subdivided into smaller ones, where it initially stores food. The reticulum stores heavier feed, and the omasum absorbs water from digested material. The obomasum acts like a human stomach, by releasing hydrochloric acid to break down foods.

The ruminary digestive system also contains many bacteria and fungi which break down food besides the obomasum. The types within depend on an individual cow’s diet, with more complex diets leading to more biodiversity. Because a cow’s rumen shelters bacterial cultures over time, adults can digest certain compounds, and feed types containing them, better than calves.