Why is a cow more efficient at utilizing rough forage crops than humans?

It all comes down to differences in digestive systems. Humans have a monogastric digestive system, designed to break down proteins and starches from bread and meat and other protein sources. Meat takes longer to break down but is broken down more efficiently than plants, which only stay in our stomach for so long before, being unable to have any more nutrients extracted from the fibrous material, is passed through much faster than the protein-based food.

Cows, on the other hand, have a stomach with four large chambers that are designed to break down fibre and use it to their bodily needs. The rumen, reticulum, omasum and abomasum all have an important role in breaking down tough, fibrous material that would simply pass through a human's digestive system as feces.