What occupies ¾ of the left side of the abdominal cavity in ruminants?

The correct answer identifies the reticulum and rumen as occupying a significant portion of the left side of the abdominal cavity in ruminants. Ruminants, such as cows and sheep, have a specialized digestive system that includes multiple stomach chambers. The rumen is the largest of these chambers and serves as a fermentation vat, where microbial digestion of fibrous plant material occurs. It is essential for breaking down the cellulose found in grasses and other forages.

Alongside the rumen, the reticulum, which is smaller and lies adjacent to the rumen, functions in the separation of particles within the ingested feed and plays a role in rumination or "cud-chewing." Together, both the rumen and reticulum are crucial for the overall digestive process in ruminants, necessitating a substantial amount of space in the abdominal cavity, particularly on the left side.

Understanding the anatomy of a ruminant's digestive system highlights the importance of the rumen and reticulum in terms of not just their physical size but also their vital roles in digestion and nutrient absorption.