Which ruminant stomach compartment is often referred to as the "true stomach"?

The abomasum is referred to as the "true stomach" in ruminants because it is the compartment that functions similarly to the single-chambered stomachs found in non-ruminant animals. It is responsible for the secretion of gastric juices, such as hydrochloric acid and digestive enzymes, which are crucial for the chemical digestion of food. This process is significantly different from that of the other compartments, including the rumen, reticulum, and omasum, which primarily serve as fermentation chambers or involve the uptake of water and nutrients rather than the digestion of food in the same manner as non-ruminants.

The rumen is the largest stomach compartment, playing a key role in fermentation and microbial digestion but does not perform enzymatic digestion. The reticulum is tasked with sorting feed particles and is involved in the regurgitation process, facilitating rumination. The omasum's primary function is to remove excess water from the digestive contents. While all these compartments are critical for overall digestion in ruminants, it is the abomasum that is distinctly recognized for its role in chemical digestion, aligning it with the function of a "true stomach."