First compartment of stomach of ruminant is called:

Correct option is D

Rumen – the first and largest compartment where microbial fermentation occurs. It serves as a storage and fermentation vat.

Reticulum – second compartment, works with the rumen in the fermentation process.

Omasum – third compartment, absorbs water and nutrients from digested contents.

Abomasum – fourth compartment, also called the "true stomach," where acidic digestion occurs (similar to monogastric stomachs).

Hence, the first compartment of a ruminant’s stomach is the rumen, which is essential for breaking down fibrous plant material through microbial action.

Why other options are incorrect:

Omasum:

This is the third compartment of the ruminant stomach, known for its leaf-like folds that further process and absorb water from digested material. 

Abomasum:

This is the fourth compartment, considered the "true stomach" as it produces stomach acid and enzymes to digest food. 

Reticulum:

While the reticulum is the second compartment, it's important to note that the rumen is considered the first. The reticulum is primarily responsible for sorting and further breaking down food particles. 

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