Which of the following is NOT classified as a ruminant animal?

To determine which animal is not classified as a ruminant, it is essential to understand the defining characteristics of ruminants. Ruminants are a specific group of mammals that have a specialized stomach with four compartments: the rumen, reticulum, omasum, and abomasum. This unique stomach structure allows these animals to efficiently digest fibrous plant material through a process called rumination, where they regurgitate food to chew it again.

Sheep, cows, and goats are all examples of ruminants. They possess the four-chambered stomach that aids in their ability to break down complex carbohydrates and extract nutrients from tough plant materials. Their digestive process includes multiple steps, which involve fermentation and microbial action.

Pigs, on the other hand, are classified as monogastric animals, meaning they have a single-chambered stomach. Their digestive systems are better suited for processing a more omnivorous diet that can include meat, grains, and vegetables but do not include the four-chambered stomach structure seen in ruminants. Thus, pigs do not undergo rumination and are not considered part of the ruminant classification, making them the correct answer to the question.