Final answer:
The ruminant digestive system, exemplified by goats, includes a four-chamber stomach with specialized functions that allow for the breakdown of cellulose in plant material. Microorganisms in the rumen ferment the food, which is later regurgitated as cud for further chewing before water removal in the omasum and enzymatic digestion in the abomasum.
Step-by-step explanation:
Ruminant animals such as goats have specialized digestive systems to handle and digest large amounts of plant material. Unlike pseudo-ruminants like camels and alpacas, which have a three-chamber stomach, ruminants possess a four-chamber stomach: the rumen, reticulum, omasum, and abomasum.
The digestion process begins with the animal tearing and chewing plant material, facilitated by their lower teeth, tongue, and lips since they lack upper incisors.
After being swallowed, the food passes through the esophagus to the rumen, where it is fermented by a complex microbiota that can break down cellulose. This partly digested food, known as cud, is then regurgitated from the reticulum back to the mouth for further chewing.
Once the cud is chewed again, it travels down to the omasum, where water is removed, and then to the abomasum, the equivalent of the human stomach, where digestive enzymes continue to process it. Finally, the digested material passes into the small and large intestines for nutrient absorption and water recycling, with waste products being excreted.