1. Rumen:
* The largest chamber of the stomach, the rumen, acts as a fermentation vat.
* It houses trillions of bacteria and protozoa that break down cellulose, the main component of plant cell walls, into volatile fatty acids (VFAs) that the deer can absorb as energy.
* Food is regurgitated from the rumen as "cud" and rechewed to further break it down before being swallowed again.
2. Reticulum:
* The reticulum acts as a filter, separating larger particles from smaller ones.
* It also helps move food from the rumen to the omasum.
3. Omasum:
* The omasum is filled with folds that absorb water and nutrients from the partially digested food.
* It also helps further break down food particles.
4. Abomasum:
* The abomasum is the true stomach, where digestive enzymes and acids are secreted to digest the remaining food.
* It's similar to the stomach of other mammals.
5. Small and Large Intestines:
* After the abomasum, the food moves to the small and large intestines, where further digestion and nutrient absorption occur.
Here's a simplified overview:
1. Ingestion: Deer eat a variety of plants, including grasses, leaves, twigs, and fruits.
2. Rumen Fermentation: Food is chewed and swallowed, then fermented by bacteria in the rumen.
3. Cud Chewing: Partially digested food is regurgitated as cud and rechewed.
4. Further Processing: Food passes through the reticulum and omasum, where it's further broken down and water is absorbed.
5. Abomasum Digestion: Food enters the abomasum, where digestive enzymes and acids break down the remaining food.
6. Nutrient Absorption: Digested food passes through the small and large intestines, where nutrients are absorbed.
7. Waste Elimination: Undigested food is excreted as feces.
Key Points:
* The process of rumination allows deer to extract nutrients from tough, fibrous plant matter, making them well-suited to their herbivorous lifestyle.
* The bacteria in the rumen play a crucial role in breaking down cellulose and providing energy to the deer.
* The digestive process can take several hours to complete, and deer spend significant time ruminating.
This process is essential for white-tailed deer to obtain the nutrients they need to survive and thrive in their environment.