II. Gastrointestinal Tract, Digestive Organs, and Processes

Question 1

Compare and contrast the gastrointestinal tract of a swine to that of a cow.

Answer 1

Swine: Swine have a single-compartment stomach, which means they digest food through simple enzymatic processes similar to humans. They have limited microbial fermentation, so they need more easily digestible feeds.
Cow: Cows have a complex four-compartment stomach (rumen, reticulum, omasum, abomasum) that allows them to digest fibrous plants through extensive microbial fermentation, breaking down tough plant material into usable energy.

Question 2

List the three sections of the small and large intestine.

Answer 2

Small Intestine:
1. Duodenum: The first section, where bile and pancreatic enzymes are secreted to start breaking down food.
2. Jejunum: The middle section, where most nutrient absorption occurs. It’s lined with villi to increase surface area for better absorption.
3. Ileum: The last section, responsible for absorbing any remaining nutrients, including vitamin B12, before food moves to the large intestine.

Large Intestine:
1. Cecum: A pouch that ferments any remaining plant fibers, especially important in herbivores.
2. Colon: Absorbs water, electrolytes, and vitamins produced by gut bacteria, turning digesta into feces.
3. Rectum: The final storage area for feces before it is excreted from the body.

Question 3

The small intestine is the primary site of digestion of several nutrients. What are the special anatomical features of the small intestine helping in this process?

Answer 3

Villi and Microvilli: These tiny, finger-like projections line the small intestine, massively increasing the surface area to allow for maximum nutrient absorption.

Crypts: These are pockets at the base of the villi that produce new cells to replace old ones, ensuring the lining of the intestine remains effective at absorbing nutrients.

Lymph vessels and capillaries: These are found within each villus and help transport absorbed nutrients (like fats and vitamins) into the bloodstream.

Question 4

List the sites of fermentation in foregut fermenting and hindgut fermenting animals.

Answer 4

Foregut Fermenters (e.g., cows, sheep):

Rumen and Reticulum: These are the primary fermentation chambers where microbes break down fibrous plant material into volatile fatty acids that the animal can use for energy.

Hindgut Fermenters:
Cecal fermenters (e.g., rabbits): The cecum is where microbial fermentation occurs, breaking down plant fibers after the small intestine has absorbed most other nutrients.

Colonic fermenters (e.g., horses): The colon serves as the main site for fermentation of plant material, producing energy that the animal can absorb.

Question 5

List the different sections of the foregut in ruminant animals along with their functions.

Answer 5

Reticulum: Acts as a pump that moves small, partially digested food particles from the rumen back to the mouth for further chewing (cud) and fermentation.

Rumen: The largest compartment, where billions of microbes break down fibrous plant material into energy and nutrients that the cow can absorb.

Omasum: This compartment acts as a filter, squeezing out excess water and absorbing minerals, and reducing the particle size of the food.

Abomasum: Known as the “true stomach,” this is where the cow’s digestive enzymes, like pepsin and HCl, begin the process of digesting proteins.