1. EQ Sci II – Digestive System
Obj. 3.01

2. Digestive System
The parts of the digestive system work together to convert feed into a form that can be used by the body for maintenance, growth, and reproduction. Parts include the mouth, pharynx, esophagus, stomach, intestines, anus, and associated organs like the liver, teeth, pancreas, and salivary glands

3. Digestive System
Rate of feed passage through the stomach (30 minutes to 2 hours) and small intestine is very rapid so that any feed not digested and absorbed in the small intestine passes on to the cecum and colon within 2 to 4 hours.
Grinding or chopping decreases feed size which increases the rate of passage but decreases the absorption of nutrients by equine.
It is easy to overwhelm the digestive capacity of the equine’s stomach and small intestine with large amounts of concentrates, which if they pass through to the cecum, becomes fermented and produce gas or lactic acid causing colic or founder.

4. Digestive System
Mouth: Extends from the lips to the pharynx. It is bounded on the sides by the cheeks, above by the hard palate, and below by the tongue.

5. Digestive System
Pharynx: The muscular, somewhat funnel shaped tube from the back part of the mouth to the esophagus that directs food and serves as an air passage.
Esophagus: Extends from the pharynx down the left side of the neck through the thoracic cavity and diaphragm to the stomach at an angle which makes regurgitation possible.
Stomach: A U-shaped muscular sac at the front of the abdominal cavity close to the diaphragm and makes up less than 10% of the total digestive capacity for an adult equine.

6. Digestive System
Small Intestine: A tube about 2” in diameter and is the site of most nutrient absorption but makes up only 30% of the total digestive capacity.

7. Digestive System
Large Intestine: Consists of the cecum, large colon, small colon, rectum, and anus
The cecum and colon make up 65% of the digestive system capacity and are greatly enlarged to allow bacteria time to break down the large quantities of cellulose from plant material
The small colon extends from the large colon to the rectum and is the place where the balls of dung are formed. The contents are solid as most of the moisture in the food is reabsorbed in this part of the large intestine.

8. Digestion Video
Click on the following link to watch a short video on equine digestion…

9. Your Assignment…
Using the paint on the back table, please create a model of the equine digestive system. Trace the outline of a horse on a sheet of pink paper and then create your digestive tract.
Make sure to label all parts of the system like the example on the right
Let me know if you have questions.

10. Example