Your Horses Digestive Tract Utah State University ADVS

Your Horse’s Digestive Tract Utah State University ADVS 2190

Purpose of the Digestive Tract l Convert feed into usable energy l Not simple stomached or ruminant Combination of both l Hind-gut fermenter l

The horse’s digestive tract Herbivore l Small amounts of food passing through constantly. l l l ~100 ft long ~40 -50 gallons

Fore gut and Hind gut Fore gut l Lips l Mouth l Pharynx l Esophagus l Stomach l Small Intestine l Hind gut l Cecum l Large colon l Small Colon l Rectum l Anus l

Foregut l Responsible for Obtaining and grinding food into easily digestible pieces l Concentrate digestion and absorption l l NO FORAGE DIGESTION

Let’s start at the beginning l Lips l Mouth l Teeth l l Used to ? Saliva Lubrication l Starch > Simple sugars l How much saliva ? l

Mouth to Esophagus l Pharynx Helps guide food into the esophagus l Muscular tube ~4 -5 inches long l l Epiglottis Muscular flap that closes over the top of the trachea l Prevents food from going into the lungs l

Esophagus l Soft tube- pharynx to stomach l Different from trachea l Located where ? l Peristaltic muscular contractions + cardiac sphincter at esophagus/stomach juncture l Means a horse cannot …….

Your Horse’s Stomach Makes up 8% of digestive tract l Holds 3 – 5 gallons l l J shaped Food in stomach only short time l Breakdown of some nutrients into intermediate components l

Horse Stomach l Divided into two sections l Non-glandular l l Sensitive to acids Glandular l Protected from acids

4 Subdivisions of the Stomach Esophageal l No digestive glands l holding area for food l Cardiac l Closest to heart l Produces mucus to protect stomach l Fundic l Main body of stomach l Fundic and Gastric glands (produce enzymes, hydrochloric acid, and mucus ) l Pyloric glands, secrete mucus and small amounts pepsin l

Equine Stomach continued … l Gastric Juice produced 2. 5 -8 gallons daily l Contains mucus, pepsin, hydrochloric acid l Continuous – increases when food is present l l l Problem ? Chyme l Resulting food material leaving the stomach via pyloric sphincter

The Small Intestine l 30% of digestive tract l 65 -88 ft l long Site of breakdown and absorption l Carbohydrates l Proteins l Fats l Vitamins/Minerals

Small intestine –subdivisions l Duodenum ~3 ft l Pancreas l Liver l l Jejunum l ~65 ft l Ileum l ~5 ft

Assistants to the SI l Liver l Pancreas

Your Horse’s Large Intestine l ~60% of digestive tract l Cecum l Colon l Large colon l Small colon l Rectum Hindgut digestion of forage

Hind gut fermentation l Digests complex insoluble carbohydrates Horse alone cannot break down l Fiber l l Micro-organisms breakdown insoluble carbs via Fermentation l More than ten times number of micro-organisms in digestive tract than tissue cells in horses body

Cecum l l l 4’ long, 8 gallons Blind pouch Fermentation vat l l Bacteria, fungi, & protozoa Digestion of fiber l Water absorption l Why is a horse less efficient at digestion ?

Large Colon l l l 12’ long, 20 gallons 48 -65 hrs Absorption site for products of cecum Water Absorption 4 sections 3 flexures

Parts of the Large Colon l Right l Sternal Flexure l Left l Ventral Pelvic Flexure l Left l Ventral Dorsal Diaphragmatic flexure l Right Dorsal

View from the Top A = ileum B = cecum C = right ventral colon C. 5 = sternal flexure D= left ventral colon E= pelvic flexure F = left dorsal colon F. 5 = diaphragmatic flexure G = right dorsal colon H = transverse colon I = small colon

Small Colon l 10 -13 ft l in length Narrower than the large colon l Water absorption l Formation of fecal balls l Coated with mucus l Pass through rectum

Rectum l ~12 inches long l Still part of the colon l Short straight tube l Primarily a holding area for fecal matter. l Leads to the anus l Anus l l Sphincter that prevents fecal matter from continually dropping out of the digestive tract. Also prevents matter from entering the hind end of the digestive tract.

Digestive System review