The Equine Digestive System Presentation Part 2: Anatomy of the Digestive System #8895-A

Mouth First section of alimentary canal Contains 24 molars and 12 incisors Includes tongue and salivary glands

Mouth Prehension -the grasping and moving of feed into the mouth by a sensitive, mobile upper lip Precise - can graze grass almost into ground Sorts and selects hay

Mouth Digestion - begins in mouth when feed is masticated by the teeth – grinded and chewed by the mouth Serves to reduce feed particle size

Mouth Saliva: 85 pounds (10 gallons) daily Wets feed - Easier to pass through esophagus Enzymes - help digest carbohydrates Produce large amounts only while chewing

Pharynx Muscular Funnel shape Guides feed into esophagus Located in upper back of mouth where digestive and respiratory tracts cross

Pharynx Once feed or water enters pharynx, it cannot return because of blocking action of soft palate Epiglottis closes at the same time to prevent feed from entering lungs

Esophagus 4 to 5 feet in length Extends from mouth down left side of neck, through the diaphragm, and to the stomach Moves feed and water to stomach by progressive waves of muscular contractions called peristalsis

Esophagus Waves irreversible Extreme muscle tone occurs at end of esophagus

Esophagus Extremely difficult to expel gases through eructation – the act of expelling gas from the stomach through the mouth Stomach would rupture before vomiting would occur

Stomach U-shaped sac near diaphragm at front of abdominal cavity Sphincter acts as powerful muscle where esophagus enters into stomach Makes vomiting nearly impossible

Stomach Small compared to other animals 10% of total capacity of entire digestive tract Capacity - two to four gallons – requires they eat two to three times daily rather than just once

Stomach Feed moves through rapidly Frequent feeding in small amounts is more efficient and better satisfies Rate of passage is rapid in comparison to other areas – Time required for something to move through an area

Stomach Reservoir for ingested feed while subjecting it to gastric digestion – chemical breakdown of feedstuffs by the stomach Gastric juices, secreted by glands in the mucous membrane of stomach, contain hydrochloric acid, pepsin & gastric lipase

Stomach Pepsin is a protease - enzyme that helps digest protein into amino acids – building blocks of proteins Gastric lipase - digest fat into fatty acids & glycerol

Stomach When two-thirds full, feed passes into small intestine and continues as eating continues If horse eats too much at one time, some will leave stomach without sufficient digestive action – Leads to decreased efficiency

Stomach Number of digestive disorders can occur Caused by: – moldy feeds – ground mashes – sudden changes in feed – feast-and-famine situations – parasites

Stomach Very little nutrient absorption takes place in the stomach Proteins and carbohydrates are only partially digested