The Digestive System

Basic Information

Converts feed into a form that can be used by the body for maintenance, growth and reproduction

Mature light horse: 100 feet long, 40-50 gallons

Stomach makes up less than 10% of total capacity of the digestive track

Mouth

Lips pick up feed and is passed to the mouth by the action of the tongue

Grazing food is grasped by incisor teeth

Food is masticated between molar and cheek and mixed with saliva

Saliva moistens and lubricates the food for swallowing

Food is forced past the soft palate into the pharynx by the base of the tongue

Pharynx

Short, somewhat funnel-shaped, muscular tube between mouth and esophagus

Muscular action forces food into the esophagus

Food or water cannot return to the mouth Due to the traplike action of the soft

palate a horse cannot breathe through their mouth

Esophagus

Muscular tube extending from the pharynx down the left side of the neck and through the thoracic cavity and diaphragm to the stomach

Food forced down by a progressive wave of constriction of the circular muscles of the organ

Food or water through nostrils is almost certain indication that the horse has choked because esophagus has been blocked

Esophagus enters the stomach through an oblique angle, making regurgitation impossible

Stomach

U-shaped, muscular sac in the front part of the abdominal cavity

Food entering is arranged in layers

End next to small intestine fills up first

Contents of the stomach are squeezed and pressed by the muscular activity of the organ

Digestive juice secreted by walls of stomach is known as gastric juice

Small Intestine

Stomach to cecum

Tube that is about 2in in diameter and 70 feet long

Holds about 12 gallons

3 parts

Duodenum

Jejunum

Ileum

Lies in folds and coils near left flank

Large Intestine

Divided into cecum, large colon, small colon, rectum, and anus

Consume large quantities of cellulose in diet

Usual digestive enzymes are not effective against cellulose so horse must rely upon bacteria to break down cellulose into substances it can be absorbed into body

To give bacteria time to act on cellulose, the cecum and the large colon in the horse have been greatly enlarged

Large Intestine

Cecum is elongated sac Contents are always liquid About 4 feet long, 8 gallon capacity

Large Colon Extends from cecum to small colon 12 feet long, 20 gallon capacity Bacterial action and some digestion

of food takes place

Large Intestine

Small Colon 10 feet long

Extends from large colon to rectum

Contents usually solid; here the balls of dung are formed

Moisture in food is reabsorbed here

Rectum 12 inches long

Extends from small colon to anus

Where digestive tract ends

Needs for Feed

Major sources of energy and protein are grain and roughages

Feeding is both an art and a science Require nutrients to maintain body weight and

support digestive and metabolic functions Need additional nutrients for growth, work,

reproduction and lactation Most receive their daily ration in two parts:

roughages and concentrates

Balanced Rations

Balancing rations should: Furnish horses with a daily supply

of nutrition in the correct amounts Supply palatable, easily obtained

feedstuffs Provide feedstuffs economical for

the conditions

Feeds

Four groups Roughages Concentrates Protein Supplements Minerals

Example Ration

Ingredients Pounds to Make ½ Ton Pounds to Make 1 Ton

Oats (crimped or crushed) 440 880

Corn (coarsely cracked) 220 440

Soybean Meal (44%) 240 480

Molasses (liquid) 70 140

Dicalcium phosphate 15 30

Limestone 10 20

Salt (trace mineral) 5 10

Vitamins A, D, E to supply 4000 IU/lb

- -

Total Pounds 1000 2000

Foal Creep Ration: should not be used after weaning because it is too high in protein and calcium unless fed with a nonlegume hay

Calculating Nutrients

Follow these steps:

1. Know what the horse requires

2. Know what kind of feed will fill those requirements economically

3. Know what feeds are palatable

4. Know how much of a given feed the horse can eat

5. Know how to calculate the amount of a nutrient in a feed

Example

What is the protein content of a feed that contains 500lbs of oats, 400lbs of corn and 30lbs of soybean meal

1. Find the protein content of each of the feedstuffs

2. Multiply this value by the number of pounds of the feedstuff into the mixture

3. Next find the total pounds of protein in the feed mixture

4. Finally, divide the total amount protein in the feed mixture by the total weight of the feed mixture and convert to a percentage

Feedstuff Protein Pounds in MixProtein in Mix

Oats 0.118lb/lb x 500= 59lbs

Corn 0.091lb/lb x 400= 36lbs

Soybean Meal 0.445lb/lb x 30 =13lbs

Total 930108lbs

108lbs of protein in mixx 100 = 11.6percent protein930lbs of feed mix