Animal ScienceDigestive Systems

Types of Digestive Systems

Cats

Chickens Pigs

DogsTurkeys

Monogastrics Ruminants Hind Gut Fermentors

Beef Cattle Dairy Cattle

Deer

SheepGoats

Horses

Rabbits

Ostrich

Avian

Monogastrics

Cats PigsDogsHumans

• One compartment stomach• Cannot digest grass or hay• Secretes acid and enzymes that

digest food• Need high energy diets

Esophagus

Stomach

Liver Pancreas

Duodenum

Small intestine (jejunum, ileum)

Cecum

Colon

Rectum

Digestive Tract - Pig

Organs of Digestive SystemMonogastrics

Mouth►Mechanical breakdown of foodstuffs by chewing

►Saliva added as a lubricant and begins digestion.

Esophagus►Tube connecting the mouth

to the stomach.

Stomach►Enzymatic digestion of proteins begins.

►Food reduced to liquid form.

Liver►Center of metabolic activity in the body.

►Provides bile salts to small intestine (needed for digestion and absorption of fats).

Organs of Digestive SystemMonogastrics

Pancreas►Provides digestive enzymes to the small intestine to help

in digestion of fats, carbohydrates, and proteins.

Small Intestine►3 sections – duodenum, jejunum, ileum

►Site of final stages of chemical enzymatic digestion.

►Where almost all nutrients are absorbed.

Organs of Digestive SystemMonogastrics

Organs of Digestive SystemMonogastrics

Large Intestine►3 sections – cecum, colon, rectum

►Site of water absorption

►Feces formed.

Avian• Considered monogastric• One compartment stomach• Cannot digest grass or hay• Secretes acid and enzymes

that digest food• Need high energy diets

Chickens

Turkeys

Digestive Tract - Poultry

Esophagus

Crop

Proventriculus

Gizzard Liver

Gall bladder

Cecum

Cloaca

Large intestine

Small intestine (jejunum, ileum)

Pancreas

Duodenum

Organs of Digestive SystemAvian

Beak►No lips, no teeth, and no chewing.

Crop►Pocket of the esophagus that provides storage for

consumed food.

►Food is moistened and softened

Organs of Digestive SystemAvian

Proventriculus►Glandular stomach adds digestive juices

Gizzard►Grinds and breaks up food.

►May contain grit (small stones) eaten by bird.

Organs of Digestive SystemAvian

Cloaca►Common chamber into

which the digestive, urinary, and reproductive tracts open.

Ruminants• Most herbivores• Fore-gut fermentation vat for grass and

hay• Four compartment stomach (not four

stomachs)• Chews cud

Beef Cattle Dairy Cattle DeerSheepGoats

Digestive Tract - Cattle

Esophagus

Rumen

Omasum

Reticulum

Abomasum

Pancreas

Liver

Gall bladder

Cecum

Small intestine

Large intestine

Rectum

Organs of Digestive SystemRuminants

Mouth, esophagus, liver, pancreas, small intestine, and large intestine have functions similar to monogastrics.

Stomach►Multi-compartmented stomach – rumen,

reticulum, omasum, abomasum.

Parts of the Ruminant Stomach

Rumen:►Largest compartment

►“Fermentation Vat”

►Digests forages

Rumen Capacity

Species Normal capacity Maximum capacity

Cow (1000 lb) 25-30 gallons 55-60 gallons

Ewe (150 lb) 3-5 gallons 5-10 gallons

Parts of the Ruminant Stomach

Rumen (continued):

►Lined with millions of

papillae (short projections

on wall of rumen) needed

for absorption. “Shag carpet” appearance

Parts of Ruminant Stomach

Reticulum:

►Contains microorganisms (like the rumen).

►Catches non-digested

material.

►“The Honeycomb”Catches and holds hardware

consumed by animal.

Hardware can be removed with

rumen magnet.

Parts of Ruminant Stomach

Omasum:

►“The Book”

►A heavy, hard organ with a lining that has many folds►Function not well understood.Filters large particles back to

reticulum

Absorbs water

Organs of Digestive SystemMonogastrics

Abomasum:►“True Stomach”

Similar to monogastric or human stomach

►Digests grains and breaks down proteins

Hind-gut Fermenters• One simple, glandular stomach• Hind-gut fermenter (Cecum)

digests plant fiber• Must graze often• Must have fiber (grass or hay)

Horses Rabbits Ostrich

Digestive Tract - Horse

Esophagus

Stomach

Duodenum

Small intestineCecum

Large colon

Small colon

Rectum

Organs of Digestive SystemHind-Gut Fermentors

Mouth, esophagus, stomach, liver, pancreas, and small intestine have similar functions as compared to monogastrics.

Cecum►Large and complex compared to monogastrics and

ruminants.

►Cecum similar to rumen in ruminants

►Fermentation vat

►Microbes to break down fiber

Esophagus

Stomach

Liver Pancreas

Duodenum

Small intestine (jejunum, ileum)

Cecum

Colon

Rectum

Digestive Tract Type?

Digestive Tract Type?

Esophagus

Crop

Proventriculus

Gizzard Liver

Gall bladder

Cecum

Cloaca

Large intestine

Small intestine (jejunum, ileum)

Pancreas

Duodenum

Digestive Tract Type?

Esophagus

Rumen

Omasum

Reticulum

Abomasum

Pancreas

Liver

Gall bladder

Cecum

Small intestine

Large intestine

Rectum

Digestive Tract Type?

Esophagus

Stomach

Duodenum

Small intestineCecum

Large colon

Small colon

Rectum