Transcript Digestion

Digestion
The process of
breaking down
feeds so the
body can use
them
Four steps in digestion
1. Obtaining food and taking into
the body
2. Breaking food down
3. Absorbing nutrients
4. Elimination of undigested wastes
Obtaining Food
Animals use their SENSES to find FOOD.
Food is taken in through the MOUTH.
This is called INGESTION.
Amount of Food Ingested
is determined by:
Hunger -- the intrinsic desire for food,
regardless of food type or preference
Appetite -- the specific type of food that
is preferentially sought.
What Animals Eat
Herbivore -- majority of diet comes from
plant products
Examples -- Cow, Sheep, Goat, Horse, Rabbit
Carnivore -- majority of diet comes from
animal products
Examples -- Dog
Omnivore -- eats both plant and animal
products
Examples -- Humans, Pigs, Poultry, Mouse
Breaking Food Down
Food is broken down in two ways:
1. CHEMICAL -- the use of chemical
substances (ENZYMES) to dissolve the
food.
2. MECHANICAL -- the use of
PHYSICAL structures (chewing,
grinding) to break the food apart.
Food is broken down in the
following structures:
Mouth -- MASTICATION -- grinding or
chewing of food
SALIVA--watery liquid in mouth that
begins dissolving the food.
Mastication -- Teeth
Incisors -- cutting and food intake action
55 psi
Canines -- ripping and biting (Carnivores
and Omnivores only)
Premolars -- grinding action
Molars -- grinding action
200 psi
Esophagus
the muscular tube connecting the
MOUTH with the STOMACH
PERISTALSIS -- the movement of food
through the digestive system by a series
of muscular contractions
Analward Peristaltic Movements
Stomach
Compartment used for digestion and
storage
Cattle and sheep (RUMINANTS) have 4
compartments
Horses and swine (NONRUMINANTS)
have 1 compartment
Absorbing Nutrients
Nutrients leave the digestive tract and
enter the blood so they can be used by
every cell
Small Intestine
most of the food nutrients are absorbed
into the blood here
The small intestine is very LONG and
contains many small folds called VILLI
which increase the surface area for more
absorption.
Three parts
Duodenum, Jejunum, Illeum
Large Intestine
Water is absorbed into the blood and
undigested wastes prepare to leave the
body
Removal of Undigested
Wastes
Not all of the food eaten can be digested
and absorbed.
After most of the water is absorbed,
waste is removed from the body through
the anus or vent.
Other organs that assist in
digestion
liver -- stores carbohydrates
(glycogen), detoxifies blood,
produces bile
pancreas -- produces insulin and
pancreatic juice
gall bladder -- stores bile until it is
needed
Terminology of feed as it
moves through the system
Feed or Feedstuff
Ingesta
Cud
Chyme
Digestive End Products (DEP’s)
Fecal Material or Non-Digested End
Products
Feces
The GI tract -- Descending
Oral cavity (mouth)
Incisors
Molars
Esophagus
Stomach
1 compartment, or
4 compartments
Small Intestine
Duodenum
Jejunum
Illeum
Cecum
Large Intestine
Rectum
Anus
(Colon)
Enzymes and Chemicals
Name of Enzyme
Amylase
Type of food broken down
What the food Becomes
Starch (carbohydrates)
Disaccarides (carbohydrates)
Lipids (fats)
Fatty acids
Maltase
Maltose (carbohydrates)
Glucose
Lactase
Lactose (carbohydrates)
glucose and galactose
Pepsin
Protein
peptides
Peptidase
peptides
amino acids
Trypsin
protein
peptides
Sucrase
sucrose
glucose and fructose
Lipase
Name of Chemical
Gastric Juice
Where Produced
Enzymes Contained
Lining of the stomach
hydrochloric acid, pepsin
Liver (stored in gall bladder)
Lipase
Pancreatic Juice
Pancreas
Lipase, trypsin, amylase
Intestinal Juice
Lining of the small intestine
Sucrase, Maltase, Peptidase, Lactase
Bile
Ruminant Digestive
System
 Cattle and sheep have a RUMINANT
digestive system.
This means that their stomachs have
FOUR compartments.
The first of these compartments contains
many MICROORGANISMS that help
break down CELLULOSE.
Ruminant Digestive
System
 Cellulose -- a substance found in the
cell walls of plants. It cannot be used
unless it is first broken down fermented)
by microorganisms.
Ruminant Digestive
System
Two types of Microorganisms
Bacteria -- digest and ferment readily
available carbohydrates; digest and
ferment the cellulose and
hemicellulose part of feed.
Protozoa -- store readily available
carbohydrates; produce protein;
ferment cellulose material
Ruminant Digestive
System
Regurgitation -- ruminants consume
large amounts of roughage. It is first
chewed just enough to swallow it.
After they consume the food, they
REGURGITATE it, or force it back into
the mouth, so that it can be chewed
again. (Chewing CUD).
Ruminant Digestive
System
4 parts of a ruminant stomach
Rumen -- the largest compartment; stores and
ferments the feed
Reticulum -- foreign particles (nails, wire) are
removed
Omasum -- eliminates water from the feed
Abomasum (true stomach) -- gastric juice is
secreted;feed is broken down
Ruminant Digestive
System
Monogastric Digestive
System
Monogastric Digestive System
Swine, dogs, bears and humans have only
one stomach. These animals cannot
digest cellulose.
Monogastric Digestive
System
Modified Monogastric
System
Modified Monogastric System
Horses and rabbits have only one
stomach, but have structures that contain
microorganisms so they can digest
cellulose.
Microorganisms are found in the cecum
and in the large intestine.
Modified Monogastric
System
Avian Digestive System
Birds (Turkeys, Chickens and pigeons)
have structures not found in other
species that allow them to digest shells
of seeds and other hard foods.
Avian Digestive System
Crop -- a storage organ that holds food
until it can be digested
Gizzard -- grinds the food
Cloaca -- the cavity just before the vent
that collects undigested wastes, uric
acid (instead of urine -- high in
nitrogen), and reproductive cells.
Avian Digestive System