Livestock Nutrition
Ch. 2
Digestion in Animals
Objectives
1- Describe the nonruminant
(monogastric), ruminant, and avian
digestive systems.
 2- Describe the process of digestion
in animals.
 3- Describe the absorption of
nutrients in animals.

Digestive Systems



Digestion is a process
that breaks feed down
into simple
substances that can
be absorbed by the
body.
This usually involves
mechanical, chemical
and enzymes.
The compounds are
then absorbed into
the blood stream.
Digestive tract
Also known as the gastrointestinal
tract or the alimentary tract.
 Begins at the mouth and ends at the
anus.

Three kinds of digestive
systems.
Non-ruminant (monogastric).
 Ruminant (polygastric).
 Avian

Non-ruminant digestive
systems.
Swine, horses & humans.
 Single compartment stomach.
 Includes, mouth, teeth, tongue,
salivary glands, esophagus,
stomach, small intestine, liver,
pancreas, cecum, large intestine,
rectum and anus.

Parts of Swine Digestive
Tract


Parts of the
swine
digestive
system.
Know
location and
function of
each part.
Parts of Horse Digestive
System


Know the location
and function of
each part.
Pay particular
attention to the
highly adapted
cecum.
Mouth, part of digestive
system.




The mouth contains the teeth, tongue,
and salivary glands.
Chewing action (mechanical part of
digestion).
Food is cut and torn in the mouth, then
mixed with saliva, which is produced in
three different places.
Three paired sets of salivary glands,
located under the lower jaw and under
the ears.
Mouth
Saliva contains water, mucin,
bicarbonate salts and enzymes.
 Horse saliva does not contain
enzymes.
 In swine, saliva contains the
enzymes salivary amylase and
salivary maltase.

Enzymes




Enzymes work in the whole digestive
process, form mouth to anus.
Enzymes are organic catalysts that cause
and/or speed up digestive action.
However, enzymes remain unchanged in
this process.
A weak acid solution will halt enzyme
action.
Digestion in the Mouth
Saliva stimulates the taste nerves.
 Water moistens the feed for chewing
and swallowing.
 Mucin lubricates the feed for
swallowing.
 Bicarbonate salts buffer the pH in
the stomach.

The Tongue
The tongue gathers feed in the
mouth.
 Directs the feed in the throat for
swallowing.
 Mixes feed.

Esophagus
A tube like passage which leads
from the mouth to the stomach.
 Peristaltic waves send feed down the
esophagus, (muscle contractions).
 The cardia, located at the end of the
esophagus prevents feed in the
stomach from coming back into the
esophagus. ( non-ruminants)

Stomach



Pear shaped, muscular organ, receives
feed, where it is further broken down by
muscle in the stomach wall.
Gastric juices, secreted by the glands in
the stomach wall, start to flow the
moment masticated feed enter the
stomach.
Gastric juices have about 0.2 to 0.5
percent HCl.
Stomach



The wall of the stomach is lined with
muscle, this muscle churns and squeezes
the feed.
This action forces the liquid portion on
into the small intestine.
The stomach of the horse has less
muscular activity than that of other
species, causing an increased tendency
toward digestive disorders.
Horse Stomach
The stomach of a horse is smaller,
compared to other species, in
relation to the size of the animal.
 Therefore, it is more desirable to
feed horses in smaller amounts at
one time but provide more frequent
feedings.

Small Intestine





Duodenum, the first part of the small
intestine.
This is where secretions from the
pancreas, liver and intestinal walls occur.
Active digestion takes place here.
Bile, secreted in the liver is stored in the
gallbladder where it is secreted into the
duodenum.
Horses do not have a gallbladder,
therefore, bile is secreted continuously
from the liver to the duodenum.
Small Intestine
The middle part of the Small
Intestine is called the Jejunum.
 The last part of the small intestine is
called the ileum.
 Nutrient absorption occurs in these
two section of the small intestine.

Small Intestine




Chyme is partially digested feed in the
stomach.
Chyme is an acid, semi fluid, gray, pulpy
mass.
Pancreatic juice is secreted by the
pancreas, a small gland located between
the folds of the small intestine.
Pancreatic juice contains enzymes.
Small Intestine, Proteins




Proteins are further broken down into
polypeptides oligopeptides, dipeptides
and amino acids, eventually broken down
into simple amino acids.
Starch is changed to maltose.
Fats in the feed are broken down into
fatty acids glycerol and monoglycerides.
Bile helps emulsify fats.
Large Intestine in Swine
The small intestine does the
majority of absorption.
 Cecum in swine has little or no
function.
 The cecum is the first part of the
large intestine.
 The colon is the middle and largest
part of the large intestine.

Large Intestine, Horses





Cecum is an important organ in horses.
The large intestine makes up
approximately 60% of the total digestive
tract.
Divided into cecum, large colon, small
colon and rectum.
Horses can use large amounts of
roughage because of the presence of
bacteria in the cecum and colon.
These bacteria digest hemicelluloses and
cellulose and ferment carbohydrates.
Large Intestine, Horses
IMPORTANT- because the large
intestine of the horse usually
contains substantial quantities of
ingested material, impaction occurs
easily.
 This impaction is the start of what
horse ailment?

Large Intestine





In all species, undigested, unabsorbed
and indigestible material passes from the
small intestine to the large.
The main function of the L intestine is to
absorb water from the material passing
through.
In the Horse, the small colon is the site of
most of the water resorption.
Feces, material that is not absorbed or
digested.
Anus, the external opening at the end of
the digestive tract.
Ruminant Digestive System
Mouth





Saliva of ruminants does not contain
enzymes to help digest the starches.
It contains buffers which neutralize the
fatty acid produced in the rumen.
The rumen contents are maintained at
approximately a pH of 6-6.5.
This pH level promotes microbial growth
in the rumen.
Mature cows produce about 12 gallons of
saliva per day while sheep produce 2 gal.
Ruminant Digestion
Stomach.






The stomach of the ruminant contains
four compartments: the rumen,
reticulum, omasum and the abomasum.
The rumen or paunch is the first.
The reticulum or honey comb is second.
There is not a clear partition between
these two compartments.
The cardia, (lower part of the esophagus
is common to both compartments.
No enzymes are secreted in these tow
parts.
Ruminant Digestion
Stomach





The third compartment is the omasum or
many plies.
It constitutes 8% of the stomach.
The omasum contains strong muscles in
the walls.
The fourth and last part of the ruminant
stomach is the abomasum or true
stomach.
The Abomasum makes up 7% of the
stomach.
Ruminant Digestion
Ruminants eat rapidly swallowing
much of their feed without chewing.
 Solid feed goes to the rumen.
 The liquid part also goes into the
rumen. But passes quickly to the
reticulum, then through the omasum
and on into the abomasum.

Esophageal Groove



These two muscular folds for a passage
way from the cardia, ( the end of the
esophagus), to the omasum.
When closed this passage way directs
feed from the esophagus directly to the
omasum and when it is open the material
goes into the rumen and the reticulum.
Its major function appears to be to allow
milk ingest by a nursing animal to bypass
fermentation in the rumen. Serves no
purpose in adult ruminants.
Bovine Digestive system

Identify
location and
function of
each of the
parts of the
Bovine
digestive
system.
Rumination




After the ruminant animal has filled the
rumen with feed it lies down to ruminate,
(chew its cud).
Cattle spend from 5-7 hours ruminating,
broken up into 6-8 rumination periods.
Regurgitation is the process of forcing the
feed back into the mouth for chewing.
This is done through series of muscular
contractions and pressure in the rumen
and reticulum.
Rumination




The animal breathes in with a closed
glottis.
This causes a drop in pressure in the
thorax and esophagus.
The pressure in the rumen is now greater,
forcing the cud into the esophagus where
it is carried to the mouth, with muscular
contractions.
More saliva is then mixed with the feed
and it passes into the reticulum, if
sufficient chewing has been done.
Rumen Microorganisms



Rumen and reticulum contain millions of
microorganisms called bacteria and
protozoa.
Together, these tiny organisms feed on
the fibrous material in the rumen.
They digest cellulose and compiles starch,
synthesize protein and synthesize
vitamins.
Microorganisms




The three types of rumen bacteria are
streptococci, lactobacilli and celluloytic
bacteria.
50-65% of the starch is digested in the
rumen.
Protein in the rumen is converted to
ammonia, organic acids and amino acids.
Most amino acids synthesized by the
rumen, therefore, it is not necessary to
supply large quantities of amino acids in
the ration.
Functions of the Rumen




There is continual flow of feed materials
into and out of the rumen.
It acts like a large fermentation vat and
account for about 50-85% of the total
utilization of the digestible dry matter in
the ration.
Saliva which is mixed with feed helps
control the pH of the rumen.
A shift of microorganisms can result from
the types of feed fed.
Function of the Rumen



Feed material stays in the rumen and
reticulum area from about two hours to
several days.
The kind of feed influences time.
Concentrates pass quicker than
roughages.
Papillae line the interior wall of the
rumen, they increase surface area
therefore increasing the absorption ability
of the rumen wall.
Function of the Rumen




Bacterial action in the rumen produces
large quantities (30-50 quarts per hour)
of gas, mainly CO2 and CH4.
This gas must be removed or the animal
will bloat.
The gas is released through eructation,
(belching).
Small amounts are absorbed by the
bloodstream and then eliminated through
the lungs.
Function of the Reticulum




Contains the same bacteria and protozoa
as the rumen.
Lined with intersecting ridges that form
honeycomblike projections.
Hardware that is ingest are trapped in
this area and generally do not move
further through the digestive system.
Feed is moved back and forth between
the rumen and reticulum by regular
contractions originating in the reticulum.
Function of the Omasum
The omasum grinds and squeezes
the feed.
 Little or no digestive action.
 The material leaving the omasum is
60-70 percent drier than the
material entering it.

Function of the Abomasum





Digestion here is much the same as it is
in a monogastric animal.
Digestive juices are added to the feed
and it is moistened.
There is little or no digestion of fat,
cellulose or starch.
pH level of 3.5-4.0.
The feed becomes highly fluid as it passes
into the small intestine.
Avian Digestive Systems



Different from nonruminant and
ruminant.
Feed in proventriculus are secreted by the
glandular stomach and mixed with feed.
The feed next moves to the gizzard.
Epithelium breaks the feed into smaller
particles, further mixing of proventricular
digestive juices with the feed in the
gizzard.The end of the digestive system is
the vent.
Absorption of Nutrients



Absorption is the process of taking
nutrients from the digested feed into the
blood and lymph systems.
In nonruminants most absorption takes
place from the small intestine with a
lesser amount being absorbed from the
large intestine.
In ruminants there is some absorption of
nutrients through the wall of the rumen.
Absorption of Nutrients





Villi are small cone-shaped projection on
the wall of the small intestine. Each villi
contains a network of blood capillaries
through which nutrients enter the blood
stream.
Protein is converted to amino acids.
Starches and sugars are converted to
glucose, fructose and galactose.
Crude fiber is converted to short chained
fatty acids or glucose by digestion.
These nutrients pass into the blood
capillaries by osmosis through the semi
permeable membranes.
Absorption of Nutrients




The two methods of absorption are
diffusion and active transport.
Diffusion is the movement of molecules
from an area of high concentration to one
of low concentration.
Active transport is the movement of
molecules from one area to another
requiring the expenditure of energy.
Amino acids and glucose move by active
transport.
Metabolism



Metabolism is the sum of the chemical
and physical changes continually
occurring in living organisms and cells
utilizing nutrients.
Anabolism is the formation and repair of
body tissues.
Catabolism is the breakdown of body
tissue into simpler substances.
Nutrient Transport



Nutrients in the water soluble form, are
primarily carried by the blood in the
animals body from where they are
absorbed to where they are utilized.
Nutrients are used for maintenance,
oxidation provides hear for body
temperature and movement.
Nutrients are also used fro growth and
fattening, fetal development, production
of milk and eggs, wool and mohair and
work.
Summary



Digestion is breaking feed down into
simple substances that can be absorbed
by the body.
Digestion occurs when feeds are broken
up mechanically and acted upon by
enzymes and other digestive juices.
Most absorption of nutrients after
digestion takes place in the small
intestine, although some absorption
occurs in the rumen.
Review Questions
1- Define digestion and digestive
system.
 2- Name the three major kinds of
digestive systems and give
examples of animals with each type.
 3- Name the parts of the
monogastric digestive system and
briefly describe the function of each.

Review Questions





4- Devine and give examples of
enzymes.
6- Define chyme.
7- Describe the function of the liver.
9- Name the four major compartments of
the stomach of a ruminant.
10- Describe the function of each
compartment.
Review Questions
13- Name the major
microorganisms found in the rumen
and describe their function.
 15- Describe how absorption of
nutrients occurs.
 16- Define and briefly describe
metabolism.

Review Answers

1- Digestion: mechanical, chemical,
and enzymic actions that break feed
down into simple substances that
can be absorbed by the body.
Digestive system: the passage
through the body that begins at the
mouth and ends with the anus
through which feed passes as it is
digested.
Review Answers




2- Non ruminant: Swine and horses.
Ruminant: Cattle, sheep and goats.
Avian: Poultry.
3- Mouth: Teeth tongue and salivary
glands. Chewing action mechanical
digestion. Esophagus, passageway to the
stomach. Small Intestine, the duodenum,
jejunum and ileum, the site of most of
the absorption. Gallbladder and liver
production of bile, storage of wastes.
Villi, moves food through the stomach,
aids in absorption. Cecum, non-functional
in swine, aids in roughage digestion in
horses. Colon, with the help of bacteria
breaks down roughages. Rectum????
Review Answers




4- Organic catalysts that cause and/or
speed up digestive action but remain
unchanged in the process. Examples:
amylase, maltase, lipase,
carboxypeptidase, peptidase, sucrase,
lactase, nucleotidase and cellulase.
6- Partially digested feed in the stomach.
7- Secretes bile.
9- Rumen, Reticulum, omasum and
abomasum.
Review Answers

10- Rumen and Reticulum: Fat to form
fatty acids and glycerol; glycerol to form
propionic acid; site of microorganisms
that act on protein/nonprotein nitrogen to
form essential amino acids;
starch/sucrose/cellulose. Omasum:
Grinds and squeezes feed, removes some
liquid; little digestive action in the
omasum. Abomasum: true stomach, acts
on proteins; stops action of salivary
amylase; contains HCl.
Review Answers



13- Streptococci & Lactobacilli -Digests
starches and sugars; rations of high
concentrates and young tender forages
will increase Streptococci and Lactobacilli.
Bacteriodes succinogenes and
Ruminococcus flavefaciens Digest
cellulose and hemicellulose.
Protozoa digest polysaccharides, ferment
cellulose.
Review Answers

15- Most absorption is done by
diffusion and active transport. Most
in the non-ruminant stomach is
done in the small intestine, in
ruminant animals they use the small
intestine and to a small degree
through the rumen.
Review Answers

16- Metabolism refers to the
chemical and physical changes
occurring after the feed nutrients
are absorbed into the bloodstream.
Livestock Nutrition
Ch. 2
Digestion in Animals
Objectives
1- Describe the nonruminant
(monogastric), ruminant, and avian
digestive systems.
 2- Describe the process of digestion
in animals.
 3- Describe the absorption of
nutrients in animals.

Digestive Systems



Digestion is a process
that breaks feed down
into simple
substances that can
be absorbed by the
body.
This usually involves
mechanical, chemical
and enzymes.
The compounds are
then absorbed into
the blood stream.
Digestive tract
Also known as the gastrointestinal
tract or the alimentary tract.
 Begins at the mouth and ends at the
anus.

Three kinds of digestive
systems.
Non-ruminant (monogastric).
 Ruminant (polygastric).
 Avian

Non-ruminant digestive
systems.
Swine, horses & humans.
 Single compartment stomach.
 Includes, mouth, teeth, tongue,
salivary glands, esophagus,
stomach, small intestine, liver,
pancreas, cecum, large intestine,
rectum and anus.

Parts of Swine Digestive
Tract


Parts of the
swine
digestive
system.
Know
location and
function of
each part.
Parts of Horse Digestive
System


Know the location
and function of
each part.
Pay particular
attention to the
highly adapted
cecum.
Mouth, part of digestive
system.




The mouth contains the teeth, tongue,
and salivary glands.
Chewing action (mechanical part of
digestion).
Food is cut and torn in the mouth, then
mixed with saliva, which is produced in
three different places.
Three paired sets of salivary glands,
located under the lower jaw and under
the ears.
Mouth
Saliva contains water, mucin,
bicarbonate salts and enzymes.
 Horse saliva does not contain
enzymes.
 In swine, saliva contains the
enzymes salivary amylase and
salivary maltase.

Enzymes




Enzymes work in the whole digestive
process, form mouth to anus.
Enzymes are organic catalysts that cause
and/or speed up digestive action.
However, enzymes remain unchanged in
this process.
A weak acid solution will halt enzyme
action.
Digestion in the Mouth
Saliva stimulates the taste nerves.
 Water moistens the feed for chewing
and swallowing.
 Mucin lubricates the feed for
swallowing.
 Bicarbonate salts buffer the pH in
the stomach.

The Tongue
The tongue gathers feed in the
mouth.
 Directs the feed in the throat for
swallowing.
 Mixes feed.

Esophagus
A tube like passage which leads
from the mouth to the stomach.
 Peristaltic waves send feed down the
esophagus, (muscle contractions).
 The cardia, located at the end of the
esophagus prevents feed in the
stomach from coming back into the
esophagus. ( non-ruminants)

Stomach



Pear shaped, muscular organ, receives
feed, where it is further broken down by
muscle in the stomach wall.
Gastric juices, secreted by the glands in
the stomach wall, start to flow the
moment masticated feed enter the
stomach.
Gastric juices have about 0.2 to 0.5
percent HCl.
Stomach



The wall of the stomach is lined with
muscle, this muscle churns and squeezes
the feed.
This action forces the liquid portion on
into the small intestine.
The stomach of the horse has less
muscular activity than that of other
species, causing an increased tendency
toward digestive disorders.
Horse Stomach
The stomach of a horse is smaller,
compared to other species, in
relation to the size of the animal.
 Therefore, it is more desirable to
feed horses in smaller amounts at
one time but provide more frequent
feedings.

Small Intestine





Duodenum, the first part of the small
intestine.
This is where secretions from the
pancreas, liver and intestinal walls occur.
Active digestion takes place here.
Bile, secreted in the liver is stored in the
gallbladder where it is secreted into the
duodenum.
Horses do not have a gallbladder,
therefore, bile is secreted continuously
from the liver to the duodenum.
Small Intestine
The middle part of the Small
Intestine is called the Jejunum.
 The last part of the small intestine is
called the ileum.
 Nutrient absorption occurs in these
two section of the small intestine.

Small Intestine




Chyme is partially digested feed in the
stomach.
Chyme is an acid, semi fluid, gray, pulpy
mass.
Pancreatic juice is secreted by the
pancreas, a small gland located between
the folds of the small intestine.
Pancreatic juice contains enzymes.
Small Intestine, Proteins




Proteins are further broken down into
polypeptides oligopeptides, dipeptides
and amino acids, eventually broken down
into simple amino acids.
Starch is changed to maltose.
Fats in the feed are broken down into
fatty acids glycerol and monoglycerides.
Bile helps emulsify fats.
Large Intestine in Swine
The small intestine does the
majority of absorption.
 Cecum in swine has little or no
function.
 The cecum is the first part of the
large intestine.
 The colon is the middle and largest
part of the large intestine.

Large Intestine, Horses





Cecum is an important organ in horses.
The large intestine makes up
approximately 60% of the total digestive
tract.
Divided into cecum, large colon, small
colon and rectum.
Horses can use large amounts of
roughage because of the presence of
bacteria in the cecum and colon.
These bacteria digest hemicelluloses and
cellulose and ferment carbohydrates.
Large Intestine, Horses
IMPORTANT- because the large
intestine of the horse usually
contains substantial quantities of
ingested material, impaction occurs
easily.
 This impaction is the start of what
horse ailment?

Large Intestine





In all species, undigested, unabsorbed
and indigestible material passes from the
small intestine to the large.
The main function of the L intestine is to
absorb water from the material passing
through.
In the Horse, the small colon is the site of
most of the water resorption.
Feces, material that is not absorbed or
digested.
Anus, the external opening at the end of
the digestive tract.
Ruminant Digestive System
Mouth





Saliva of ruminants does not contain
enzymes to help digest the starches.
It contains buffers which neutralize the
fatty acid produced in the rumen.
The rumen contents are maintained at
approximately a pH of 6-6.5.
This pH level promotes microbial growth
in the rumen.
Mature cows produce about 12 gallons of
saliva per day while sheep produce 2 gal.
Ruminant Digestion
Stomach.






The stomach of the ruminant contains
four compartments: the rumen,
reticulum, omasum and the abomasum.
The rumen or paunch is the first.
The reticulum or honey comb is second.
There is not a clear partition between
these two compartments.
The cardia, (lower part of the esophagus
is common to both compartments.
No enzymes are secreted in these tow
parts.
Ruminant Digestion
Stomach





The third compartment is the omasum or
many plies.
It constitutes 8% of the stomach.
The omasum contains strong muscles in
the walls.
The fourth and last part of the ruminant
stomach is the abomasum or true
stomach.
The Abomasum makes up 7% of the
stomach.
Ruminant Digestion
Ruminants eat rapidly swallowing
much of their feed without chewing.
 Solid feed goes to the rumen.
 The liquid part also goes into the
rumen. But passes quickly to the
reticulum, then through the omasum
and on into the abomasum.

Esophageal Groove
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These two muscular folds for a passage
way from the cardia, ( the end of the
esophagus), to the omasum.
When closed this passage way directs
feed from the esophagus directly to the
omasum and when it is open the material
goes into the rumen and the reticulum.
Its major function appears to be to allow
milk ingest by a nursing animal to bypass
fermentation in the rumen. Serves no
purpose in adult ruminants.
Bovine Digestive system

Identify
location and
function of
each of the
parts of the
Bovine
digestive
system.
Rumination
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After the ruminant animal has filled the
rumen with feed it lies down to ruminate,
(chew its cud).
Cattle spend from 5-7 hours ruminating,
broken up into 6-8 rumination periods.
Regurgitation is the process of forcing the
feed back into the mouth for chewing.
This is done through series of muscular
contractions and pressure in the rumen
and reticulum.
Rumination

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The animal breathes in with a closed
glottis.
This causes a drop in pressure in the
thorax and esophagus.
The pressure in the rumen is now greater,
forcing the cud into the esophagus where
it is carried to the mouth, with muscular
contractions.
More saliva is then mixed with the feed
and it passes into the reticulum, if
sufficient chewing has been done.
Rumen Microorganisms



Rumen and reticulum contain millions of
microorganisms called bacteria and
protozoa.
Together, these tiny organisms feed on
the fibrous material in the rumen.
They digest cellulose and compiles starch,
synthesize protein and synthesize
vitamins.
Microorganisms



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The three types of rumen bacteria are
streptococci, lactobacilli and celluloytic
bacteria.
50-65% of the starch is digested in the
rumen.
Protein in the rumen is converted to
ammonia, organic acids and amino acids.
Most amino acids synthesized by the
rumen, therefore, it is not necessary to
supply large quantities of amino acids in
the ration.
Functions of the Rumen



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There is continual flow of feed materials
into and out of the rumen.
It acts like a large fermentation vat and
account for about 50-85% of the total
utilization of the digestible dry matter in
the ration.
Saliva which is mixed with feed helps
control the pH of the rumen.
A shift of microorganisms can result from
the types of feed fed.
Function of the Rumen



Feed material stays in the rumen and
reticulum area from about two hours to
several days.
The kind of feed influences time.
Concentrates pass quicker than
roughages.
Papillae line the interior wall of the
rumen, they increase surface area
therefore increasing the absorption ability
of the rumen wall.
Function of the Rumen



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Bacterial action in the rumen produces
large quantities (30-50 quarts per hour)
of gas, mainly CO2 and CH4.
This gas must be removed or the animal
will bloat.
The gas is released through eructation,
(belching).
Small amounts are absorbed by the
bloodstream and then eliminated through
the lungs.
Function of the Reticulum




Contains the same bacteria and protozoa
as the rumen.
Lined with intersecting ridges that form
honeycomblike projections.
Hardware that is ingest are trapped in
this area and generally do not move
further through the digestive system.
Feed is moved back and forth between
the rumen and reticulum by regular
contractions originating in the reticulum.
Function of the Omasum
The omasum grinds and squeezes
the feed.
 Little or no digestive action.
 The material leaving the omasum is
60-70 percent drier than the
material entering it.

Function of the Abomasum





Digestion here is much the same as it is
in a monogastric animal.
Digestive juices are added to the feed
and it is moistened.
There is little or no digestion of fat,
cellulose or starch.
pH level of 3.5-4.0.
The feed becomes highly fluid as it passes
into the small intestine.
Avian Digestive Systems



Different from nonruminant and
ruminant.
Feed in proventriculus are secreted by the
glandular stomach and mixed with feed.
The feed next moves to the gizzard.
Epithelium breaks the feed into smaller
particles, further mixing of proventricular
digestive juices with the feed in the
gizzard.The end of the digestive system is
the vent.
Absorption of Nutrients



Absorption is the process of taking
nutrients from the digested feed into the
blood and lymph systems.
In nonruminants most absorption takes
place from the small intestine with a
lesser amount being absorbed from the
large intestine.
In ruminants there is some absorption of
nutrients through the wall of the rumen.
Absorption of Nutrients





Villi are small cone-shaped projection on
the wall of the small intestine. Each villi
contains a network of blood capillaries
through which nutrients enter the blood
stream.
Protein is converted to amino acids.
Starches and sugars are converted to
glucose, fructose and galactose.
Crude fiber is converted to short chained
fatty acids or glucose by digestion.
These nutrients pass into the blood
capillaries by osmosis through the semi
permeable membranes.
Absorption of Nutrients




The two methods of absorption are
diffusion and active transport.
Diffusion is the movement of molecules
from an area of high concentration to one
of low concentration.
Active transport is the movement of
molecules from one area to another
requiring the expenditure of energy.
Amino acids and glucose move by active
transport.
Metabolism



Metabolism is the sum of the chemical
and physical changes continually
occurring in living organisms and cells
utilizing nutrients.
Anabolism is the formation and repair of
body tissues.
Catabolism is the breakdown of body
tissue into simpler substances.
Nutrient Transport



Nutrients in the water soluble form, are
primarily carried by the blood in the
animals body from where they are
absorbed to where they are utilized.
Nutrients are used for maintenance,
oxidation provides hear for body
temperature and movement.
Nutrients are also used fro growth and
fattening, fetal development, production
of milk and eggs, wool and mohair and
work.
Summary



Digestion is breaking feed down into
simple substances that can be absorbed
by the body.
Digestion occurs when feeds are broken
up mechanically and acted upon by
enzymes and other digestive juices.
Most absorption of nutrients after
digestion takes place in the small
intestine, although some absorption
occurs in the rumen.
Review Questions
1- Define digestion and digestive
system.
 2- Name the three major kinds of
digestive systems and give
examples of animals with each type.
 3- Name the parts of the
monogastric digestive system and
briefly describe the function of each.

Review Questions





4- Devine and give examples of
enzymes.
6- Define chyme.
7- Describe the function of the liver.
9- Name the four major compartments of
the stomach of a ruminant.
10- Describe the function of each
compartment.
Review Questions
13- Name the major
microorganisms found in the rumen
and describe their function.
 15- Describe how absorption of
nutrients occurs.
 16- Define and briefly describe
metabolism.

Review Answers

1- Digestion: mechanical, chemical,
and enzymic actions that break feed
down into simple substances that
can be absorbed by the body.
Digestive system: the passage
through the body that begins at the
mouth and ends with the anus
through which feed passes as it is
digested.
Review Answers


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2- Non ruminant: Swine and horses.
Ruminant: Cattle, sheep and goats.
Avian: Poultry.
3- Mouth: Teeth tongue and salivary
glands. Chewing action mechanical
digestion. Esophagus, passageway to the
stomach. Small Intestine, the duodenum,
jejunum and ileum, the site of most of
the absorption. Gallbladder and liver
production of bile, storage of wastes.
Villi, moves food through the stomach,
aids in absorption. Cecum, non-functional
in swine, aids in roughage digestion in
horses. Colon, with the help of bacteria
breaks down roughages. Rectum????
Review Answers
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4- Organic catalysts that cause and/or
speed up digestive action but remain
unchanged in the process. Examples:
amylase, maltase, lipase,
carboxypeptidase, peptidase, sucrase,
lactase, nucleotidase and cellulase.
6- Partially digested feed in the stomach.
7- Secretes bile.
9- Rumen, Reticulum, omasum and
abomasum.
Review Answers

10- Rumen and Reticulum: Fat to form
fatty acids and glycerol; glycerol to form
propionic acid; site of microorganisms
that act on protein/nonprotein nitrogen to
form essential amino acids;
starch/sucrose/cellulose. Omasum:
Grinds and squeezes feed, removes some
liquid; little digestive action in the
omasum. Abomasum: true stomach, acts
on proteins; stops action of salivary
amylase; contains HCl.
Review Answers



13- Streptococci & Lactobacilli -Digests
starches and sugars; rations of high
concentrates and young tender forages
will increase Streptococci and Lactobacilli.
Bacteriodes succinogenes and
Ruminococcus flavefaciens Digest
cellulose and hemicellulose.
Protozoa digest polysaccharides, ferment
cellulose.
Review Answers

15- Most absorption is done by
diffusion and active transport. Most
in the non-ruminant stomach is
done in the small intestine, in
ruminant animals they use the small
intestine and to a small degree
through the rumen.
Review Answers

16- Metabolism refers to the
chemical and physical changes
occurring after the feed nutrients
are absorbed into the bloodstream.