Brandon Gadberry
Animal Science Bio
Test 2
Material: Unit 8, Unit 9, Lab Notes 5A & 5B and online animal bone homework
Unit 8
Animal Nutrition: Digestion
 Digestion- breakdown of complex molecules present in feedstuffs into their
smaller, individual components.
o Digest starchindividual molecules of glucose
 Absorption- transport of these small molecules across the wall of the digestive
tract into the bloodstream
 Carnivores- primarily meat (proteins, fats, bone)
o Easy diet for animals to digest
o Short and simple digestive tract
o Dogs and cats
 Omnivores- significant amounts of both plants and animals in their diet.
o Plant- seeds and fruits, rich in starch, sugars, and oils.
o Easily digested; relatively simple digestive tracts
o Pigs and humans
 Herbivores- nutrients from plant food products
o Low-fiber herbivores; consume primarily seeds and fruits
 Can digest starches, sugars, and oils quite readily
o High-fiber herbivores; consume primarily leaves and stems
 Consume plants rich in cellulose and other fiber
 Animals lack enzymes needed to break down the beta-1,4
glycosidic bond that links glucose molecules together in cellulose.
 Depend on microorganisms
 Animals that have this have digestive tracts with large capacities
 Most of our commercially important livestock species are high
fiber herbivores.
Digestive Process- breakdown of complex feedstuffs into absorbable nutrients
 Mechanical Process
o Mastication- chewing
 Reduces the particle size of feedstuffs, making it easier for them to
move down the digestive tract and increasing the surface area that
is exposed to other digestive processes.
o Mixing- keeps food material exposed to the other digestive process
 Parts of the rumen are constantly undergoing contractions to aid
mixing
o Peristalsis- rhythmic, coordinated contraction of the gut that is the primary
means of moving food from one part of the digestive tract to the next.


Chemical Process
o Enzymatic and nonenzymatic
 Enzymes are protein molecules that catalyze biochemical reactions
 Digestive enzymes are enzymes that catalyze the breakdown of
feedstuffs in the digestive tract.
 Pancreatic amylase secreted from pancreas and breaks
starch down into the disaccharide maltose
 Non-enzymatic; stomach secretes hydrochloric acid to assist
protein digestion
Mechanical Process
o How cellulose and other fibrous materials are broken down
Anatomy of the Digestive Tract: MONOGASTRIC ANIMALS
 Monogastric animals; simple stomached animals
PIG
Types of digestion
Starch
Protein
Fat
Cellulose
Mouth; Saliva
(contains buffers
that neutralize
acids)
Mechanical
(mastication)
NONE
NONE
NONE
Esophagus
NONE
NONE
NONE
Stomach
Mechanical
(peristalsis)
Chemical (protein)
Ptyalin begins
breaking down
alpha-1,4
glycosidic
bonds
NONE
NONE
NONE
Small Intestine;
duodenum,
jejunum, ileum
-Bile
(synthesized
in the liver
and stored
in the gall
bladder)
-Pancreatic
lipase
breaks the
bond
between
glycerol and
fatty acids
NONE
Chemical (starch,
fat, protein)
NONE
-Microbial digestion
Large Intestine;
Cecum and colon
Microbial
NONE
-Pepsin and HCl
cleave specific
peptide bonds
-Pancreatic
-Pancreatic
amylase breaks enzymes(trypsin,
starch into
chymotrypsin,
maltose
and
-Intestinal
carbopeptidase)
maltase breaks cleave specific
down maltose
peptide bonds
into glucose
which can be
Aminopeptidases
absorbed
and dipeptidases
-Glucose is
break down
transported into peptides into
the intestinal
individual amino
cells by
acids
specific
-Individual
glucose
amino acids are
transport
absorbed by
proteins
specific amino
acid transport
proteins
NONE
NONE
break down beta-1,4
glycosidic bonds


How does digestion differ for horses?
o Mouth: Same as pig
o Stomach: same as pig
o Small Intestine: same as pig
o Large Intestine:
 Increased size and complexity
 Slow transit time
 Better utilization of Volatile Fatty Acids released by microbes
How does digestion differ for chickens?
o Mouth:
 No saliva
 No mastication
o Esophagus
 Food storage in crop
o Stomach (2 parts)
 Proventriculus (Chemical Digestion)
 Gizzard (reduce particle size)
o Small Intestine: Same as pig and horse
o Large Intestine
 2 ceca, otherwise similar to pigs
Ruminant

Primary types of digestion
o Mouth
o Esophagus
o Stomach
 Rumen
 Reticulum
 Omasum
 Abomasum
o Small Intestine
o Large Intestine
Cellulose
Protein
Mouth
Types of
Starch
digestion
Mechanical NONE
NONE
NONE
Esophagus
Mechanical NONE
NONE
NONE
Rumen
Microbial
Microbes break
beta-1,4
glycosidic
bonds
- Use glucose
for own
metabolism and
release Volatile
- Microbes use
the protein for
themselves and
convert it to
microbial protein
Ruminant
Microbes break beta-1,4
glycosidic bonds
- Use glucose for own
metabolism and release Volatile
Fatty Acids
-Volatile Fatty acids are absorbed
by the animal
Reticulum
Microbial
NONE
Fatty Acids
-Volatile Fatty
acids are
absorbed by the
animal
NONE
Omasum
Microbial
NONE
NONE
NONE
Abomasum
Chemical
NONE
NONE
Small
Intestine
Chemical
NONE
NONE
-Lysozyme
breaks down
bacterial cell
walls
-HCl and pepsin
cleave peptide
bonds
-pancreatic
enzymes(trypsin,
chymotrypsin,
and
carboxypeptidase)
cleave specific
peptide bonds
-Amino
peptidases and
dipeptidases
break peptides
into individual
amino acids
-Individual amino
acids are
absorbed by
specific amino
acid transport
proteins
Large Intestine
Microbial
NONE
-Microbes break
down beta-1,4
glycosidic bonds
and use the
resulting free
glucose for their
own metabolism
NONE
NONE
Unit 8 Questions
1. What are the three major groups that animals can be classified in based on their
principal source of nutrients?
o Omnivore, herbivore, and carnivore.
2. Distinguish between low-fiber and high fiber herbivores.
o Low fiber herbivores: consume primarily seeds and fruit. Can digest
starches, sugars, and oils.
o High fiber herbivores: consume primarily leaves and stems. Consume
parts of the plant that are rich in cellulose and other fiber.
3. What are the three major digestive processes and give examples of each?
o Mechanical: Mastication in the mouth, Mixing, and Peristalsis
o Chemical: Enzymatic and Non-enzymatic; stomach secretes
hydrochloric acid to assist protein digestion.
o Microbial: cellulose is broke down
4. Identify each of the major parts of the digestive tract from a Monogastric animal.
o Mouth: mechanical digestion (mastication)
o Esophagus: Mechanical digestion (peristalsis)
o Stomach: chemical digestion (protein)
o Small Intestine: chemical digestion (starch, fat, and protein)
o Large Intestine: microbial digestion
5. Identify the products secreted by each of these parts and how they contribute to
digestion.
o Mouth: Saliva- helps soften the food and serves as a lubricant for its
passage further in the digestive tract. Contains buffers that neutralize
acids. Also contains ptyalin that breaks down alpha-1,4 glycosidic
bonds.
o Esophagus: Nothing
o Stomach:
 Hydrochloric acid- breakdown the peptide bonds
 Pepsin-proteolytic enzyme; cleaves peptide bonds between
specific pairs of amino acids
o Small Intestine:
 Bile- bile is synthesized in the liver and stored in the gall
bladder; released in the duodenum; it breaks up fat into
smaller particles to mix more efficiently. This is an important
for of nonenzymatic, chemical digestion.
 Pancreatic lipase- breaks the ester bonds that link fatty acids
to glycerol in triglycerides and phospholipids.
 Pancreatic amylase- breaks down starch into maltose
o Large Intestine
 Cellulolytic enzymes- cleave the beta-1,4 glycosidic bonds that
link glucose to molecules in cellulose.
6. What is a proteolytic enzyme? Give some examples.
o A group of enzymes that break the long chainlike molecules of
proteins into shorter fragments (peptides) and eventually into their,
components amino acids. An example is pepsin.
7. Describe how starch, cellulose, triglycerides, and proteins are digested in each
part of the digestive tract.
o SEE CHART ABOVE FOR MONOGASTRIC
8. Describe where and how nutrients are absorbed into the bloodstream.
o Nutrients are absorbed in the bloodstream in the large intestine and
since volatile fatty acids are very soluble the can easily cross the large
intestine wall and into the bloodstream.
9. Be able to describe where digestion begins, continues, and is completed for
starch, cellulose, triglycerides, and protein.
o Starch: begins in mouth and ends in small intestine
o Cellulose: begins and ends in large intestine
o Triglycerides: begins and ends in small intestine
o Protein: begins and ends in small intestine
10. In addition to digestion, describe the functions of the large intestine.
o The large intestine can be use to provide Volatile Fatty Acids as a
source of energy as well as the microbes synthesizing vitamins. The
large intestine is also a major site for water reabsorption.
11. Describe how the digestive system of the horse has been adapted to a high-fiber
diet.
o It has adapted to a high-fiber diet in a simple manner. First, its teeth
are designed to harvest and chew fibrous feedstuffs. The incisors are
designed to shear grass stems and check teeth are hypsodont with
parallel ridges of enamel that are very effective for chewing/grinding
surface. Second, horses have retained the basic elements of the
Monogastric tract except they have greatly increased the capacity for
fiber digestion by expanding the cecum and colon.
12. Describe how each of these parts in the digestive tract of poultry differs from the
corresponding part in Monogastric mammals: mouth, esophagus, stomach, cecum.
o Mouth: No saliva and no mastication
o Esophagus: Food storage in the crop
o Stomach: Proventriculus (chemical digestion) and Gizzard (reduce
particle size)
o Cecum: 2 ceca instead of one
13. Name the four compartments of the ruminant stomach.
o Rumen, Reticulum, Omasum, Abomasum
14. Describe how each compartment functions in digestion
o Rumen: microbial digestion- ruminate or regurgitate food to
maximize efficiency of microbial digestion
o Reticulum: microbial digestion- Filter; inside of the reticulum is
honeycomb shaped ridges and catch larger particles of leaves and
stems and push them back into the rumen
o Omasum: microbial- secondary filter; numerous sheets of tissue
project from the walls of the omasum allowing only the finest particles
to pass through
o Abomasum: microbial- true glandular stomach; HCl and pepsin are
added here, lysozymes are secreted to break down cell walls. Digestion
of microbes begin in abomasum
15. Describe how microbial digestion provides energy to the ruminant.
o
16. Describe how microbial digestion contributes protein to the ruminant.
o
17. What are the advantages of a ruminant compared to a Monogastric herbivore like
a horse?
o
18. Under what conditions is a horse more efficient than a ruminant?
19. Describe how the rumen changes as the animal matures.
o At birth the rumen is relatively small making up only 25% of the
stomach capacity. At adulthood the rumen has enlarged to make up
80% of the total stomach volume.
20. How do the relative sizes of each portion of the digestive tract reflect the type of
diet and the importance’s of microbial verse chemical digestion in the pig, horse,
and cow?
o Pig: the pig has relatively the same sizes throughout the digestive
tract. This shows that the pig is and omnivore because it consumes
both plants and animals. This is important for chemical digestion to
secrete HCl and pepsin in the stomach to break down the foods. Fore
gut fermenter
o Horse: in the horse the large intestine is significantly bigger because it
is a hind gut fermenter. This means the horse has greatly increased
the capacity for fiber digestion in the cecum and colon. Grain is
digested in the upper digestive tract (mouth, stomach, and small
intestine). “tough stuff” such as cellulose and fiber isn’t digested until
the large intestine.
o Cow: the rumen, reticulum, omasum, and abomasum are the biggest
parts of the cow. This shows that microbial digestion is done here and
where most of the digestion is done then it is absorbed in the large
intestine.
UNIT 9
1) What is meant by the terms metabolism, catabolism, and anabolism
o Metabolism: the study of all of the biochemical reactions that is
required to support normal body functions. It includes the regulation
2)
3)
4)
5)
6)
7)
8)
of those reactions by the level of substrates, metabolites, and
hormones.
o Catabolism: the breakdown of complex molecules into smaller ones.
Catabolic reactions generate energy
o Anabolism: build up complex molecules form less complex
precursors. Anabolic reactions consume energy
Define growth
o Growth is an increase in body mass. Growth is anabolic. When
anabolism exceeds catabolism the body grows. Growth requires
energy.
What is meant by the terms hypertrophy and hyperplasia? How do they differ?
o Hypertrophy: cells increase in size
o Hyperplasia cells can divide and increase in number
Describe the three types of cells: ectoderm, endoderm, and mesoderm.
o Ectoderm: forms the skin and nervous system
o Endoderm: forms the digestive tract, liver, and lungs
o Mesoderm: differentiate into stem cells that form three broad types of
tissue, the urinary and reproductive systems, the circulatory system,
and the structural components of the body.
Describe these three types of cells: adipocytes, myoblasts, and osteoblasts.
o Adipocytes: Fat cells
o Myoblasts: form muscle cells
o Osteoblasts: form bone
How are gross, digestible, metabolizable, and net energy different? Which is
better?
o Gross Energy: the total amount of energy available in feed. It is
determined by igniting the feed and combusting it completely in an
atmosphere of pure oxygen.
o Digestible Energy: subtract fecal energy from gross energy then you
have what the animal digested. This is a better estimate of what the
animal will really get from the feed than the gross energy.
o Metabolizable Energy: subtract the amount of energy lost in the urine
and in gas, we are left with metabolizable energy. Energy is loss
during these reactions in the form of heat.
o Net Energy: if you subtract the heat loss you get net energy. This is
the most precise measurement of energy content of a feed.
What is maintenance as it persists to energy metabolism
o Maintenance is breathing, pumping blood, acquisition of food,
digestion, escape, etc.
o Therefore the lungs, heart, critical muscle systems, and the brain have
high priority for glucose utilization.
What does the terms positive and negative energy balance mean?
o Positive energy balance: if the glucose coming into the blood exceeds
the maintenance requirement, then the animal is said to be in positive
energy balance. The animal can devote the excess glucose to
production. This includes growth, reproduction, and lactation.
o Negative energy balance: when animals don’t have enough glucose to
meet their maintenance requirement. They then rely on stored energy
in the body to put glucose back in the bloodstream.
9) Describe how glucose is stored during positive energy balance.
o If there is still glucose in excess of the production it can be stored. It
can be stored in the muscles, liver, and fat. In fat glucose is taken up
by adipocytes and used by them to synthesize fatty acids and glycerol.
They assemble these into triglycerides for storage.
10) Describe how glucose levels are maintained during negative energy balance
o Glycogen is the first storage form to be used. The cells that store
glycogen break down into glucose. They will use it for energy and
release the excess in the bloodstream. If negative energy balance
persists more than a day then the animal will turn to the energy
stored in fat. Lipase enzymes in the adipocytes are activated to cleave
triglycerides into free fatty acids and glycerol. Then they are released
into the bloodstream, taken up by the liver, and used to synthesize
new glucose. If the negative energy persists even further the animal
must resort to extreme measures to meet its glucose demand. Muscle
cells begin to break down muscle protein into free amino acids and
then the amino acids are released into the bloodstream.
11) Describe the embryological development of the tissues that make up the carcass
o All cells in the body are derived from undifferentiated stem cells
which then differentiate into three types of cells; ectoderm, endoderm,
and mesoderm. The structural stem cells will then differentiate into
three more types of cells; adipocytes, myoblast, and osteoblasts. Thus
the three main components of the carcass are all derived from the
same stem cell.
12) Describe how growth grate changes over time.
o At birth growth rate isn’t very efficient but at the time of weaning and
puberty this is the most efficient the growth rate will ever be. After
this time period the animals starts to get less efficient.
13) Describe how the growth rates for particular tissues changes over time.
o The central nervous system matures the most quickly reaching its
maximum growth rate just prior to birth. The skeletal system is next.
Maximum growth rate occurs in the period around weaning. The
skeletal system still grows after that but the rate is just slower. Muscle
growth is next, peaking around puberty. It is around this time that the
body gets close to its mature size. The rate of muscle cells growth
declines and the rate of fat cell growth increases.
14) Describe how the efficiency of growth changes with time
o Feed to gain ratio; this is the lbs. of feed required to produce 1 lb. of
gain. As the animal matures the feed to gain ratio will increase, this is
the amount of feed required to produce 1 lb. of gain increases. In
other words the animal becomes less efficient with age.
15) What is meant by the term compensatory growth?
o Compensatory growth is the catch up growth and compensatory gain
is an accelerated growth of the organism following a period of slowed
development, particularly as a result of nutrient deprivation.
16) Be able to give a typical birth weight, mature weight, and mature age for each of
the major livestock species.
Species
Birth Weight
Mature Weight
Mature Age
Horses
100-200
900-1100
4-5
Pigs
2-4
500-700
2-3
Sheep
6-12
80-200
2
Goats
6-10
80-220
2
Cattle
60-110
900-1800
4-5
Chickens
2 oz.
7-10
25 weeks
Turkeys
2 oz.
15-35
30 weeks
17) Be able to give the proper names for livestock animals based on their age and
sexual status
CLASSIFICATION OF “MATURE” LIVESTOCK BASED ON SEXUAL STATUS
Species
Mature
Male
Castrated
Male
(prepubertal)
Castrated Male Young
(postpubertal) Male
Mature
Female
Young
Female
Horses
Pigs
Sheep
Stallion
Boar
Ram
Gelding
Barrow
Wether
Gelding
Stag
Stag
Mare
Sow
Ewe
Goats
Cattle
Chickens
Turkeys
Buck
Bull
Rooster
Tom
Filly
Gilt
Ewe
Lamb
Doeling
Heifer
Pullet
Steer
Capon
Stag
Ram
Lamb
Bullock
Doe
Cow
Hen
Hen
AGE CLASSIFICATIONS OF YOUNG LIVESTOCK
Species
Newborn
Horses
Pigs
Sheep
Goats
Cattle
Chickens
Foal
Piglet
Lamb
Kid
Calf
Chick
Prior to
sexual
maturity
Shoat
1-2 years old
Parturition
Yearling
Yearling
Yearling
Yearling
Yearling
Foaling
Farrowing
Lambing
Kidding
Calving
Turkeys
poult
How do we know we are feeding an animal enough?
o Body condition
o Performance/ production- performance, reproduction, and lactation
How do we provide energy to animals?
o Carbohydrates
o Fats
o Protein-able to be used but not a good energy source
Good sources of energy
o Shelled corn
o Timothy hay
o Vegetable oil
o Corn silage