Transcript embryology - NorthMacAgScience

CHICK EMBRYOLOGY
WHAT ARE THE PROPER TERMS USED IN
DESCRIBING POULTRY?
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Poultry is the group name for all
domesticated birds used for meat,
eggs, or feathers.
A
baby chicken of either sex is a chick.
 A young male chicken is a cockerel.
 A castrated (neutered) male chicken
is a capon.
 A mature male chicken is a rooster.
 A young female chicken is a pullet.
 A mature female chicken is a hen.
 A group of chickens is a flock.
WHAT ARE THE PROPER TERMS USED IN
DESCRIBING POULTRY?
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A. Chickens are classified as layers or
broilers.
 Layers
are chickens used to produce large
quantities of eggs.
 On
average layer hens produce 250 to 270 eggs per
year.
 Broilers
are six- to
seven-week-old
chickens weighing
about 4 pounds that
are used for meat
because they are tender.
WHAT ARE THE DIFFERENT, BREEDS,
AND VARIETIES OF CHICKENS?
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We have two breeds of chicken in our incubator:
1. The White Leghorn.
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The Leghorn is the most popular layer breed in the United
States.
This breed is also known for its ability to take flight.
Leghorns produce white eggs.
They express yellow skin, yellow shanks, white earlobes, and
reddish-bay eyes.
They are somewhat smaller than most breeds, and tend to be
noisy.
The chicks are white in color.
WHAT ARE THE DIFFERENT, BREEDS,
AND VARIETIES OF CHICKENS?
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2. Rhode Island Red
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The Rhode Island Red is a dual-purpose breed; that is, it is
raised for meat and eggs.
The breed is dark red and lays brown eggs.
Rhode Island Reds have yellow skin, yellow shanks, red
earlobes, and reddish-bay eyes.
Chicks are a light red to tan color with two dark brown bars
running down their backs.
HOW DOES THE PROCESS OF FERTILIZATION TAKE
PLACE IN A CHICKEN EGG?
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The yolk is released into the oviduct (a long, spiraling tube in
the hen's reproductive system), where it can be fertilized
internally (inside the hen) by a sperm.
Fertilization of a chicken egg takes place when the sperm
unites with the egg, forming the blastoderm.
Unfertilized eggs will go through the same process however,
it will form a blastodisc.
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A blastodisc will not be a dark white
Not symmetrically round
Can an un-fertilized egg develop an embryo?
CAN AN UNFERTILIZED EGG ACTUALLY
DEVELOP?
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Parthenogenesis is an inherited trait that
causes the development of unfertilized eggs.
 About
1% of parthenogenetic embryos will develop
and hatch with deformities.
 Parthenogenesis is more common in turkeys than
in chickens.
WHAT ARE THE INTERNAL PARTS OF AN EGG
AND WHAT ARE THEIR FUNCTIONS?
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1. Blastoderm/blastodisc
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2. Yolk: Produced by the hen's ovary in a process called
ovulation.
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It is the yellow, inner part of the egg where the embryo will form.
The yolk contains the food that will nourish the embryo as it grows.
WHAT ARE THE INTERNAL PARTS OF AN EGG AND
WHAT ARE THEIR FUNCTIONS?
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3. Vitelline (yolk) membrane - the membrane that surrounds
the yolk.
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4. Thick albumin - the stringy part of the egg white (albumin)
located nearest the yolk.
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5. Thin albumin - the watery part of the egg white (albumin)
located farthest from the yolk.
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6. Chalaza - a spiral, rope-like strand that anchors the yolk in
the thick egg white. There are two chalazae anchoring each
yolk, one on the top and one on the bottom.
WHAT ARE THE INTERNAL PARTS OF AN EGG
AND WHAT ARE THEIR FUNCTIONS?
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7. Inner shell membrane - the thin membrane located between the
outer shell membrane and the albumin.
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8. Outer shell membrane - the thin membrane located just inside the
shell.
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9. Air cell - an empty space located at the large end of the egg; it is
between the inner and outer shell membranes.
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10. Shell - the hard, protective coating of the egg.
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It is semi-permeable; it lets gas exchange occur, but keeps other substances
from entering the egg.
The shell is made of calcium carbonate.
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Label the Chick Egg
WHAT IS THE IDEAL ENVIRONMENT FOR INCUBATING
EGGS ARTIFICIALLY?
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Four Factors must be present for ideal incubation
conditions:
A. Temperature. Optimum temperature for hatching
chickens is between 99 and 100 degrees F.
B. Humidity. Eggs lose moisture during development
and low humidity causes an increased loss. High
humidity can prevent the correct evaporation of water.
WHAT IS THE IDEAL ENVIRONMENT FOR
INCUBATING EGGS ARTIFICIALLY?
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C. Ventilation. Proper circulation is critical to assure a
fresh supply of oxygen and removal of carbon dioxide.
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D. Position and turning of eggs. The head of the chick
must face the large end of the egg for proper hatching.
Eggs should be incubated large end up, and turned three
to five times daily to prevent the developing embryo from
attaching to the shell membrane.
HOW DO WE PREPARE EGGS FOR HATCHING AND CARE
FOR YOUNG BIRDS DURING BROODING?
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Fertility of eggs can be determined by a process known as
candling.
A. Eggs held up to an egg candler, a device for shining a light
beam into an egg. Eggs will look different depending on
fertilization or lack of fertilization. Fertile eggs will appear
darker as the developing embryo begins to form. Infertile eggs
can be detected after 15 to 18 hours of incubation.
Between the following poultry species, who has
the longest incubation period? Shortest?
WHY?
-
Duck
Pigeon
Ostrich
Chicken
Turkey
HOW DO WE PREPARE EGGS FOR HATCHING AND CARE
FOR YOUNG BIRDS DURING BROODING?
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Different breeds of poultry have different
incubation lengths:
Bird:
Incubation:
Chickens
21 days
Ducks/Turkeys
28 days
Pigeon
18 days
Ostrich
42 days
Do not candle or turn the eggs the last three
days of incubation.
CHICK DEVELOPMENT
DAY 1
 18 hours – the digestive system starts to
appear
 20 hours – the vertebral column starts to
appear
 21 hours – the nervous system and brain
begin to form
 22 hours – the head begins to form
 23 hours – the extraembryonic blood
systems begin to form
 24 hours – the eyes begin to form
DAY 2
 25 hours – the heart begins to form
 35 hours – the ear pits begin to form
 37 hours – the amnion starts to appear
 42 hours – the heart starts to beat
 46 hours – the throat begins to form
CHICK DEVELOPMENT
DAY 3
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50 hours – the amnion begins to
form
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60 hours – the nose begins to form
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62 hours – the legs start to appear
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64 hours – the wings start to appear
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70 hours – the allantois begins to
form
Day 4
•The tongue begins to form
•The tail appears
•The toes begin to form
•Extra-embryonic
circulation is fully
functional
DAY 5
- The crop begins to form
- The bones of the legs begin
to form
- The sex of the chick is
determined and its
reproductive organs begin to
form(ovary & oviduct for the
female as studied
in Part III)
CHICK DEVELOPMENT
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Day 6
The beak and egg-tooth begin to
form
The ribs start to appear
The gizzard begins to form
Voluntary movement begins
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Day 7
The wings bend at the elbow
and the leg at the knee
The toes are visible
The abdomen is bigger as
the intestine starts to loop
CHICK DEVELOPMENT
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Day 8
The feathers begin to form
The eye lids begins to form
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Day 9
The mouth opening
appears
The claws begin to form
CHICK DEVELOPMENT
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Day 10
The beak starts to harden
The comb is visible
The flight feathers develop
Day 11
The toe claws begin to curve
downwards
The bottom of the feet become
padded
The chick begins to take calcium
from the eggshell
CHICK DEVELOPMENT
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Day 12
Scales appear on the lower legs
The chick continues to grow and
move
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Day 13
Body fairly well covered with
feathers
The left and right collar bones join
to form the wishbone
CHICK DEVELOPMENT
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Day 14
The embryo turns its head
towards
the large end of the egg
The skull and ribs have begun
to ossify
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Day 15
The scales, claws and beak
are becoming firm
CHICK DEVELOPMENT
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Day 16
The chick is fully covered
with feathers
The albumen is nearly gone
and the yolk
is increasingly important as
nourishment
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Day 17
The chick turns its beak
towards the air cell
and begins preparation for
hatching
CHICK DEVELOPMENT
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Day 18
The growth of the embryo
is nearly complete
The amnion which
protects the chick
begins to disappear
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Day 19
The yolk sac begins to
enter the body
The chick occupies all
the space in the egg
except the air cell
CHICK DEVELOPMENT
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Day 20
The yolk sac is
completely drawn into
the body
The beak breaks
through the inner shell
membrane
The lungs begin to
function and to use the
air cell for breathing
The allantois ceases to
function and starts to
dry up
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Day 21
The neck begins to jerk
The egg tooth pips
through the shell
The chick hatches!
HOW THE CHICK HATCHES
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When the chick is
completely out of
the shell it lies still.
It is extremely tired.
After a rest it
begins to rise to its
feet and gain
coordination.
Within a few days
the egg tooth will
disappear.
WHAT IS THE PROCESS OF CHICK DEVELOPMENT DURING
INCUBATION?
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Day 3:
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Day 6
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Body parts have begun to for
The embryo will have a distinct question mark shape
Heart begins to beat
Voluntary movement begins
formation of reproductive organs and differentiation of sex
Day 9
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Egg tooth begins to form
Body parts can be clearly recognized
WHAT IS THE PROCESS OF CHICK DEVELOPMENT DURING
INCUBATION?
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Day 12
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Day 16
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Beginning of feathers
Beak, claws become to harden
Embryo continues to grow and moves into position to break
the shell
Day 20-21
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yolk sac completely drawn into body cavity;
embryo occupies practically all the space within the egg
except the air cell
When the air cell is broken, the embryo only has a limited
time to pip its way out of the egg.
WHAT IS THE PROCESS OF CHICK DEVELOPMENT DURING
INCUBATION?
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http://www.youtube.com/watch?v=tof5b1Qs_OE&feature=related
HOW DO WE PREPARE EGGS FOR HATCHING AND CARE
FOR YOUNG BIRDS DURING BROODING?
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D. Brooding refers to the care of young poultry from the time of hatching through
eight to ten weeks of age.
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Chicks should be removed from the incubator when they have dried and the
down becomes fluffed. This drying normally takes about 12 hours.
1. Certain environmental conditions are needed for proper brooding.
 a. Temperature—When chicks are one day old, the temperature
should be between 90 and 95 degrees F. The temperature is
generally lowered five degrees per week until a temperature of 70 to
75 degrees is reached, or until the chicks are fully feathered.
 b. Ventilation—Proper ventilation provides fresh oxygen, removes
carbon dioxide, carbon monoxide, ammonia, and keeps bedding dry.
 c. Moisture—50 to 60% relative humidity is recommended for good
feathering.
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