embryology - NorthMacAgScience
CHICK EMBRYOLOGY
WHAT ARE THE PROPER TERMS USED IN
DESCRIBING POULTRY?
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?
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?
We have two breeds of chicken in our incubator:
1. The White Leghorn.
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?
2. Rhode Island Red
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?
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.
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?
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?
1. Blastoderm/blastodisc
2. Yolk: Produced by the hen's ovary in a process called ovulation.
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?
3. Vitelline (yolk) membrane - the membrane that surrounds the yolk.
4. Thick albumin - the stringy part of the egg white (albumin) located nearest the yolk.
5. Thin albumin - the watery part of the egg white (albumin) located farthest from the yolk.
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?
7. Inner shell membrane - the thin membrane located between the outer shell membrane and the albumin.
8. Outer shell membrane - the thin membrane located just inside the shell.
9. Air cell - an empty space located at the large end of the egg; it is between the inner and outer shell membranes.
10. Shell - the hard, protective coating of the egg.
It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg.
The shell is made of calcium carbonate.
Label the Chick Egg
WHAT IS THE IDEAL ENVIRONMENT FOR INCUBATING
EGGS ARTIFICIALLY?
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?
C. Ventilation. Proper circulation is critical to assure a fresh supply of oxygen and removal of carbon dioxide.
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?
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?
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-
-
-
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Duck
Pigeon
Ostrich
Chicken
Turkey
HOW DO WE PREPARE EGGS FOR HATCHING AND CARE
FOR YOUNG BIRDS DURING BROODING?
Different breeds of poultry have different incubation lengths:
Bird:
Chickens
Ducks/Turkeys
Pigeon
Ostrich
Incubation:
21 days
28 days
18 days
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
50 hours – the amnion begins to form
60 hours – the nose begins to form
62 hours – the legs start to appear
64 hours – the wings start to appear
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
Day 6
The beak and egg-tooth begin to form
The ribs start to appear
The gizzard begins to form
Voluntary movement begins
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
Day 8
The feathers begin to form
The eye lids begins to form
Day 9
The mouth opening appears
The claws begin to form
CHICK DEVELOPMENT
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
Day 10
The beak starts to harden
The comb is visible
The flight feathers develop
CHICK DEVELOPMENT
Day 12
Scales appear on the lower legs
The chick continues to grow and move
Day 13
Body fairly well covered with feathers
The left and right collar bones join to form the wishbone
CHICK DEVELOPMENT
Day 14
The embryo turns its head towards the large end of the egg
The skull and ribs have begun to ossify
Day 15
The scales, claws and beak are becoming firm
CHICK DEVELOPMENT
Day 16
The chick is fully covered with feathers
The albumen is nearly gone and the yolk is increasingly important as nourishment
Day 17
The chick turns its beak towards the air cell and begins preparation for hatching
CHICK DEVELOPMENT
Day 18
The growth of the embryo is nearly complete
The amnion which protects the chick begins to disappear
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
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
Day 21
The neck begins to jerk
The egg tooth pips through the shell
The chick hatches!
HOW THE CHICK HATCHES
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?
Day 3:
Body parts have begun to for
The embryo will have a distinct question mark shape
Heart begins to beat
Day 6
Voluntary movement begins formation of reproductive organs and differentiation of sex
Day 9
Egg tooth begins to form
Body parts can be clearly recognized
WHAT IS THE PROCESS OF CHICK DEVELOPMENT DURING
INCUBATION?
Day 12
Beginning of feathers
Day 16
Beak, claws become to harden
Embryo continues to grow and moves into position to break the shell
Day 20-21
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?
http://www.youtube.com/watch?v=tof5b1Qs_OE&feature=related
HOW DO WE PREPARE EGGS FOR HATCHING AND CARE
FOR YOUNG BIRDS DURING BROODING?
D. Brooding refers to the care of young poultry from the time of hatching through eight to ten weeks of age.
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.
