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?

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:

Do not candle or turn the eggs the last three days of incubation.

Bird: Incubation:Chickens 21 daysDucks/Turkeys 28 daysPigeon 18 days Ostrich 42 days

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 itsreproductive organs begin to form(ovary & oviduct for the female as studiedin 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 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 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 DEVELOPMENTDay 20The 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 21The neck begins to jerkThe egg tooth pips

through the shellThe 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.