How Does a Rooster Fertilize an Egg / DIY Science Project


How Does a Rooster Fertilize an egg

How Does a Rooster Impregnate a Chicken

The completed mating in chickens is the culmination of a sequence of behaviors. The rooster will initiate mating by exhibiting courtship behavior: dropping one wing and dancing in a circle (the lowered wing will be on the inside of the circle dance). The hen will crouch (dip her head and body) to indicate receptiveness to the male. The rooster will then mount the hen and grab her comb, neck feathers, or the skin on the back of her head or neck to help hold onto the hen’s back.

The next behavior is the tread (the rooster walks quickly in place on the hen’s back) and finally the completed mating of the behavioral sequence. The completed mating occurs when the rooster dips his tail to the side of the hen’s tail and spreads his tail feathers so that their cloacae come into contact.

At this point, the rooster’s ejaculate is released directly into the hen’s vagina via her cloaca. In the typical breeder house with thousands of birds, the entire sequence of behaviors does not always occur, and the courtship dance is frequently left out of the sequence.

Rooster Mating

Chickens are polygynous but certain males and females selectively mate regularly.

Some females in the flock will show avoidance to specific males, and therefore are rarely mated by those males.

The rooster usually ejaculates between 100 million and five billion sperm at a time with greater concentrations produced at the beginning than at the end of the day, when depletion occurs after many mating.

The first ejaculates average about 1 ml but after several ejaculations, the average volume will be reduced to 0.5 ml or less. These data were obtained from semen collection as done in artificial insemination. The numbers of sperm per ejaculate and the volumes of semen should be lower in natural mating than semen collection by artificial stimulation and abdominal massage.

The frequency of mating follows a diurnal pattern with mating frequency reaching peaks early and late in the day.

Roosters Can Mate 10 – 30 Times a Day


A rooster may mate from 10 to 30 or more times per day, depending on the availability of hens and competition from other roosters.

However, the number of sperm per ejaculate is seldom less than 100 million which is the minimum required to maintain high fertility. With natural mating, better fertility will result when mating occurs after the hen has laid a hard-shell egg.

However, if the hens are mated frequently (daily), there is unlikely to be a noticeable difference in fertility regardless of when the mating occurs.

The rooster has a small phallus that becomes engorged with lymph to form a copulatory organ. The copulatory organ is rudimentary and at the time of mating, there is practically no penetration.

The hen everts her vagina during copulation, which helps to transfer the semen into the oviduct.

Ducks, geese, and some other birds have more well-defined copulatory organs.


An understanding of the natural mating behavior in chickens can help the breeder manager and producer to observe the mating behavior sequences in their flocks to assess whether their flock fertility should be good, average, or poor. Since mating behavior generally follows a diurnal pattern, the best times to observe the flock for mating behavior are early in the morning and late in the afternoon.

In a broiler breeder house, pay attention to the frequency of females coming off the slats so that they can be mated. When a large percentage of females is reluctant to enter the litter area, it is a sign that the males may be overly aggressive and fertility will suffer.

A good practice would be to walk the outside perimeter of the slats in the time before and shortly after egg production begins. This forces the hens to move toward nests and to become accustomed to the litter area.

Fertilization and Early Development

Fertilization of the germinal disc by the sperm takes place in the infundibulum about 15 minutes after its holding follicle has released the yolk.

Cell division to create the new embryo starts about five hours after fertilization and continues while the egg passes along the oviduct and after the egg is laid.

It is generally said that the hen’s egg takes 21 days of favorable incubation conditions for the chicken to develop and hatch. However, this development takes 22 days – one day in the oviduct and 21 days in the incubator or nest.

How a Chicken Makes an Egg

The zygote

When the sperm cell (with half the required chromosomes) fertilizes the female egg cell (with the other half of the required chromosomes) it forms the zygote, which is a single cell with the correct number of chromosomes.

About five hours after fertilization the zygote enters the isthmus and it is here that the new embryo starts to develop by simple cell division. By the time the egg leaves the isthmus, the zygote, now called the blastoderm or embryo, comprises eight cells and after four hours in the uterus, it has grown to 256.

Formation of Ectoderm, Endoderm and Mesoderm

Initially, the dividing cells form one layer over the yolk, but as cell division continues two layers are formed. These are called the ectoderm (uppermost) and the endoderm (underneath) layers.

At about this stage the central cells of the blastoderm separate from their contact with the yolk to form a cavity. It is in this cavity that subsequent embryo development occurs.

Soon after the formation of the ectoderm and endoderm, the third layer of cells called the mesoderm, or middle layer, is formed.

From this stage on, the organs and tissues of the bird will develop from these three layers of cells.

  • The ectoderm produces the nervous system, parts of the eyes, the feathers, beak, claws, and skin.
  • The endoderm produces the respiratory system, the digestive system, and secretory organs.
  • The mesoderm produces the skeleton, muscles, circulatory system, reproductive organs, and excretory system.

Another important development at this stage is the way the cells change to allow the production of the different types of cells that make up the tissues. By the time the egg is laid the embryo consists of many cells differentiating into the various tissues, organs, and body systems.

Baby Chicken Development in Egg

Physiological zero

The fowl retains some vestiges of the characteristics of its reptilian ancestors. One characteristic in particular is the influence of ambient temperature during the post laying period on embryonic development.

When the temperature of the egg is below 20°C, the embryo becomes dormant and most development stops. When the temperature rises above 20°C, embryonic activity re-initiates. This temperature of about 20°C when the embryonic activity starts or stops is often referred to as a physiological zero.

Fluctuating temperatures above/below 68°F will create a start/stop response in embryonic development, and each succeeding response progressively weakens the embryo. The temperature must be increased to the required 37-38°C for optimum development to occur.

Failure to satisfy this need leads to significantly weaker embryos. To retain maximum viability of the embryo, hatching eggs should be processed and placed in cool storage below 68°F as soon as possible after collection and held at that temperature until the pre-warming process just prior to setting the eggs in the incubator.

Once in the incubator, the temperature must be controlled within very close parameters.

Extra-embryonic Membranes

Because the avian embryo has no anatomical connection to the hen, all of its nutritive requirements, except oxygen, must be contained within the egg. From very early on, the embryo develops special membranes external to its body to access the nutrients in the egg and to carry out essential bodily functions.

There are four of these special membranes and their names and functions are as follows:

Yolk sac: This sac envelops the yolk and produces an enzyme that changes the yolk material into a form that can be used as a food source by the developing embryo. Any remaining, unused yolk material in the yolk sac when the chicken hatches from the egg are drawn into the abdomen for use by the chicken for the first two to three days after hatching while the chicken learns what to eat/drink and where to find it.

Amnion: The amnion forms a sac that is filled with fluid in which the embryo floats. In this way, it provides a shock-absorbing environment in which the fragile embryo can develop without harm from normal day to day knocks.

Allantois: The allantois develops an extensive circulatory system connected to that of the embryo and is driven by the new embryonic heart. When the allantois is fully developed it completely surrounds the embryo. This membrane has a number of functions:

  • Respiratory – the developing embryo uses oxygen and produces carbon dioxide (it respires). It is unable to carry out this function for itself and hence the allantois oxygenates the blood and eliminates carbon dioxide.
  • Excretory – it removes the wastes that result from the embryo’s metabolism and deposits it in the allantoic cavity.
  • Digestive – it provides the means for the embryo to access the albumen and the calcium of the shell.

Chorion: The chorion fuses the inner shell membrane to the allantois and helps that membrane to carry out its functions.

Daily embryonic development

To better carry out an investigation into poor hatchability it is necessary to have knowledge of the way the embryo develops from day today. This allows the hatchery manager to determine at what age/stage embryos may have died. This is important information when attempting to identify the cause of any poor results.

Photographs of the following steps may be viewed by Clicking Here.

DAY 1: Appearance of embryonic tissue.

DAY 2: Tissue development very visible. Appearance of blood vessels.

DAY 3: Heart beats. Blood vessels very visible.

DAY 4: Eye pigmented.

DAY 5: Appearance of elbows and knees.

DAY 6: Appearance of beak. Voluntary movements begin.

DAY 7: Comb growth begins. Egg tooth begins to appear.

DAY 8: Feather tracts seen. Upper and lower beak equal in length.

DAY 9: Embryo starts to look bird-like. Mouth opening occurs.

DAY 10: Egg tooth prominent. Toe nails visible.

DAY 11: Cob serrated. Tail feathers apparent.

DAY 12: Toes fully formed. First few visible feathers.

DAY 13: Appearance of scales. Body covered lightly with feathers.

DAY 14: Embryo turns head towards large end of egg.

DAY 15: Gut is drawn into abdominal cavity.

DAY 16: Feathers cover complete body. Albumen nearly gone.

DAY 17: Amniotic fluid decreases. Head is between legs.

DAY 18: Growth of embryo nearly complete. Yolk sac remains outside of the embryo. The Head is under right-wing.

DAY 19: Yolk sac draws into the body cavity. Amniotic fluid is gone. Embryo occupies most of the space within the egg (not in the air cell).

DAY 20: Yolk sac is drawn completely into the body. The embryo becomes a chick (breathing air with its lungs). Internal and external pipping occurs.

Embryonic Communication

With natural incubation, the chicks hatch over a relatively short period of time. This is despite the eggs being laid in the nest over a period of several days and the hen sitting on different eggs for different periods of time.

Synchronized Hatching

This indicates that there is some system to synchronize the hatching process. It is now known that the different embryos communicate with each other by a series of clicking sounds, the rate of clicking being the important feature.

How Chicks get Oxygen / Clicking Communication

Ensuring the eggs on the hatching trays are in contact with each other facilitates the synchronization of hatching where the eggs are incubated in a modern machine. This helps to reduce the time between when the first and last chicks hatch.

DIY Science Project Watch a Chick Develop

DIY Science Experiment Watch Development of Egg – Chick

Rooster Care and Feeding

Before you add a male bird to your backyard flock, weigh the pros and cons, and be prepared to manage him differently than your hens.

Are Roosters Aggressive?

A rooster’s instinct is to protect the flock and help ensure hens are well taken care of. Many take this job very seriously. Unfortunately, the rooster’s methodologies are not always friendly.

He may view you, your children, or other pets as a threat to the flock and act hostilely to protect the hens. Behavioral training can help, but sometimes you just need to find a mellow rooster.

At night, it may help to keep roosters in a separate coop away from the hens. Crowing and aggression can sometimes be reduced this way.

Are There Rooster Breed Differences?

In general, some breeds have a reputation for producing more docile roosters than others. These include the Langshan, Silkies, Brahma, and Cochin. Leghorns, Barred Rocks, Rhode, and Island Reds are typically more active.

Roosters raised from the time they hatch are sometimes more docile. Aggressive behaviors are also lessened when hens are not present; however, there are no guarantees on how a bird will behave with maturity.

So Why Keep a Rooster?

Roosters are good protectors and can earn their keep when you have a large area in which your hens free-range. Roosters will also seek out and alert hens of the best food find and tasty treats.

If you wish to breed your hens and hatch baby chicks from your flock, a rooster is required to fertilize the eggs. Aesthetically, roosters are quite stunning, with their long, colorful feathers and stately presence. A rooster need not be present for hens to lay eggs, but you will need a rooster if breeding for live chicks is a goal.

How Many Roosters?

To prevent fighting, consider owning just one rooster. Keeping multiple roosters is usually not recommended unless you have a large flock of hens or no hens at all. One rooster per 10 hens is a rule of thumb.

This will help prevent over-breeding. If you have a rooster and fewer than 10 hens, consider housing the rooster separately. Always have a game plan for how to deal with a rooster that does not fit in with your flock or family. Re-homing an aggressive rooster can be challenging, so have a plan before you get the rooster.

Family Sized Chicken Farm Egg Calculator

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How Many Chickens Do I need to Provide Eggs For my Family
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Rare Breed Chicken Farming

Rare BreedsCountry of OriginEggs/WeekAverage WeightPrice / Chicks
Black PenedesencaSpain3-44-5lbs$ 13.43
Black SumatraSumatra4 / Tinted in Color4lbs$ 4.56
AmeraucanaUnited States / Chile3 / 4 Blue5 lbs$ 4.25
Lavender OrpingtonEngland4 / 5 Brown 5 lbs$ 6.08
Partridge ChanteclerCanada3-5 / Brown7 lbs
WyandotteUnited States3 - 5 / Tinted Brown6 lbs$ 4.90
WelsummerWelsum Netherlands4 / Dark Brown5 lbs$ 5.95
Silver Grey DorkingUK / Roman8 lbs$ 5.95
Light BrahmaUnited States / ChinaBrown13 lbs$ 4.90
Silver Laced Cochin / ShanghaiChina5-6 / Brown6 lbs$ 4.90
White MaransMarans / France4 / Dark Brown5 lbs$ 6.08
DominiquesUnited States4 - 5 / Brown 7 lbs$ 4.90
Exchequer LeghornTuscany ItalyWhite5 lbs$ 4.25
Silver Spangled Appenzeller
Spitzhaubens
Switzerland54 lbs
Buff Brahma StandardShanghai ChinaBrown13 lbs$ 4.90
Silver Laced PolishPoland / Netherlands4-5 lbs$ 5.95
White Sultan / Fowls of the SultanTurkey2 - 3 / White 4-6 lbs$ 7.75
Mottled HoudanHoudan Paris FranceWhite4 - 5 lbs$ 7.75
Dong Tao / Dragon ChickenVietnam2/3$ 2500 -
Ayam CemaniIndonesia3 / Cream 5 lbs$ 50 - $ 2500
Onagadori / Honorable ChickenJapan$ 49.00
PolveraraItaly2 / 3
IxworthSussex UK4 / Cream
Naked Neck / Transylvanian Naked-Neck chickens.Transylvania5$ 4.25
CampaignBelgium7 / White5 lbs$ 7.75 / Golden
Deathlayer / German7 / White$ 99.00
Serama / Smallest Chicken in the WorldThailand.5 - 1 Lb$ 39.00
Silkie / SilkyChinese2 / Cream$ 5.75 / White $ 5.75 / Blue $ 5.75 / Buff
$ 5.75 / Black
Pricing is buying 1 Chick - Bulk gives better prices - they are also only available during a special date ranges

Types of Chicken Breeds

Chicken BreedsOriginMeat/ Layers / Dual PurposeFinished WeightEggs per WeekWeeks to Slaughter
Broilers
Canada/US/EuropeMeat3.3 lbs514 Weeks
Cornish crossesEnglandMeat6.5 - 8.5 lbs38 - 9 Weeks
Jersey GiantsUSAMeat ( Intended to replace Turkeys)13 lbs48 - 9 Months
Hertigage Breeds6 - 9 months
DelawareUSA DelawareDuo6.5 lbs4 - large8 Months
DorkingUnited KingdomDuo10 - 14 lbs5 - med5 Months
BuckeyeUSA OhioDuo6 - 9 lbs4 - med5 Months
Rhode Island RedUSA Rhode Island Duo6 b- 8 lbs5-65 Months
LeghornItalyEggs4 -5 lbs48 Months
Plymouth RockUSA - MassachusettsDuo7.5 lbs45 Months
SussexUnited KingdomDuo7 lbs4 - 5 - large5 Months
WyandotteCanadaDuo7 - 9 lbs5 Months
WelsummerNetherlandsDuo7 lbs4 / Week5 Months
HamburgUnited KingdomEggs7 lb4 - med9 weeks
Black AustralorpAustraliaDuo\3 - 5 lb5 - med5 months
Buff OrpingtonEngland Duo7 - 8 Lbs4 - 58 months
BrahmaMeat11 lbs3 - med5 monthss
Name of Breed
Origin
Meat Breeds
Laying Breeds
Dual Purpose Breeds

Chicken / Poultry Breeder Associations

Rabbit AssociationLocationLink
US Poultry & Egg AssociationUnited StatesUSPA
American Poultry AssociationCaliforniaAPA
Ohio Poultry AssociationOhioOPA
National Chicken CouncilUnited StatesNCC
British Poultry CouncilUnited KingdomBPCE
Poultry Club of Great BritainUnited KingdomPCGB
Association of Poultry Breeders in EUEuropeAVEC
Australian Chicken Meat Federation IncAustraliaACMF
Australian Poultry HubAustraliaPoultry Hub

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