Collection and storage of hatching eggs

When collecting hatching eggs, care must be taken not only because of the possibility of damaging the integrity of the shell. It must be taken from the nest with two fingers (thumb and index) by opposite ends, so as not to erase the super-shell film - the cuticle - from the shell.

It is better to collect eggs in wicker baskets or special trays, placing them with the sharp end down. Eggs must be collected several times a day to prevent excessive contamination. In winter, eggs should be collected more often - every hour and a half, avoiding hypothermia.

It should be taken into account that chickens and turkeys lay eggs more intensively in the first half of the day and finish by 15-16 hours.

Waterfowl have a different feature of oviposition. It starts at 2-3 am and ends at 10-12 am. With this in mind, it is necessary to collect eggs. Until the end of laying

It is undesirable to release waterfowl for unlimited and aquatic ranges; eggs may be missing.

Care should also be taken when transporting eggs to the place of storage or incubation. Bumpy roads and rough transport will lead to fighting, pinching, notching of eggs, breaking of hailstones, displacement of the yolk, air chamber and, ultimately, a decrease in hatchability.

It is highly undesirable to wash contaminated eggs. Washing causes clogging of pores and infection with pathogenic microflora, molding and loss of incubation qualities. In addition, during the washing period the protective film is thoroughly washed off. Therefore, contamination of eggs must be prevented by timely cleaning of nests, renewal, drying and removal of contaminated litter.

Lightly contaminated eggs can be dipped (not washed!) in a 2% sodium hydroxide solution or a 0.5% formaldehyde solution. The remaining dirt can be scraped off with a thin brush.

Before being placed in the incubator, eggs must be stored in special rooms (in farms - in warehouses).

The premises must be equipped with psychrometers and a thermometer. The optimal conditions for storing eggs are considered to be a temperature of 8-

12'C and relative humidity 70-75%. Store eggs refrigerated.

High temperatures are also detrimental to eggs. At a temperature slightly above 20°C, defective development of the embryo begins, followed by death.

The egg, as already noted, must be stored with the sharp end down in the cells. When stored with the blunt end facing down, the pressure of the contents on the air chamber shell may cause it to become dislodged and possibly dislodge the yolk.

Low air humidity in the room where the egg is stored leads to increased shrinkage, loss of moisture from the protein and, as a result, to an underestimated hatch. Long-term storage of eggs before placing them in the incubator reduces their quality and hatchability with each subsequent day.

How to properly store a hatching egg: necessary conditions

The main thing when storing incubation material is to maintain the temperature and humidity at a certain level. For each type these indicators are individual:

  • chicken: temperature - +8-12°C, humidity - 75-80%;
  • goose: temperature - +12-15°C, humidity - 78-80%;
  • duck: temperature - +15-18°C, humidity - 78-80%;
  • guinea fowl: temperature - +8-12°C, humidity - 80-85%;
  • quail: temperature - +12-13°C, humidity - 60-80%;
  • turkey: temperature - +15-18°C, humidity - 75-80%;
  • ostrich: temperature - +16-18°C, humidity - 75-80%.

As you can see, the average optimal storage temperature is 8-12°C, and humidity is 75-80%.

The room where the eggs will be stored must be equipped with control and measuring instruments (preferably more than one). It must have good ventilation and clean air, since foreign odors easily penetrate the shell. Drafts are unacceptable, as they accelerate the process of evaporation of moisture from the surface of the shell.

It is best to install racks indoors on which boxes with incubation material will be placed. It is advisable to divide the boxes into cells using thin boards or cardboard. The cell size should correspond to the size of the egg. You can use cardboard pallets for storage, in which the product is sold in stores.

In the cells, the incubation material should be placed with the sharp end up or horizontally.

For long-term storage you need:

  • warm up the incubation material every 5 days for 5 hours, after warming up, return to normal conditions;
  • place the product in polyethylene filled with nitrogen;
  • Install an ozonizer in the storage facility and maintain the ozone concentration at 2-3 mg per cubic meter.

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Shelf life of eggs

Acceptable storage periods for eggs under recommended conditions - chicken

- up to five days, turkey - up to seven, goose and duck - up to eight.

We have already noted that the color of the yolk does not always indicate the saturation of provitamin A and good hatchability.

The air chamber of the egg (puga) is directly related to the hatching of an already formed embryo and serves as its initial source of oxygen even before hatching. Not finding it before pecking (breaking the shell), the young animals die, suffocating. Therefore, it is extremely important to select eggs with an air chamber at its blunt end (location of the embryo's head). If the chamber is on the side or at the sharp end, the egg is discarded, as are those whose chamber moves or trembles when it is moved.

The size of the air chamber can indicate the age of the egg. For chicken hatching eggs, the height of the air chamber should not exceed 1.5-2 mm, for turkey and duck eggs 3.0-3.5 mm, for goose eggs 3.5-4.0 mm, for guinea fowl eggs - 1.5 mm.

Which samples are suitable for incubation?

To achieve a positive result, strict control in the selection process is necessary. Eggs must meet certain criteria.

  • Mass and shape. Heavy samples are not suitable. The ideal weight is approximately 50-75 grams. If the mass is excessive, there is a high probability of developing two yolks. Samples with such a deviation are not suitable.

  • Shell. The shell must be perfectly smooth, no cracks or dents. The presence of colored spots on the shell indicates the appearance of decomposition. Dirty eggs should not be used and cleaning is not recommended. This is due to the risk of damage to the protection layer.
  • Yolk. It should be free of any particles or stains. It should be in the center of the egg.
  • Air chamber. Even at the moment of rotation, it must remain in the wide part, not adjacent to the walls. Its diameter should not exceed 15 mm, and its thickness should be about 2 mm.

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Only the coincidence of these criteria allows the samples to be used for incubation.


Fertilization is the main condition for hatching eggs. But it is impossible to determine this sign in advance. Although a method of electrical measurements for fertilization has been developed, it has not found application in practice.

Currently, the state of fertilization is determined by viewing eggs on an ovoscope on the 4-7th day of incubation. A seized unfertilized egg is only suitable for livestock and poultry feed.

The permissible level of egg fertilization for chickens of egg breeds is 93%, meat - 90%, turkeys, light breed ducks - 90%, heavy breeds - 85%, geese - 65%, guinea fowl - 70%.

Environmental factors in embryo development

For the development of the embryo, environmental factors are necessary that can have a beneficial effect on it.

The main such factors are optimal temperature and humidity, air exchange and regular turning of eggs.

A reasonable combination of these factors together determines the incubation mode.

In the first week of incubation of chickens, an environment of slightly elevated temperature and maximum retention of water in the egg white is considered favorable. Closer to the middle of incubation, it is necessary to create conditions for the evaporation of water from the allantois. In the last third of incubation, a regime for removing excess heat is necessary, since during this period there is an increased formation of heat in the egg. The need for additional heating with electric heaters is sharply reduced; increased heat removal from the chamber and increased air circulation are required (the oxygen requirement of the embryo increases).

Maintaining the temperature in the incubator can be done in two ways, depending on the freshness of the eggs laid for incubation. The first method: maintaining the temperature exclusively using electric heaters is when a batch of eggs of the same age is incubated in a cabinet. If batches of different ages are to be incubated, they are laid in stages. Trays of subsequent batches are placed between tiers with earlier ones, which, due to their age, have a slightly higher temperature and are able to radiate it to a cold egg.

During the hatching period and during hatching, the temperature inside the egg rises even more, and the embryo does not require as much heat. It needs higher humidity more. The heat transfer of the egg can be enhanced by increasing the air flow rate.

How and when to remove eggs from the nest

Before inspecting chicken eggs, it is important to determine their suitability for placing in the incubator.

To obtain healthy offspring, several conditions must be met:

  1. Take a product obtained naturally from a laying hen that was fed natural feed without additives that stimulate egg production.
  2. The condition of the embryo is negatively affected by light provocation: a forced increase in the duration of daylight hours. When breeding purebred chickens, it is important that natural conditions are created for laying hens.
  3. Before the start of the planned selection of eggs, chickens are given B vitamins, which, being in the white and yolk, increase the hatchability rate.
  4. Eggs are taken from nests at least twice a day. This is especially important to observe in the summer, which will prevent the loss of incubation qualities of the products.
  5. It is optimal to collect eggs from a laying hen immediately after laying, while it is warm.

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In modern industrial cabinet-type incubators, the optimal temperature is maintained within 37-38°C.

The embryo begins its development when it is heated to 37-43 “C. It is known that at the beginning of incubation the embryo actively responds to increased heating: metabolism in its cells significantly increases and growth increases. It grows especially intensively in the first day: its mass increases more than tenfold. Therefore, it is very important to reach the specified temperature regime as quickly as possible. The warm-up time for the machine should not exceed four hours. This makes it possible to increase the hatchability of young animals by 2-3% and improve their quality. For this purpose, some specialists equip incubation cabinets with additional heaters. It is also important to place the egg in the incubator already warmed up.

To maintain the set temperature, modern incubators are equipped with automatic adjustment. Failure to comply with the temperature regime negatively affects the development of the embryo and affects the timing of hatching.

In cabinet incubators, the air is constantly mixed by fans, creating the same temperature in its different zones.

Minor deviations over a short period of time have less of an impact, but with high incubation qualities they may not appear at all. If underheating occurs, the hatching time shifts and the results deteriorate. A strong decrease in temperature causes the death of embryos.

Until the 9th day of incubation, underheating is less dangerous, since it only causes a cessation of embryo growth. But already from the 10th day

a prolonged decrease in temperature has a much greater effect than at the beginning of incubation. And by its end it leads to a significant reduction in hatching and low viability of the remaining young.

Overheating of the egg has a greater effect on hatching. In this case, accelerated embryo growth and early hatching occur. Many chicks find it difficult to emerge from the egg. A prolonged increase in temperature to 41-42°C within an hour leads to mass death of embryos.

Even lower temperatures result in low leads and loss of viability. Therefore, despite being equipped with automatic adjustment, the operator is required to check the temperature every hour using a control thermometer.

In case of frequent physiological overheating, cooling is carried out.

Which eggs are suitable for incubation?

Chicks are not born from all eggs. In order not to make a mistake and send a non-viable product for incubation, you need to familiarize yourself with the rules for selecting incubation material.

Round, very elongated, flattened and cone-shaped are not suitable for incubation.

After sorting the eggs by size and shape, you need to check the condition of the shell. It should be even and smooth. Lumps, roughness, cracks, scratches, thinning/thickening, growths, stains and dirt are not acceptable.

If no external defects are found, proceed to check the contents. Ovoscopes are used for this. In the light, you can clearly see the state of the yolk, white, and the location of the air chamber.

Normally, the yolk is located in the center, with a slight shift towards the blunt end. Its consistency is uniform, without inclusions or stains. Color: deep yellow. If an egg in a horizontal position is turned, the yolk will deviate slightly in the direction of rotation (it will not touch the shell) and will return to its original position. The protein should be viscous.

Ovoscopy of eggs The air chamber is located at the blunt end and has clear boundaries. A slight deviation to the side is acceptable. Normal chamber dimensions: diameter - up to 15 mm, thickness - up to 2 mm. When rotating, the camera should not change its position.

Eggs need to be discarded:

  • with two yolks;
  • with mixed white and yolk (uniform in light);
  • with blood clots and blood belt;
  • with dark spots;
  • with yolk stuck to the shell.
  • Poultry farming is a useful and well-paying business. Excellent profits, minimal cash and time costs make it attractive to most small and large farmers. However, despite the apparent simplicity of this enterprise, small pitfalls still exist. Incorrectly selected hatching eggs and failure to comply with storage conditions can negatively affect the entire process. In order for the chicks to hatch strong and healthy in due time, you should carefully examine each specimen that is intended for incubation, and choose exclusively the best representatives. We devoted this article to a greater extent to the topic: storing hatching eggs before placing them in the incubator.

    Storing hatching eggs before placing them in the incubator


    The required humidity in the incubator is achieved through the evaporation of water.

    The optimal relative humidity in it should be maintained within 50-60% in the incubator and 85-90% in the hatcher.

    Turkey eggs require a drier environment during incubation. The required humidity in the incubator is dictated by the level of required evaporation of water from the egg. Constant high air humidity (70-80%) delays the evaporation of moisture, while low humidity (40-50%) stimulates strong evaporation from the egg. It is known that in the initial period of incubation, normal development of the embryo requires increased temperature and humidity in order to prevent stronger evaporation and drying out of the egg. In the second period of incubation, on the contrary, more intense evaporation should be promoted.

    Air humidity in the incubator is controlled using a psychrometer.

    The psychrometer consists of two thermometers on a panel, one of which shows the air temperature in Celsius, and the second has a reservoir wrapped in two layers of gauze, secured with two threads (tightly above the reservoir and loosely below)

    and the resulting wick is lowered into the open neck of the flask with distilled water.

    Water evaporating from the surface of the gauze cools the thermometer reservoir, as a result of which a moistened thermometer shows a lower temperature compared to a dry one. Subsequently, the relative humidity in the incubator is determined using a psychrometric table (see Appendix). At the intersection of the dry and wet thermometer reading lines, the relative humidity is found as a percentage.

    With high humidity during the incubation period, egg shrinkage is too small, and the evaporation of moisture from the egg is limited. This is evidenced by the size of the air chamber, which does not increase at all or almost does not increase, which leads to a difficult conclusion. And hatched chickens remain swollen and are poorly preserved during rearing.

    Violation of the humidity regime in incubation during hatching is easy to establish.

    When the humidity is too high, the bite is noted, but there is no hatching. The beak of the young becomes sticky due to excess moisture, and it dies. When the humidity in the incubator is low, too much water evaporates from the egg, significant shrinkage occurs, and the yolk decreases in volume and becomes denser. The protein becomes more sticky. Before hatching, many embryos have difficulty pecking. And in hatched chicks, fluff sticks together and remains of the shell and subshell membrane stick, usually on the back of the head and back.

    Experienced operators, in addition to psychrometer readings, monitor humidity based on the condition of the air chamber. With normal incubation, by the end of the 18th day the size of the puga reaches approximately 1/3 the size of the egg. If there are deviations in one direction or another, the humidity is adjusted.

    Saving features

    The place where the material will be stored must be well ventilated . Since the shell is very thin and delicate, it absorbs various odors and aromas. You should avoid drafts that affect the evaporation of moisture. After all, it is this that is so important for eggs.

    Can it be stored at room temperature?

    You can store material for producing chicken offspring at room temperature if it does not exceed 12-18 degrees. It is best to place the eggs on a windowsill with an open window.

    If you maintain the required temperature and humidity levels, you can store eggs for 5-7 days. It has been proven that if you hold the material at room temperature for the specified time before incubation, the chicks hatch much better.

    But the storage duration is influenced by the following factors::

    • air temperature and humidity;

    • frequency of sanitary and preventive methods;
    • geographic location of the room in which the eggs will be located;
    • genetic specificity of the laying hen;
    • age of the bird;
    • breed.

    You will find more information about the incubation period of chicken eggs in this article.

    Air exchange (ventilation)

    Air exchange plays an important role in incubation, since the embryo, like a living organism, absorbs oxygen from

    air and releases carbon dioxide and moisture. Moreover, this gas exchange increases significantly towards the end of incubation

    due to the growing demand for oxygen.

    So, if 500 incubated chicken eggs on the 16th day of incubation require only 1.3 m of fresh air per day, then during the hatching period they need 4 m of air per day. If several hundred thousand eggs are placed in the incubator, then it is necessary to provide a ventilation unit to pump in fresh air and remove exhaust air. Subsequently, air exchange in the incubator cabinets passes through ventilation openings equipped with automatic ventilation dampers.

    Intense air exchange is especially necessary in the last days of incubation, when the embryo switches to the pulmonary type of breathing, and insignificant - on its first day.

    Egg cooling

    To remove excess physiological heat, to avoid overheating and to stimulate metabolic processes in the body, eggs require periodic cooling during the incubation period. Cooling is carried out by opening the doors with the electric heaters turned off.

    The duration of cooling depends on the age of the embryo, the air temperature in the room, and the presence of ventilation. The duration of cooling the air in the incubator cabinet to 18-22°C should not exceed 10-15 minutes. It is important that after cooling is completed, the temperature in the cabinet is restored within 20-30 minutes.

    Waterfowl eggs require deeper cooling. To do this, after dry cooling, they are irrigated with water at room temperature from a spray gun.

    How to select eggs for incubation?

    Proper selection of eggs is the main component of the chicken business. For example, chicks will not be able to hatch from substandard samples, so you should always use only fresh options. If they have been left without proper storage for more than 10 days, the possibility of getting healthy chicks is significantly reduced.

    They must be kept at room temperature: keeping them in the refrigerator is contraindicated.

    You should place them with the pointed end up and turn them from side to side periodically throughout the day. Such manipulations will help prevent the yolk from sticking to the edges of the shell.

    Are all eggs suitable for incubation?

    The selection of candidates for future chicks is carried out taking into account shape and weight. Model individuals are those that have just been laid by a healthy domestic hen. If during the inspection specimens were found to be too elongated or perfectly round in shape, or if the shell is rough or contains cracks, they are not suitable for incubation. Two yolks, spotting, other defects that are visible to the naked eye, all these defects make the egg unsuitable for incubation.

    Step 1. The first thing the poultry farmer should do is inspect the eggs, because the productivity of incubation depends on this. A hatchability of 100% can be achieved when several factors coincide:

    • impeccable form;
    • smooth shell;
    • no thickening.

    Step 2. If no obvious damage was found during the initial inspection, you should inspect the egg using an ovoscope - a device to determine its freshness. It allows you to see the location of the air chamber and the yolk.

    Examination of eggs using an ovoscope

    Embryonic development of the embryo

    Unlike mammals, the development of bird embryos occurs in two stages. The first stage is the initial stage, in the mother’s reproductive tract and the second,

    - final, - outside the mother’s body, in the external environment.

    During mating, the male's sperm enter the funnel through the oviduct, where fertilization of the egg occurs. After this, fragmentation of the germinal disc begins. Cleavage grooves form on the yolk (the first - 4-5 hours after ovulation, and the second - 20-25 hours after the first). The grooves are located parallel to the surface of the yolk, forming a blastodisc; its cells, separating from the yolk, form a subembryonic cavity filled with fluid. From the blastoderm cell, the outer germ layer (ectoderm) is first formed, from which the inner germ layer (endoderm) then peels off. The central part of the embryonic egg cell is located in one layer, and there are a large number of them at the edges. Through the central light part of the cell, the dark yolk is visible.

    The germinal disc is in this state at the time the hen lays an egg. The entire process of development of the embryo in the oviduct occurs within 24-27 hours, at a mother’s body temperature of 40.5-41 ° C, under conditions that completely exclude the evaporation of water. When an egg enters the external environment, it begins to cool and water evaporates from it.

    Egg development slows down.

    If the egg is not fertilized, the cleavage process does not occur, and the germinal disc appears as a white flat spot. Further development of the embryo resumes when it enters an external environment favorable for growth: under a hen or in an incubator.

    Under the influence of heat, the embryo continues to develop. During the first 12 hours of incubation between two germ layers

    a third appears - mesoderm. They form the tissues and organs of the bird. The outer leaf is involved in the formation of the nervous system, skin, feathers,

    claws, and the internal one - the lungs, digestive tract, endocrine glands, and liver. From the middle layer will appear cartilage, bones, muscles, reproductive, circulatory and vascular systems. Moreover, the circulatory, nervous, excretory systems, and sensory organs are formed in the first 48 hours of incubation.

    By the end of the first day of incubation, a notochord is formed in the chick embryo

    - temporary spinal ridge of the embryo with the rudiments of the central nervous system. Then, neural folds appear above the notochord along the head process, which eventually turn into the neural tube. Along the notochord (to the right and left of the neural tube), paired segments—somites (primary vertebrae)—appear in the form of square plates. The amnion (one of the membranes of the embryo) begins to form.

    On the second day, vitelline veins, blood vessels, the rudiments of the organs of vision, hearing, some parts of the intestine and allantois appear (another embryonic membrane involved in the respiration of the embryo and serves as a place for accumulation of secretions), the heart of the embryo is formed and begins to contract.

    On the third day, vitelline arteries appear, a complete blood circulation cycle, the rudiments of the liver, endocrine glands, legs and wings are formed, and the amnion folds close.

    On the fourth day, the separation of the embryo from the yolk ends - it turns on its left side, and the intestinal tube is formed. The embryo reaches a size of 0.8 cm.

    On the fifth day, the thymus gland and stomach are formed, and the makings of a skeleton appear. The allantois reaches the boundaries of the air chamber. The length of the embryo exceeds 1 cm.

    On the sixth day, the beak begins to form. Allantois reaches the shell. The circulatory system is included in breathing with absorption

    oxygen from the external environment. The toes and wings are separated. The embryo grows up to 1.5 cm.

    The seventh day is completely spent on sex differentiation.

    From the eighth day, ossification of the skeleton begins, the rudiments of feathers appear, and the kidneys begin to work.

    On the ninth day, keratinization of the beak occurs.

    The eleventh day is a control point in development. The allantois covers the entire contents of the egg and closes at the sharp end. Claws appear. The permanent kidneys are put into operation. The embryo reached 3.6 cm.

    On the twelfth day, the rudiments of feathers appear along the back and tail, the eyelids begin to cover the cornea, forming an oval open hole.

    On the thirteenth day, down covers the entire body, the claws become completely horny by the 15th day.

    On the nineteenth day, the allantois begins to atrophy and the yolk sac begins to retract. Eyes open.

    On the twentieth day, the yolk sac is completely retracted into the abdominal cavity. The umbilical ring closes. Pulmonary breathing and shell pecking begins. When pecked, the chick makes circular movements of its head counterclockwise around the longitudinal axis at the blunt end of the egg.

    Having broken the shell membranes, the chicken tries to straighten up, resting its head and neck on the shell of the blunt end, and its legs on the shell of the sharp end. The shell breaks in two and the chick comes out.

    Peculiarities of embryo development in other species of poultry

    The development of embryonic eggs of other types of poultry follows the same pattern as chicken eggs. The only difference is in the speed of development of individual organs, since the duration of the incubation period is also different.

    For example, a quail egg has an incubation period of 17 days versus 21 days for a chicken egg. The quail embryo develops faster, while the turkey and waterfowl embryo develops more slowly. Therefore, the same growth signs appear in them at different times.

    But the greatest difference in the rate of embryo development, despite the simultaneous start, is noted at the end of the first week of incubation and especially after the closure of the allantois. The closure of the allantois in the embryos of different bird species occurs at the following times: in quail on the 10th, in

    chicken on the 11th day, turkey on the 13th, duck on the 13th, goose on the 14th day. After this, the protein begins to be intensively used by the embryo, after which the allantois disappears: in quail on the 13th, in chicken

    on the 17th, in a turkey on the 21st, in a duck on the 20th, in a goose on the 22nd day of incubation. Thus, the longer the incubation, the longer it takes for the protein to be fully utilized.

    The same thing is observed with the beginning of the retraction of the yolk sac into the body cavity of the embryo. Once the shell begins to hatch, it takes about a day for the yolk sac to retract in quail and chicken, and more than two days in turkey, duck and goose.

    Slow development of the embryo leads to an increase in incubation time: in chicken up to 21 days, in quail - up to 16.5, in turkeys and ducks - up to 27, in geese - up to 30.

    But when analyzing the timing of embryo development, it is necessary to take into account what the storage conditions of the hatching eggs were before laying, and whether the incubation regime was observed.

    Nutrition of the embryo

    Since the development of the embryo occurs outside the development of the mother's body, it is nourished by the contents of the egg - white, yolk and shell. The components of his diet are carbohydrates, proteins, fats and minerals, and their use is uneven.

    In the first week of incubation, the embryo eats mainly carbohydrates.

    As they are used, the supply of carbohydrates is replenished due to the breakdown of fats into glucose. A reserve of carbohydrates (glycogens) is created in the embryo's liver. It is in glycogen that the embryo draws strength to work the muscles and exit the egg. If it is deficient, the embryo is unable to leave its cradle.

    To build the body of the embryo, proteins act as building materials. Already from the third day of incubation, the embryo begins to actively use proteins, primarily egg white.

    Starting from the 6th day, the embryo uses fats in the form of energy nutrition, and from the 16th day, fat becomes the main source of nutrition.

    However, by the end of incubation, not all of the yolk fat reserves are used by the embryo - approximately 30% remains in the residual yolk of the hatched young and serves as its initial source of nutrition.

    To form skeletal bone tissue, minerals from the contents of the egg are used in the first days, and, starting from the 13th day, they are supplied to the embryo from the shell (mainly calcium). Water plays an active role in all metabolic processes during embryonic growth. At the beginning of development, the embryo contains almost 98% water, and by hatching its content is reduced to 80%. And all this water is basically the contents of the egg.

    During the development of the embryo, a constant movement of liquid—water—occurs between it and the external environment. The main part of the water, along with nutrients, enters the embryo’s body through the circulatory system until the 12th day of incubation, and then through the digestive tract.

    Evaporation of water from the egg occurs unevenly and increases towards the end of incubation. In general, water loss is 10-13%.

    Fetal respiration

    It is impossible not to mention the respiration of the embryo, the mechanism of which is not the same throughout development and changes several times: until the third day, the embryo “breathes” the oxygen of the yolk, with the development of the circulatory system

    - with the help of the yolk sac, and already from 5 days of age, breathing occurs through the allantois. On the eve of withdrawal, i.e. On the 19th day of incubation, the embryo switches to pulmonary respiration with atmospheric air, initially contained in the air chamber (exhaust gases are also discharged there). For different gases, the permeability through the shell and subshell membrane is different - hydrogen penetrates the fastest, then carbon dioxide, nitrogen, and oxygen the slowest.

    The level of oxygen consumption and carbon dioxide release depends on the incubation conditions. At high temperatures and low air humidity in the incubator, the breathing of the embryo increases.

    During incubation, a chicken egg releases about 3.5 liters of carbon dioxide and absorbs 4-5 liters of oxygen. Life activity

    the embryo is associated with the formation of heat. Over the entire period, the egg releases 20-23 kcal of heat.

    But until the fourth day, the embryo absorbs more heat than the egg releases. Therefore, at this time the temperature of the egg is lower than in the incubator. Over time, this ratio changes, and by the 11th day the egg temperature reaches the air temperature of the incubator, and in subsequent days it exceeds it by 2-3°C.

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