Incubating Eggs and Hatching Chicks
I find hatching chicks to be one of the more rewarding aspects of being a chicken fanatic. Not only is the hatching process itself fascinating, but also there is tremendous satisfaction to be had in breeding and improving your own line of birds. There are two way to hatch chicks:
1) naturally with a hen
2) artificially with an incubator.
Both methods naturally require a supply of clean, fertile eggs.
The egg is naturally equipped with barriers against invasion by harmful bacteria, and can be hatched without any treatment. Rubbing can remove most loose dirt, but remember that the egg has a transparent, protective barrier (the cuticle) which may be damaged by excessive handling. If there is so much dirt on an egg that it needs to be washed, always use water that is warmer than the egg. Hatcheries often use antibiotic dips and fumigators for their eggs, but this should not normally be much of a concern to the small breeder.
For most small breeders, natural hatching is the easier and most convenient method. The fact that much space on this page is devoted to incubation is an indication of the relative difficulty of this method rather than an endorsement of it. With natural hatching, one need only provide hens, a rooster and nest boxes, and in twenty-one days chicks should begin hatching. Of course, if your hens are setting, they won't be laying. This can be a problem if you are interested in maximizing your production of eggs and/or chicks. Another hitch is that most common breeds will not set on their eggs; Their parental instinct has been bred out of them. My solution to hatching these non-setting breeds is to keep several hens in my flock from "broody" breeds, such as cochins, silkies or game fowls. Hens from these broody breeds will readily adopt and hatch the eggs of non-setting hens.
Remember that, although hens will lay eggs without a rooster, these eggs will not be fertile and, therefore, will never hatch. So keep the rooster around, even if he crows too much. The ideal ratio of hens to roosters can vary widely between breeds and program goals, but a ratio of ten hens to one rooster is a good rule of thumb for the average flock.
Development in the Egg
Growth begins in the small fertilized area at the top of the yolk. A network of blood vessels begins to develop, spreading from the embryo out over the yolk. The yolk sac is attached to the chick's gut via the navel. Out of the navel, another membrane also grows that is similar to the placenta of mammals. It is called the chorio-allantois, and it grows along the inside of the shell, eventually covering the entire inner shell membrane. Its plentiful supply of blood vessels enables it to carry oxygen to the embryo and to eliminate carbon dioxide through the shell pores. It also carries nutrients to the developing embryo via the blood supply, through the uptake of albumen and calcium from the shell. Finally it stores the chick's waste products. In the last few days before the chick hatches, the chick draws blood out of the chorio-allantois, and its abdomen closes around the yolk sac.
Stages in the Development of the Chick Inside the Egg
A freshly laid fertilized egg has a blastodisc on the side of the yolk. As the embryo grows, blood vessels grow over the yolk sac and the chorio-allantois grows onto the sides of the eggs. The enlarging air space at the large end of the egg will cause it to tilt slightly when laid on a flat surface.
Just prior to internal pipping, the inner membrane dries and lies down over the chick. The yet larger air space causes a very noticeable tilt to the egg. Just before pipping the shell, the chick will occupy the entire space of the egg. The yolk sac is drawn in through the navel. At this point, the egg will not tilt on a flat surface. Some chicks will hatch out completely within a few hours after pipping, others may take as long as a day. Either is normal and no intervention is necessary unless the chick becomes disoriented and slips its beak back down into the egg. On the rare occasion that this happens it may become necessary to remove a few pieces of shell so that the chick does not suffocate.
An incubator is basically a machine which hatches eggs through applying artificial heat to them. They come in all shapes and sizes, designed to suit a variety of production goals. Incubating allows one to hatch eggs under controlled conditions, which may be advantageous in terms of such concerns as disease control. However, I use an incubator because it simply allows me to hatch more eggs than is possible through natural incubation alone. Further, if all of one's hens are of a non-setting breed, then it becomes absolutely necessary to use an incubator to in order to hatch one's own eggs. There are four principal factors to consider in the incubation of eggs: temperature, humidity, air circulation and turning.
Temperature control is the single most important factor in the successful incubation of eggs. Most upscale incubators have self-regulating thermometers, and are, therefore, easy to operate. However, most inexpensive incubators (like what I have) have manual thermostats, which makes it difficult to maintain a steady temperature inside the incubator when the external temperature is unstable. Placing the incubator in a climate controlled room helps mitigate this problem, but be careful not to inhibit air circulation. And never trust your thermometer; Most of the ones that come with incubators are cheap and inaccurate. Buy a quality thermometer and regularly check it against a second one.
In most incubators humidity is usually regulated simply by placing water in trays or channels inside the case. Some incubators have sophisticated sensors that allow for exact regulation. Humidity levels can be raised by limiting the air flow through the incubator, but this is not recommended as it will interfere with the supply of oxygen to the eggs.
Turning the eggs is necessary regardless of what type of incubator is used. Hens turn their eggs frequently by shuffling them from side to side, which keeps the embryo from settling on one side of the egg. Most incubators have automatic turning devices that turn the eggs every few hours, but it is possible to turn eggs by hand if it is done at least twice a day. When using an automatic turner, always place the eggs with the pointed end down and the rounded end up. If a turner is used, eggs must be removed from the turned about week before hatching and placed either on a flat surface in the incubator or in a separate hatcher.
Air circulation is important because the eggs need a steady supply of oxygen from outside the incubator through external vents. Further, air circulation inside the incubator helps to maintain an even temperature. Most sophisticated incubators will have an internal fan which constantly circulates the air. Such forced-air incubators are especially necessary for incubators with several trays stacked over one another, because hot air naturally rises. I use a single level, still-air (fanless) incubator and have only had circulation problems when I severely overloaded the incubator and, thereby, restricted air flow.
Common Incubation Problems
While there are a myriad of factors that may complicate the hatching process, by and large the most common problem is temperature control. More expensive incubators have self-regulating thermometers, and are, therefore, easy to operate. However, most inexpensive incubators (like what I have) have manual thermostats, which makes it difficult to maintain a steady temperature inside the incubator when the external temperature is unstable. Placing the incubator in a climate controlled room help mitigate this problem, but be careful not to inhibit air circulation. Never trust your thermometer; Most of the ones that come with incubators are cheap and inaccurate. Buy a quality thermometer and regularly check it against a second one. Most incubator manufacturers will tell you to maintain a temperature of about 97 degrees Fahrenheit for chicken eggs. However, you will virtually always have to experiment with your temperature settings. When conditions are ideal, chicks will hatch like clockwork at 21 days. It is important to mark your eggs with the date they were laid so that you know exactly how long it is taking for them to hatch. I use pencil for fear of toxins in inks.
Early hatches indicate the incubator temperature is set too high. Often chicks hatched early will have a bloody membrane (chorio-allantois) inside the shell, and the yolk sac may not be fully absorbed into the abdomen. It is normal for shell membrane to be attached to the chick’s navel when it hatches, but this should quickly dry out and fall away . Late hatches indicate that the incubator temperature is set too low. Often late chicks will not make it out of the shell or, if they do, are weak and unthrifty. They are generally underdeveloped, often having malformed feet and partially absorbed yolk sacs. The overall window for hatching is from 19 to 23 days. Very rarely will a chick hatch much less survive outside of this window.
When making temperature adjustments, don't over react. Remember, you won't know the results of your actions for three weeks. I have had luck adjusting the temperature one degree up or down for each day above or below the 21 day mark. If your eggs never hatch, open them up to determine the stage of development when things went wrong. There will always be some problems unrelated directly to incubation, such as infertility and chicks malpositioning in the shell.
A brooder is nothing more than an enclosed area with a heat source. Ideally, the temperature around your heat source will be about 95 degrees Fahrenheit. But always give chicks enough space in the brooder so that they can move freely to and from the heat source. This way they can regulate their own temperature. I use a two inch layer of coastal hay as litter in the bottom of the brooder. This provides good insulation for the chicks and is very absorbent.
I keep two brooders. The first is nothing more than a cardboard box with a 60 watt light bulb mounted in a clamp light in one corner. I usually keep chicks in this box for three days, as a postnatal recovery area. Don't be frightened if your chicks sleep like the dead and don't eat or drink right away. This is normal, and the yolk sac can sustain a chick for several days. After about three days, chicks normally start to become more active and demand more food and water. At this point I remove them to a second brooder, which is a larger, metal model with feed and water trays mounted on the sides. It has a tight screen mesh floor. Chicks may stay in this brooder for over a month. As it is rather warm in Texas, I can usually move the chicks into unheated pens when they are about five week of age. In my opinion, there is no point in spending a lot of money on a brooder, unless you are really serious about some major production. Even then, you should not have to spend a fortune. I have seen hatcheries operate quite successfully using nothing more than wire pens with heat lamps. The purpose of brooders is merely to keep the chicks warm until they are old enough to handle normal outdoor temperatures.