The Chook Shed - Breeding chooks: Incubation

Incubation - Artificial and natural

Most serious breeders of show fowls use incubators to hatch their chicks. This is because broody hens are often unavailable when the supply of hatching eggs is greatest. But broodies still give excellent results when available.

Firstly we will look at artificial incubators. There are two different kinds of incubators, still air and forced air and there are three basic physical principles for incubation (which are the same for both types of incubator), however the methods used are different for each.

Temperature
Development of the embryo can only take place at the correct temperature. Too cool and the chicks hatch late and are generally soft and weak. Too hot and the chicks hatch early, may be deformed, have bloody navels which refuse to heal and are generally weak. The correct temperature varies depending on the type of machine is being used.

Humidity
Without adequate humidity, the egg loses too much moisture; too much humidity the egg loses too little moisture. Again, this is variable between the two kinds of incubators, due to air flow and ventilation methods.

Egg turning
For many years it was believed that the hen turned the egg to prevent the embryo sticking to the shell membranes. While this is certainly one reason for turning the eggs, the main reasons are to float the embryo to fresh food within the egg and to move it away from its own wastes. To give the embryo the best chance, turning should take place at least three times each day and optimally more often. Eggs which are collected from breeding birds which have not been fed a high protein diet must be turned more often than those from well-fed stock.

The still air type incubator is the trickier of the two to set up correctly. An incubator works best in a room with a steady air temperature of around 68-70 degrees Farenheit. The incubator must be set exactly level or temperature variations will occur inside the egg chamber. The temperature is set to 103 degrees Farenheit, which is very close to that which is found under a broody hen. The temperature in this type of incubator is measured at the top of the egg. Unfortunately, this means that eggs of different sizes cannot be successfully incubated together in a still air machine. Wet bulb thermometers do not prove successful in still air incubators, so humidity must be measured by regularly checking the air cell inside the eggs. Eggs which have air cells which grow too large indicate humidity settings which are too low. When turning eggs in a still air incubator, it is best to have an external turning mechanism. This means the egg chamber does not have to be disturbed too often, lessening the occurrences of excessive temperature fluctuations.

The forced air incubator uses a fan mechanism to move the warm air around the egg chamber. This means a wider range of egg sizes can be incubated together as the ambient air temperature is more evenly dispersed within the incubator. This incubator is usually set at 99 to 100 degrees Farenheit. Humidity setting can be accurately measured with a wet bulb thermometer with usual settings of 82 to 88 degrees Farenheit for setting and 94 degrees Farenheit and over for hatching. Egg turning is usually facilitated from outside the egg chamber by a mechanical device. With both kinds of incubators, it is important to stop egg turning three days before the hatching date.

No matter which type of incubator you opt for, keep a notebook detailing any problems and successes which are encountered. The next page details incubator problems and how to fix them.

Using the old-fashioned (but still ever reliable) hen
Contrary to some beliefs, hens are still the most reliable method of incubation. After all, they have perfected the technique over thousands of years and they can do it without you having to do anything. Hatching percentages are usually much better with naturally incubated eggs than those that are artificially incubated.

When planning to set a hen, do not be tempted to leave the eggs in the nest until she goes broody. Remove the eggs daily and replace each with a plastic nest egg (even white golf balls will do). This ensures the eggs are fresh and protected until she is ready to go broody. The previous page deals with egg collection and storage.

You can tell when the hen goes broody. She will not leave the nest at all and will fluff herself up if disturbed. She may also make a strange squawking noise and peck at your hand. When you notice such behaviour, leave her sitting on the plastic eggs or golf balls for about three days before replacing them with eggs. This is to make sure she is actually broody as some hens will leave after a few days, thus spoiling any eggs she may have had. During this time, gently take her from the nest and replace the nest litter with clean, dry pine needles. Give the nest and the hen a liberal dusting with a sulphur-based insect powder. You can also place pieces of Wormwood in the nest as a deterrent for insect pests. When you are finished and sure she will sit tight, wait until night time and replace the fake eggs with the real ones. She will be quieter at night and less likely to peck you or fly off the nest.

If you have other hens in the same pen, you should either remove them to a different shed or wire off the nest box with the broody hen otherwise you will find they will lay all their eggs in the box with the broody. When this happens it is unlikely you will have a successful hatch.

Some hens will not leave the nest for any reason over the three week incubation period and it is important to make sure she gets off now and then (at least once every three days) to eat, drink and defecate. Just lift her gently out of the box (ignoring the pecking beak) and you will find she will go about her business once off the nest. Do not be afraid of the eggs chilling, she will not stay off too long. Just be sure that any eggs are not caught in her feathers when you lift her out or they may drop out and break. Each time she is off the nest, give a light dusting of the box with sulphur-based insecticide powder to keep any nasties away.

The eggs will usually hatch after 21 days so at about that time, make sure you have everything ready for the new-born chicks and the mother. Make sure the hen AND chicks can get in and out of the nestbox. Many chicks die when the hen leaves the box and the chicks cannot climb out (and vice versa). Finally, do not leave other adult birds in the pen with the new mother as quite often they will kill the chicks or at the very least bother the hen so she cannot give all her attention to her brood.