Egg Fertility Basics
Most people don’t realise that you need fertile eggs to hatch a chick.
Eggs are laid by female chickens. You need a rooster (male chicken) with your hens to be able to hatch your own eggs. And to ensure you have a high fertility rate, it is best to have one rooster for every 3-8 hens. The best ratio I have found is having 2 roosters covering ten to twelve hens.
Diet is also important. You need to ensure that your flock has a well balanced diet and has plenty of water. Any stress to your chickens will result in poor quality eggs and low fertility rates. Regular layer pellets provide a good balanced diet. But chickens LOVE scraps and fresh leaves. So anything from your table that you don’t eat (this includes small cuts of meat too) are perfect for chickens. Any weeds you pull from your garden are also excellent supplements for your flock, especially all the slugs and snails!
Chickens do not lay eggs all year round. They have a “break” over the winter months and stop laying daily. When daylight hours start to lengthen (after June 22nd in the Southern Hemisphere), chickens begin to lay more eggs again. The last month of winter is considered by most to be the start of the breeding season for chickens. The eggs laid during the last month of Winter and through Spring are the best used for hatching.
Here is an image of some of our Plymouth Rock flock chowing down on some scattered feed and fresh leaves.
A fertile egg is one that has a sperm bundle with it. If you grow your own chickens and use their eggs, you will notice this as an extra yellowish bundle attached to the egg yolk when it is cracked open.
You cannot check for fertility immediately after laying. This is especially true for eggs that have a thick shell or dark colour. The best time to check for fertility is around 5 days after incubating starts. This is done using a technique called candling. Essentially, you shine a bright light through an egg to determine if the embryo has started to develop. A developing embryo is one where you can clearly identify blood vessels traversing through the egg white from the embryo (egg yolk). Any egg that is not fertile needs to be discarded. Nothing smells worse than a rotten egg exploding in an incubator. Blech!
Collecting eggs for incubation
Eggs that you collect for incubating need to be treated a little differently to those you use in the kitchen. Here is a list of pointers…
Do not wash your eggs
A chicken has only one “out hole” … for everything! (Yes, this means that every egg laid comes out of the same place where its’ excrement come from.) This is why eggs used in the kitchen need to be washed to ensure that pests and diseases are not transferred to us. But when you are collecting eggs for incubation, do not wash them. If the eggs are particularly dirty, you can scrape it off or quickly wash it under running water.
There is a thin membrane on the outside of every egg which protects the contents of an egg from pathogens. Washing your egg will break and/or remove this membrane, leading to a greater potential of infection to a developing chick.
Use your cleanest eggs
Egg shells are porous. It is through the small holes in the shell that a developing chick will breath. You get a better hatching rate from clean eggs than from dirty eggs as they are exposed to fewer potential pathogens.
Turn your eggs at least once per day (twice is better)
Store the eggs you collect in an egg carton and mark them with a pencil or thin marker (so no one will eat them!). At least once per day, rotate the egg carton. I find it easiest to remember doing this at breakfast and at dinner.
Rotating your eggs daily ensures that the egg yolk does not stick to the inside of the egg shell. This causes deformity as the chick developed if it occurs.
Use your freshest eggs (unto 7 days old is best. Up to 10 days old can still work)
The freshest eggs develop the best. This is because the embryo deteriorates over time. From 1-7 days, the embryo is at its optimum performance. Between days 7-10, the membrane around the yolk starts to break down. An egg will not start to develop until you start to incubate it.
When you collect your eggs, write the date on them. Just the day is fine (e.g. 22/09/2014 only needs “22” written on it). That way, you will always know how fresh your eggs are.
Keep them at room temperature
To ensure that an embryo does not die before you start to incubate it, keep it at room temperature. You can refrigerate them, but as most fridges internal temperatures vary and a lot of modern fridges are “frost free”, it will kill the embryo before incubation. An egg shell is porous, so fluid will slowly evaporate through the shell quicker in a “frost free” fridge than at room temperature.
Check out our other post about incubation for more info on hatching your own chicks.