Candling is a process of being able to see the insides of an egg without having to break the eggshell. Candling is a useful process in that it allow individuals to identify whether or not the eggs are fertile or infertile. Identifying infertile eggs early in the incubation process allows those infertile eggs to be removed from the incubator altogether; preventing bacteria from growing within those eggs.
Furthermore, if the infertile eggs do begin to contain bacteria, that bacteria can spreads to the fertile eggs and reduce the number of fertilized eggs that will successfully hatch. To candle eggs, individuals must hold the eggs up against a bright light in a darkened room. The shells of the eggs are semi-transparently to the light, allowing for the contents of the egg to be visible.
How to Candle Eggs and Find Fertile or Bad Eggs
Within the eggs is an air cell that can be visible to the individual that is candling the eggs. The size of the air cell can reveal to the candler the humidity level of the incubator. Should the air cell be too small, the humidity within the incubator is too high which could drown the embryo developing within the egg.
Too large a air cell indicates that the humidity within the incubator is too low which could lead to the embryo dehydration. Fertile and infertile eggs often appear the same when first candled. However, after allowing the eggs to incubate for several day, the fertile eggs will begin to show signs of development within the egg.
Fertile eggs will contain red veins within the egg which are the embryo’s “heartbeat” network, as well as a dark central dot that is the embryo itself. Infertile eggs will be clear within the egg as they do not contain an embryo. Around day seven of incubation, perform a major candling check to differentiate between fertile and infertile eggs.
Any clear egg should be removed from the incubator at this stage as the eggs will rot within the incubator if left to sit. Within the egg may be seen a blood ring which is an indication that the embryo within the egg has died. Blood rings are caused by genetic and temperature-related issues within the embryo that result in halted development.
Blood rings can be seen between days three and seven of incubation. It is important that individuals not shake the eggs to try to locate blood rings as this can lead to the eggs being ruptured and the spread of bacteria. Should an egg contain a blood ring or be rotten, the person should remove that egg from the incubator altogether.
Rotten eggs will contain a cloudy and/or brown interior to the egg and will emit the smell of hydrogen sulfide. To candling the eggs, individuals should follow a specific schedule. During the candling process, eggs should never be removed from the incubator for longer than fifteen minutes.
Fifteen minutes is the maximum amount of time that the egg should be removed from the incubator as leaving the eggs in such a state for longer periods can lead to chilling the embryos within the eggs. The first candling inspection should be performed on day seven to inspect for any clear eggs and blood rings. A second inspection can occur on day fourteen to inspect for any eggs that may have ceased to develop the embryo within the egg.
The final candling inspection should occur on day eighteen prior to the lockdown period. On day eighteen the person should stop the eggs from being turned and the person should increase the humidity within the incubator to assist in the “pip”ing of the eggs; the “pip”ing is the process of the embryo within the egg creating an opening to expel the waste of the embryo. Any egg that does not pip by day twenty-three is likely dead.
Infertility typically begins in the coop where the eggs are produced. Should a rooster struggle to successfully fertilize the eggs, there may be an issue with the rooster itself. For instance, the rooster may be too old to successfully fertilize the eggs, or the rooster may be experiencing heat stress.
A ratio of one rooster to ten hen should be maintained within the coop. Furthermore, the hens should be fed a balanced diet to ensure that their fertility. If the hens are too obese, there fertility may be compromised.
An LED candler should be used during the candling process. LED candlers are more effective than a phone flashlight in that the LED light is more powerful and can penetrate the dark colored shells of the eggs. During the candling process with the LED light, individuals should inspect the eggs for the presence of veins, movement within the egg, and the size of the air cell.
By inspecting for these three elements, individuals will have the information necessary to decide which eggs to keep in the incubator and which to remove.