If you have birds or a reptile as a pet, surely you have learned about all aspects of their care, both general and more specific of his kind. A very important aspect in the life of these animals is reproduction and, as is well known, not all eggs are always fertilized. This will depend mainly on whether or not the male and female have joined, but there may still be other reasons why an egg is not fertilized.
If you are interested in knowing how to recognize a fertile egg, continue reading this article on our site and discover how to do it in a very simple way, with the candling technique.
Before performing the candling test
It is very important to recognize and remove the eggs that are not fertile, because as the days go by they will rot until they burst and contaminate the nest, or the incubator, and the other eggs with bacteria, in addition to producing a very unpleasant odor. To do this, first, we must make sure if there is a male living with the female and if they have easy access to each other. If so, it is possible that the eggs that the female lays are fertile, although not all of them may be.
Before doing the test we must wait a few days until the eggs have incubated a bit. For example, in the case of chickens, you have to wait about seven days. If we do the test before having left a few days of incubation, we will not be able to know the result with certainty. If we observe that the female does not incubate the eggs, we can already rule them out, since it is most likely that they are not fertile and if they are, if they are not incubated from the beginning, they will not succeed.
It is really vital for the development of the embryos Do not do the test every day, or very often We must do it at the beginning (between four and seven days in the case of hens), and after a week (in the case of hens on day 14 would be adequate) we will carry out the test once more, in case we want to be more sure and check the development of the embryos. After this last review we should not move the eggs anymore, as it is very important that the days before the egg hatches it does not move or change temperature. Therefore, we do not need to do it more times. If we were doing it more constantly, we would cause development problems, because we would be changing the temperature of the egg too many times and it would be damaged and even stop developing.
Finally, before carrying out the test against the light, we must gather the necessary material We can do the test with a simple flashlight, we can build a homemade candling out of a box and a light bulb or flashlight, or we can buy a candling machine, which is simply a machine with a powerful and highly focused light shaped for use on eggs. The flashlight must be the same diameter or smaller than the eggs, if it is larger we will have difficulties to do the test correctly. Once we have the flashlight or the candling scope, we can start the test to see if the eggs are fertile or not.
How to candle test to check the fertility of an egg
The candling test involves illuminating the egg with a strong light so that all the light passes through it, thus being able to see what is inside the shell and to check its condition. To carry out the candling test and find out the fertility of the eggs, we must be able to be in a completely dark To do this we must turn off all the lights and even make sure that no light enters through the windows.
If we use an ovoscope we will only have to place it properly on the surface of the egg. But if we do it with a flashlight, as it does not have a suitable shape for the surface of the egg, we must circle the flashlight and the egg with our fingers avoiding the light escapes between our fingers and focuses all through the egg. In the case of bird eggs we can focus the light from the point we want on the egg. We can turn it to find the angle that best illuminates its interior.
When we have properly lit the egg we will be able to observe many things: if it is fertile or not, if it has cracks that put the development of the embryo at risk, etc. To know if it is a fertile egg or not, we must pay attention to whether we can see a dark point from which small spider-like veins emerge, that is the center of the embryo and developing blood vessels. This tells us that the egg is actually fertilized and an embryo is developing inside the shell. If we do not see it very clearly, we can let the egg continue to incubate and wait for the next test after a week to finish confirming or ruling out fertility.
Other signs that we can appreciate will be the absence of stains and blood vessels, therefore it looks uniform, in this casethe egg is infertile If it is the first test we have done on an egg that looks like this, we can still leave it and wait for the next one to check that there has been no development late.
In the second test that we carry out we will be able to observe that perhaps some egg that was developing the first time we examined it has stopped doing so. This is due to various reasons, such as genetic problems, temperature changes, inadequate humidity or infection by bacteria that have been able to access the interior of the egg through cracks. For this reason, in the first test that we carry out we must write down if we see any crack in the egg shell, no matter how small.
It is possible that in this second recognition we will see that a blood ring has appeared, which we will observe as a well-marked red circle. This is a very reliable indicator that the egg has stopped developing. Another way to indicate that the embryo is no longer developing is to visualize various bloodstains, although sometimes it is difficult to differentiate it from an embryo in its early stages, so in this case we can let it continue to incubate.
It will be good if we list the eggs and take notes of what we have seen in each one, to be able to compare the results in the next test that we do and thus be able to check their development. We can keep the eggs out of the nest or the incubator for a maximum of 20 or 30 minutes to be sure that the development of the embryos has not been affected. Birds often leave the nest for a few minutes, but we must be very careful not to overdo it to prevent them from incubating them.
Differences in the case of reptile eggs
The gestation period of reptiles is generally longer than that of birds. Therefore, to perform the first test we must wait between 15 and 21 days.
Another very important difference is that reptiles are much more sensitive to temperature during incubation Therefore, we must be very careful time and ensure that the environment of the test site is of a temperature similar to what they may have in the nest or incubator. It is possible that depending on the size of the nest and the number of eggs there are, the temperature may vary a few degrees from one part to another and for this reason the eggs will have different temperatures, for example, if they are more on the surface or on the bottom. In addition, this small difference in temperature is one of the factors that determines the sex of the embryo.
It is vital for the development of a reptile embryo that the egg is always in the same position Therefore, when you Whenever we drive, we should try to keep it in the same direction that we found it, vertical or horizontal, and never turn it around. To be sure we can make a mark on the surface of the egg that is facing up, with a special marker or marker. Therefore, we will do the candling test with the egg in that position and return it to the exact same place in the nest or incubator and in the same position. If we don't do it this way and turn the egg over, the embryo can suffer various damages and even die, so it's really worth taking our time and doing it slowly and well.
