Fertile Eggs - Chicken Egg Hatchability Problems
There are a number of problems that can arise for the hatch ability of eggs. They are generally in the following categories:
- problems within hatchery or property of parent birds
- handling of the eggs
- breeder flock
identifying these problems is essential to ensure a more successful outcome in future and requires all information from the above categories to determine the issue at hand. Detailed records are essential - every piece of information that can be obtained will help you locate and resolve any hatching issues.
The biggest issue I find is people attempting to hatch eggs in incompetent incubators but expecting brilliant results. Generally these cheaper incubators are not only a fire risk at times, but they generally put people off from hatching - they do not stay true to temperature and humidity becomes a nightmare to control.
The other common misunderstanding with new chicken lovers trying their hand at breeding is that not all eggs will become viable and hatch! many people expect 100% results 100% of the time. Rare breeds in particular are rare for a reason and sometimes it is due to small gene pools, or dark pigmented eggs that create hatching problems, and people expecting perfect results that come easy. Marans for example have a dark pigmented egg, and can quite often take up to day 24 to hatch. The dark pigment is almost like another layer for a chick to pip from. Hatchers opening incubators and letting humidity escape prevents further chicks from pipping, making shells hard again and trapping chicks in the shell, then dying.
I have compiled a list of other issues and how to identify some of the reasoning behind the problem:
PROBLEM: Infertile eggs with no blood and a small white germinal disc that, when candled, shows clear
CAUSES: There are a number of things that can cause this problem, many of which can be easily solved and some of which is beyond our control. Some examples include: extreme weather conditions, inadequate lighting (so dark winter months can factor - hence why we do not realise fertile eggs until winter is well and truly passed) and inadequate floor space per bird. You should also inspect the breeder flock for parasites, feet and leg problems, excess body weight (yes! overweight birds will not be mating) or breeder flock that is too young or too old. Exposure to drugs, pesticides, toxins and mycotoxins can also cause an issue with fertility. It has also been indicated that Ivomectin use on poultry can cause infertility. Infertility can also be caused by disease in parent birds. Signs of this may include rough, mishappen or thin shelled eggs. Infertility can also be cause through rough handling or shipped eggs that have been damaged in transit.
PROBLEM: Fertile eggs that have no blood, have a germinal disc which appears enlarged, and which candle clear may be referred to as "blastoderm without embryo"
CAUSES: This is another issue than can stem from breeder stock that are too young or too old, a disease in the flock or exposure to drugs, pesticides, etc. However, many other causes of this problem are related to handling. These can be due to the eggs being stored too long, being held under improper conditions, washing the eggs at too high a temperature, fumigating incorrectly, being jarred or exposed to sudden sharp changes in temperature in transport.
PROBLEM: eggs that, when candled, show clear, containing a blood ring or an embryo which has died within three days of incubation
CAUSES: This issue has many of the same causes as the previous issue. However, other causes may include inbreeding and nutrient deficiencies
PROBLEM: Embryo that have died within three to six days of incubation, an embryo on its left side with a yolk sac circulatory system and no egg tooth
CAUSES: Sharing many causes with the blastoderm without embryo, this problem has the addition potential causes of a lack of proper ventilation, inproper turning of the eggs in incubation, or vitamin deficiencies.
PROBLEM: Embryo that have died with seven to seventeen days of incubation, each with an egg tooth, feathers/feather follicles and toenails
CAUSES: With this issue, it is important to check incubator conditions. There may be a problem with temperature, humidity, turning, and/or ventilation. This problem can also be a sign of contamination, nutrient deficiencies, or lethal genes.
PROBLEM: Embryos have died past eighteen days of incubation
CAUSES: Incubator conditions can again be an issue, as can contamination, particularly from moulds, improper fumigation techniques, transfer temperatures, handling of hatcher can also be a factor. There could be a issue with shell quality or broken shell.
It is very important to candle eggs and remove any unviable eggs from the incubation process. At lock down (day 19) all unviable and dead in shell should be removed. These dead embryo can contaminate any remaining viable eggs in your incubator, either by bacteria seepage from the shells or explosion of eggs.
Read more on this topic here: Eggtopsy