Let's take a look at some of the tougher questions.
The most difficult question we sometimes get is this: Why didn't my eggs hatch?
The main reason why this is such a difficult question to answer is because there are many factors that affect the results of your incubation efforts. Some of these factors are: egg quality, fertilization, improper temperature levels or humidity levels, dirty or contaminated eggs, mis-handled eggs, temperature spikes or valleys, too much temperature variation, poor egg turning, eggs are too old, or not enough fresh air. Let's look at each one and see what we can learn.
- Egg quality: The hen's health can have a big impact on this. Ensure the hens are healthy and strong. This increases the likleyhood that the eggs will be strong. But even with a strong hen, some eggs just aren't strong and healthy enough to grow into a healthy chick.
- Fertilization: If your flock has a strong, mature male, they normally do a pretty good job doing what they are suppose to do. There is a reason why they call it "the birds and the bees." But even with the male's best efforts, not every egg gets fertilized. That is why candling your eggs after the first week is a good idea so you can remove those that are not developing.
- Improper temperature levels or humidity levels: These next few items are related but a bit different. Improper temperature level could mean the temperature is too high or too low. Neither one is good for your eggs. But if you have to choose, being a little low is better than being a little high. If you are a degree or two too high, your eggs will hatch early, often with a reduced hatch-rate and sometimes with physical deformities. One common deformity is an extra toe or two. If you are a degree or two too low, your eggs will hatch late and with a reduced hatch rate. No matter what your thermometer tells you, if your eggs hatch early or late, adjust your thermostat settings accordingly.
- Temperature spikes or valleys: This has to do with occasional drastic changes in temperature. If there is a one time temperature spike, let's say it goes up to about 104 or 105 and it is only there for a few minutes, then your eggs will probably be just fine. See the section below regarding the temperature change inside the egg itself. If the temperature stays there for an extended period of time, then it will likely kill the eggs. The same is true for temperature drops. This is most common where there is a power outage for a time.
- Too much temperature variation: Some variation in your incubator is very normal and acceptable. The problem comes when the variation is too large. Please see the next section (our 2nd most difficult question) below for details regarding this issue.
- Dirty or contaminated eggs: There are two problems with dirty eggs. First, the dirt or muck on the egg keeps oxygen from entering the egg and carbon dioxide from leaving the eggs. Just like the placenta in a mother's womb allows for the exchange of these two gases, the chick's shell does the same thing. If it is too dirty, the exchange can not happen and the developing embryo will suffocate and die. The second issue is that it could introduce bacteria into the incubator which can permeate through the shell and grow in the protein-rich environment inside the shell. And thus kill the growing embryo. Make sure your eggs are clean, but do not wash with water, use a dry towel or rag. A wet towel can remove the protective coating on the egg which helps keep out harmful bacteria.
- Mis-handled eggs: This is particularly a risk with mail-order eggs. Sometimes the post office is gentle and nice. Sometimes they are not. It's risky, but that doesn't mean you can't be successful with mail-order eggs. You just have to assume your hatch rate is going to be lower. And sometimes you'll be pleasantly surprised.
- Poor egg turning: In nature, a mother bird will turn her eggs many times a day. As you incubate eggs, you must replicate this by either using an automatic egg turner or by turning the eggs by hand. It's important to ensure your hands are clean to avoid getting dirt or oils on the shell which can inhibit the exchange of essential gases (see "Dirty or contaminated eggs" above). If an egg is not turned enough, the yolk may stick to the shell which will cause the embryo to die. One common symptom of this is the insides of the chick developing on the outside of the bird. It's not pretty and quite sad to see. An egg needs to be turned multiple times a day. At least three times and many people suggest turning 5-7 times per day. An auto turner will normally turn (or rock) the eggs 6 times per day.
- Eggs are too old: Most people agree that the maximum amount of time to store eggs before starting to incubate them is about 7 days. After that the hatchability begins to decline dramatically. Eggs should be kept cool and safe. Also, they need to be turned during storage, but not as often as during incubation. Once or twice a day is all they need.
- Not enough fresh air: As described in the "Dirty or contaminated eggs" section, eggs need oxygen to grow and develop. If all of the vent holes in the incubator are closed and there is no circulating fan, the eggs may not get the fresh air they need. Be sure to follow the manufacturer's instructions regarding how to use the vent holes in your incubator.
The next difficult question is: Why isn't my incubator stabilizing at the correct temperature?
Most often we find that this question is asked because the person isn't familiar with what a realistic and acceptable temperature range is. Many people assume that since the ideal temperature is 99.5 degrees F that the temperature must stay at that exact point the entire time. The reality is that there is an acceptable range in which the eggs will hatch just fine. Please keep in mindy that the air temperature in your incubator will change much faster than the temperature inside the eggs. This means, for example, that if the temperature is rising to 101 F and then falling to 98 degrees and the cycle continues every few minutes, that fluctuation is just the temperature of the air in the incubator. Since the eggs warm and cool much slower than the air, the actual variation the eggs are feeling is much, much less than that. It may be absolutely negligible. That is one reason why the egg-o-meter is so popular: it gives a more accurate gauge of the temperature that the INSIDE of the egg is experiencing.
But for those who are seeing variation that is not just the normal variation in an incubator, your question is a little trickier to answer. And just like the question at the top of this page, it's a little more difficult to answer because there are many possible reasons for it. More coming soon....