Stop developing after ~17/18 days, could season be a problem?

I'm a back yard breeder, mostly for fun with my young girls and to sell locally. I have been breeding for the last two years. RIR roo to RIR hens, barred rock hens, easter egger hens, and black star hens. In past two years, I have only bred in early spring through late summer and typically get between 85%-90% hatch rate. This late summer I switched to an amauracana roo. The last 3 attempts at hatching I'm 5/42 all three times. I've candled and everything looks fine up to 17/18 days but then they don't hatch. I've opened up dead eggs and everything appears to be fine with respect to development up to where they just seem to stop. I monitor temp very closely, I don't monitor humidity at all. When there is no more water, I add some to the pan. During the summer it is really humid and I only refil water once over the 3 week period. Now with it being more dry, every 3 days. I know people will want to say that my problem is my not paying attention to humidity, and that may be right, but keep in mind I have 20+ hatchlings under my belt with between 85%-90% hatch rate using my "method". The only changes is a new roo and change in temp. I don't understand why everything is fine up to 17/18 days and then almost everything dies at that point. Any thoughts or suggestions are most welcome.

Sorry your hatches have been off. Are you monitoring your air cells? Have you done eggtopsies on the DIS chicks? What did you find? Lots of liquid? Did they internally pip? Were they dry? Did your chick development at presumed day of death match the charts in "hatching eggs 101"? If you're not monitoring your humidity, that could be the difference. Much change in ambient humidity in most areas between spring/early summer, and late summer/fall. What are you using for thermometer? Digital or bulb? If digital, the accuracy could change over time. I would expect bulb to be more consistent. What are you using for an incubator? With or without fan? What are you using for temp? Have you calibrated your thermometer and if so, by what method? I'd strongly suggest that you add a hygrometer to your hatching arsenal, and read all of Hatching Eggs 101.

I'm using a digital thermometer and keeping the incubator between 99-100 degrees. Same thermometer I've used from day one. Yes, there is a fan. Yes, there is liquid in the eggs along with the nearly developed chick. The confusing point for me is that I'm doing nothing different these last 3 times than I've done the previous 20+ with the only exception being a new roo and outside humidity.

Often hatching in different seasons requires a change in methods. For instance during the spring/summer I can run dry and add no water holding my humidity in the range that I prefer. Now late fall/winter (especially if the pellet stove is running) it's too dry so I add a sponge to hold my humidity where I like it- but I monitor my air cells to make sure they are still gaining the expected growth.

It is possible that the more you are adding w/o monitoring may be pushing it up too high. Usually after lockdown deaths with "homegrown" eggs signifies either a temp or humidity issue. If your few that are hatching are hatching "on time" then it's likely not the temps and probably humidity. If you are finding excess moisture in them at time of eggtopsy that is a further sign of humidity. I highly recommend a hygrometer just as a guideline, but if you don't choose that path, at least candling and checking the size of air cells will help a lot, and it'll let you know that the eggs are loosing enough moisture.

You also have the possibility of egg shell quality changing, which would also change the rate at which the eggs loose moisture.

And

Thank you for the advice. I'm. Not opposed to a hydrometer, I've just never used one and had what I think is really good success until I tried to incubate this fall. I guess I will get a hydrometer and see if that helps. I also didn't think about the egg composition either. Spring and summer they are free range, this time of year they are penned up and are fed feed. So maybe that's part of the problem too none the less, thanks for giving me things to think about and to try!

ChickenJesus said:

Thank you for the advice. I'm. Not opposed to a hydrometer, I've just never used one and had what I think is really good success until I tried to incubate this fall. I guess I will get a hydrometer and see if that helps. I also didn't think about the egg composition either. Spring and summer they are free range, this time of year they are penned up and are fed feed. So maybe that's part of the problem too none the less, thanks for giving me things to think about and to try!

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You are welcome.