Hello. Lockdown for chickens is considered days 19, 20 and 21 and for some slow growers even beyond those days.
Here is a link from a BYCer that explains what to do during this time. It will depend on how you are hatching-wet or dry. Most (I use this liberally) use wet hatching method in which case you will bring your humidity up.
This will also depend on what incubator you are using. I believe some of the new digital incubators this may be automatic. Someone can correct me if this is wrong.
all i got is a lg still air incubator with the egg turner in it my tep is 100-102.3 my humidity is 34% i know on lock down time you up the humidity to 60-75% and you take out the egg turner so ty for the help
A lot of people get confused about how to tell when lockdown is. Intuitively, you'd thing day 1 is the day you put them in the incubator, but that is not the case.
An egg does not automatically have one day's worth of development one second after it is put in the incubator. It takes 24 hours at incubation temperature for an egg to have a day's worth of development. Lockdown should be after 18 days of development, not 17 days and one second.
For example, if you set the eggs at 7:00 pm on Tuesday March 15, the egg has had one day's worth of development at 7:00 pm on Wednesday, March 16. It will have had 7 days worth of development at 7:00 pm Tuesday March 22. It will have had 18 days worth of development at 7:00 pm on Saturday, April 2. The eggs should hatch on Tuesday, April 5. An easy way to remember hatch day is that chicken eggs should hatch on the day of the week that you set them, in this example Tuesday.
Hatching is not an instantaneous process. The chick positions itself in the egg and internal pips. Then, when it is ready, it external pips. It rests, sometimes for a very long period of time, but also absorbs the yolk, blood vessels dry up and it readies itself for the nest step after pip. The next visible step is zip, where it opens up the egg shell. Then it pushes the shell apart and a wet helpless pitiful looking chick is lying there, totally exhausted. But before long it hops up and starts playing rugby with the unhatched eggs. All eggs do not hatch at the exact same time. There are several different possible reasons for this. Sometimes my hatches are over 18 hours after they start. I have had them go on for more than 48 hours. A chick can go three days without food or water, so you do not need to be in a huge hurry to open the incubator.
Eggs do not necessarily go through this process after 21 days of development either. Again, there can be different reasons, but the common reason is the average incubating temperature. If the incubator is running a little warm, the eggs will hatch early. If the incubator is running a little cool, the hatch can be a couple of days late. With my incubator running warm, I have had eggs pipping when I lock down after 18 days of development with all of them hatching either day 19 or very early day 20. It is not real precise and can be nerve-wracking, especially if they are a bit late.
Lockdown does not have to be timed to the minute. If you are within a few hours, you are plenty close enough. I think it is just good practice to try to get it right, but it is not absolutely required.
What is lockdown? There is a lot going on inside that egg during the last few days. You no longer need to turn the eggs. It is very important to turn the eggs earlier for reasons I won't go into, but after 18 days it is no longer required. Also, when the chick pips, the internal membrane can shrink in low humidity and tightly wrap the chick where it cannot hatch. It does not happen every time but it does happen. I've done it. So you raise the humidity during lockdown and do not open the incubator until the hatch is over. That is why it is called lockdown. You pretend the incubator is locked shut until the hatch is finished.
This gets into the question of what should the humidity be during incubation and again during lockdown. The simple truth is that the same thing does not work for all of us. The humidities that work for me simply do not work for some other people. What I recommend is that you read the instructions that came with your incubator and follow those. Or pick something else and stay with it throughout the incubating process, one humidity for the first 18 days, then a different humidity for lockdown. Be consistent throughout the incubating/hatching process. After your first hatch, analyze your hatch and see if you need to adjust something.
I'll tell you what I do, but I am not going to say it will work for you. During the first 18 days I shoot for the lower to mid-40's. When I go into lockdown, I raise it to the mid-60's. When the hatch starts, mine goes up to the mid-80's due to the moisture from the chicks.
I probably made it sound harder than it really is. It is a stressful time, but rewarding when they start hatching. And they are usually pretty tough. As long as you get it close, you have a decent chance at success.