ChickyMudder
Songster
In lock down, the increased humidity is said to soften the membrane and egg shell. If you had high heat throughout the incubation the chick could develop faster. If you put them in lock down early and softened the shell by increasing humidity - you could encourage early hatch. Just my best guess.I've read that higher temperature causes the embryo to develop faster, so it hatches earlier, no matter what the humidity is.
Lower humidity causes a bigger air cell, because the egg dries out more, but I have not heard of that affecting whether it hatches early or late.
Why would that make them hatch early?
I thought "lockdown" just meant to quit turning eggs, and leave the incubator closed. There's nothing about that to cause early hatching. Turning definitely does not stop an egg from hatching (evidence: stories of chicks that hatch early while the turner is still running, and of course chicks under a broody hen.)