I confess I have not read 1100+ pages but I have a question, if it has already been addressed I'm sorry.
I have a hen that is a first time broody (for her and me) she just has 2 eggs (horrible heat here over 100) so have just let her keep the two. Anyway I have eggs in the incubator that will hatch before hers are ready (if they even make it w/ this heat) so how old can I introduce chicks to this broody and her raise them???
Introducing chicks to a broody is trickier then giving her eggs to hatch. A lot of the time it depends on the breed and temperment of the broody as to whether things will workout.
The way a hen acts normally may be different from her broody state. My EE Smokey was flighty and standoffish before she was broody, but gentle and approachable during broody. She readily accepted all changes to her eggs (her 1st set were duds so I gave her shipped eggs which extended her hatching time) and nest (moved her three times during the daylight hours). Once she was done being broody around the chicks 4th week she was right back to same old mean Smokey.
If possible you may consider letting her finish the hatch by giving her all the eggs at day 14 from the incubator. She will manage them and hatch them around day 19 or 20. The two she is sitting on will most likely be abandoned if they are lagging behind the incubator eggs by greater then two days.
I've given eggs that were on day 14 in the bator to my pullet that was only sitting for a week. She hatched them a week later and raised them just fine. You can shorten and lengthen their sitting time but the eggs will still need 21 days or so to hatch.
If you must give her chicks make sure to remove any eggs she is sitting on at the same time unless they are due that day. Otherwise she will most likely abandon the unhatched eggs in favor of the chicks. My broodies will only wait a day for the unhatched ones.
People have had various levels of success putting chicks from 1 to 3 days old under the hens at night. However a few have even slipped in week old bantams and somehow managed to have the babies and hens get along. That scenario is rare. The issue past a few days old is more about whether the chicks will listen to the hens then whether the hen will accept the chicks.
A few have experienced the hen rejecting and even killing the day old chicks that she finds under herself in the morning, so be sure to check status of chicks and hen in the morning.
Eggs under her are less of a crap shoot then chicks. The hens can sense their chicks by sounds and smells even before they hatch. They can tell who owns which chick even when we can't. I've had my broodies fight over the babies and the babies knew which pullet was their mom from day one. So for a hen to accept a chick she didn't hatch she has to really really really want to be a mom. Not always the case with first time moms.
Let us know how things work out!
