How long will hen sit on eggs?

[Sandfly45]

I'm letting my chook hatch eggs for the first time. We have a rooster so I figured the 6 eggs she's been sitting on for the last 10 days would be fertile. Candled them tonight and they're all blanks unfortunately. If I get some fresh fertile eggs under her soon will she carry on sitting for the 3 weeks they need or will she get sick of sitting for way too long and abandon them before hatch?

 

[TheFatBlueCat]

You've got no way of knowing for sure, but she probably will. I regularly wait for around 7 days before setting fertile eggs under my hens and I haven't had a problem with them giving up, so they've been sitting for at least 28 days, and I've had them go longer than that. Hens will be hens though and they are governed by mysteries unknown to humans.
I've not had a hen that has just up and stopped even on a failed hatch. I've had to encourage them to leave the nest. You could get an incubator as a back up if she leaves the eggs. Depends how badly you want chicks! I don't want to raise chicks in a brooder so I leave that to the broodies and whatever nature declares to be the outcome is what I (sometimes grudgingly) accept.

 

[Shadrach]

I'm letting my chook hatch eggs for the first time. We have a rooster so I figured the 6 eggs she's been sitting on for the last 10 days would be fertile. Candled them tonight and they're all blanks unfortunately. If I get some fresh fertile eggs under her soon will she carry on sitting for the 3 weeks they need or will she get sick of sitting for way too long and abandon them before hatch?

I would get her off the nest with the infertile eggs and wait until she goes broody again.
People do let their hens sit for more than three weeks and apparently the hens have hatched the new eggs put under her. I would want to be very certain that the hen has maintained her body weight and is healthy before putting any more eggs under her.
If you do decide to let her sit, leave the eggs alone. Don't candle them or play with them or even touch them.

 

[Sandfly45]

Great thanks for the advice! I've managed to source some half baked fertile eggs so I'll pop those under her this weekend and she may have chicks sooner than she expected. I've only ever hatched eggs in an incubator so having a hen hatch her own is a new exciting thing for us all!

 

[Ridgerunner]

I think you'll be fine. Before a hen even starts to lay she stores up a bunch of extra fat. I've butchered enough cockerels, roosters, pullets, and hens to see that difference, it is a lot of fat. That excess fat is mostly what a broody hen lives off of so she can stay on the nest and incubate the eggs instead of needing to be off searching for food. Expect her to lose some weight while broody, that's just fat put there for that purpose. Different hens spend different amounts of time off of the nest so some may eat and drink more than others so that fat may last longer for some than others. I'm extremely comfortable with a broody being on her nest for 5 weeks, after that it may be stretching it. I don't have any science backing up that 5 weeks, it's just an arbitrary number I'm OK with.

Good luck and let us know how it goes.