Hi mjg,
Goodness, is it that time of year again? My Sussex will be doing the same thing any day now, I expect!
You are right to want to help her to break the habit, as she's too young to hatch eggs and presumably you don't want chicks anyway. Going broody is a Hormonal process, and in order to reverse this you have to keep her out of the nestbox, in the light (because light stimulates a return to lay and a dark comfy nestbox promotes broodiness.) The usual advice is to isolate the hen in something like a rabbit hutch or dog cage with a wire mesh floor and no bedding. In warmer times of the year, you can prop this up off the ground and leave her there overnight, but it would be a bit too cold and draughty at the moment I think.
Could you possibly fence off part of your run with netting, so she can see the other birds but not get in the coop or nestbox during the day? When they go to roost, allow her in the coop for shelter, but put large plastic flower pots or boxes in the nestboxes, to block them off so she has to perch. Remember to remove these next morning, when you put her back in her separate area, so the other girls can lay their eggs. You may need to go down after dark to check whether she's cuddled up on the floor, in which case move her on to a perch. The mild stress of all this change in her routine, plus the removal of comfy conditions, should enable her to forego her dreams of maternity within a few days. When you think she's getting better, maybe this weekend, try letting her out with the other hens after lunch and watch to see if she bolts back in to the coop. If she does, it will be back in the 'sin bin' for another day or so. With practice, when you know the signs, you can instigate treatment at a very early stage, when it will be quicker and easier to break her. If you leave it, she will just sit and sit and lose condition, to no good purpose.
I expect you will get quite used to this little game over the summer, as gold tops do love going broody and make excellent Mums if allowed. Good luck, and please let us know how you get on.
