Crowing Hen

Hmm it could be that your hen is changing sex believe it or not this can happen usually with older hens who have come to the end of their laying lives.  Hens although they have two ovaries only produce eggs from the left one usually and if this gets damaged for example by disease or an infection the right one can become active but take on the role of a male testicle.   They will then start to acquire male characteristics.  They stop laying grow male plumage and can start to crow as well as attempting to mount other hens.  I've had a LS which did this and she used to be an excellent layer.  She died after a while too.  It's not common but not particularly rare either.  Some people have postulated that this occurs where there is no natural cockerel.  However I think this is just speculation as most flocks of chickens are solely female.  If there were some sort of predisposition in chx genes to produce a cockerel you might expect it to be more common than it is if it's a survival thing.

Of course it might not be this and if she does it after laying it's called exaulting and is normal behaviour to announce to her fellows that she has left the nest after laying.  It's not quite the same as a cocks crow though.  A sort of ascending reapeted cresendo which ends with a loud sustained squawk.
HF

Thank you for your replies. Glad im not going insane and that im not the only one thats experienced this. The normal sounds chooks make after egg laying is nothing like what she was doing plus she has not laid any eggs for a couple of months after a week of being broody. I hope she stops soon.