Well i probably need to clarify on previous posts..
I have 5 Cornish game and 5 Light Sussex in the Bator.
We are a family of 4 (2 adults and 2 kids - 5 and 2) so we don't need MASSIVE birds for the table. they are all for roasting purposes and the giblets will be kept for making stocks / gravy etc. as of this we only want an end weight of about 1.5 Kg or 3-4 Lb birds, some i will leave to get older so we will have some big birds if we have family over :O)
So really I need the live weight of a bird to be 5 Lb
I am hoping that the slaughter time will happen BEFORE the cocks start crowing, what are the chances of this happening? how old will my birds need to be before they meet the axe?
I've not had a cornish x crow significantly on me yet... but if I understand right, you are planning on eating excess "dual" type birds. They'll almost certainly be crowing before they hit 5 lbs live. Go by age instead of weight on those guys.