for your in-lamb ewes it depends on the quality of the hay and when they are due to lamb. I wouldn't feed the ewes until 8 weeks to lambing unless they have no grass at all and even then I would just give them hay or haylage ad-lib. Are the shearlings tups or ewes? if they are tups you should be boosting them with a LITTLE cake and mineral. we feed a 14 or 16 per cent protein up to 1/2lb a head. some of the big breeders will be feeding a lot more and a rich fibre diet such as cabbages as they want big solid tups for sale. We don't feed our hoggs or gimmer ewes except when condition scores go down. commercial breeds will let you know when they want extra feed by following you round the field if you have a cake bag or bucket