[Marches Farmer]

Are they pregnant?  If it's likely you'll be keeping them in until lambing probably worth sectioning off the bit you'll use for mothering-up pens so you can get them inthem  once they show signs of being close to lambing ads they lamb down onto clean bedding to reduce the risk of clostridial diseases (there are plenty of strains not in the Heptavac jab), watery mouth and joint ill.