Iodine Supplementation

Low levels of iodine can cause all sorts of subtle (and not so subtle) problems in sheep production.
Brassica feeding can also run down iodine levels. If your farm is right on the coast you may be OK, but towards the valley there is little, if any, extra iodine available.
The most noticable effects of low iodine are on poor lamb survival. If you have a solid vaccination programme in place, but still appear to have low lamb survival (Scanning to Docking gap), consider some form of iodine supplement pre lambing.
Potassium iodide oral drenches are cheaper and generally effective methods, but often need to be repeated (See your vet for a recipe and supplies).
Flexidine injection is an alternative - A single 1.5ml dose under the skin injection prior to mating (~February for MA ewes) should see them (and their lambs) right for the season.