Pretty much the whole of the UK is deficient in copper, cobalt and selenium, all of which are required for optimum health.
A very few sheep breeds have evolved to cope with low copper, among them Texels and North Ronaldsay.
Too much copper is more dangerous than too little.
Sheep will in general self-regulate their mineral intake if able to do so. However, sprinkling minerals on feed, mixing minerals with molasses, or worse, soya, all have the potential to encourage partaking to excess.
Hardworking ewes and rams will show evidence of mineral insufficiencies sooner than wethers and other sheep who are not breeding. However, even wethers will benefit from some mineral supplementation. Some of the things which might alert you to mineral deficiencies include :
- browning of the tips of the fleece (different to sun-bleaching)
- other changes in colour of fleece including light bands within the length of a coloured staple
- scabby patches on ears
- brittle wool
- pink staining in the wool
- general malaise / ill thrift
- brittle hooves
- lethargic lambs
- lambs wobbly
- lambs with poor appetite for milk
Some but not all of a sheep's mineral requirements will be met by ad lib Himalayan rock salt.
Most of us find that Yellow Rockies is not used, the molassed blocks are generally quite large so may be overkill for 4 pet sheep, and the free access pure minerals are not as easy to use plus may not be available in very small pack sizes.
For sheep which are not working hard, feeding a very small amount (like 1/4lb per head per day) of cake in the depths of winter is a quick and easy way to get a mineral top-up into any sheep. And if it is limited to deep winter, it is unlikely to cause too much condition even on sheep who don't work.
For people with real good doers or who do not want to feed cake for other reasons, then one of the organic-approved mineral licks is a non-feed alternative, as is begging a few doses of a mineral drench from the local farmer. Or you may have a vet who will dispense a small quantity.