My big 17 hand boy gets 2 tablespoons of turmeric 10 grinds of black pepper and a big glug of linseed oil. If you are feeding your mini Shetlands I would start off with a teaspoonful, a couple of grinds of pepper and a little splash of either linseed,coconut or olive oil. I just throw it all into his feed and mix it up.
As he is not getting much to eat during the summer I am looking into making it into biscuits and feeding him a few of these each day.