I have a very fussy eater and I struggle to get him to eat Global Herbs supplements which is really frustrating because i think they're great. One trick which has worked, although is incredibly tedious is to grate carrots, apples or pears into the feed.
For the first time in four years my old mare is off of her Becotide/Ventolin inhalers for COPD thanks to Global Herbs Airway Plus powders. I have a young horse who came to me last Christmas with a couple of sarcoids which were gone after six months on SarcEx and an eventer who had a very stressy stomach which is much better with a pinch of Black Salt every day.
My mare really doesn't like Global Herbs stuff either, although I think they are brilliant products.
I now tend to use products from www.silverliningherbs.co.uk and have never had a single product with her eating them, plus so far anything I have used has worked brilliantly.