I have 2 skittery horses as my haylage is a bit wetter this year. I have been advised to use Yea-sacc and started it today. 100g daily for 1 week, then down to 50g a day.
Increase back to 100g daily if changing onto new grass, or other 'exciting' event.
I bought the farm-pack, which is the same stuff, but in a 20kg bag, and works out cheaper.