Brewers yeast for fly control?

[dreambigpony]

Seems that this year my horse is being bitten like crazy! Whatever fly rug I put on, spray or gel it's just doing nothing.
A couple of people have suggested feeding brewers yeast? Any one do this? And does it make a difference? Thanks

 

[Sussexbythesea]

I give mine brewers yeast routinely and he’s as much of a fly magnet as any other horse so no I don’t think it works at all for that purpose.

 

[Surbie]

I feed it to reduce my horse's reaction to midges - he's got sweetitch I think. He is less itchy on it than off. Still covered in flies when I bring him in in the morning.