Cattails

[TBlue1@aol.com]

Does anyone know why horses love cattails so much?
My vet says they're 'self medicating' but doesn't know for what.
I can't find it in any books. All I can tell is they'll only eat them
late winter when theyre really brown and brittle, and they love to
just munch away!
This is the sixth winter, so I'm assuming the cattails don't do any 
harm, as none of my horses has ever had any health problems.
But would really love to know just why they like them so darn much!
Thanks!
Tracy....Arbus, Bud and Diego