broodmare not eating

Question
I have a broodmare that's 3 months bred, she just started not eating her feed but will eat hay and grass.  Is this common and what should I try?

Answer
Dear Kim,
       some mares don't like the type of feed they get when they are pregnant, try differant brands and flavors. We have a few mares that are drama queens, and will only eat a certain food. And if she eats a food, write it down so if she is ever pregnant again you know what to feed her.
michelyn