Easy fix, buy a rubbermaid type tote with a well fitting lid to transport your feed in.If you need to buy from that same store, maybe you can open the bag and check before you drive away. I'm sure it would be awkward to transport an opened bag home, but at least you would know if it was suitable, or if you need to buy something different before going home.
And if it is bad, you can return it and get your money back, and the store can complain to whoever shipped them buggy feed.