When grain goes bad it gets really powdery and dry. I learned this because I got a bad bag of grain and luckily Pam (my barn owner) gave me her opinion. On her advice I took a bag of it to Diess Feed and Seed in Eugene and talked with Mike (the owner). He told me that it was absolutely bad and to throw it away.
Mike said a few days before that the high fat grains are hard to keep around in the summer because they go bad very quickly. Especially the ones with flax in them. He orders it from an air conditioned warehouse, but his place isn't air conditioned (and most feed stores I have been to aren't). So, word to the wise, don't buy your high fat content grain in bulk, buy it as you need it.
This may be the reason Precious keeps going off her grain, so I am going to go buy her a new bag. I have always bought 3 or 4 bags at a time and stored them. I still have one left that I bought in July, so I think it may be spoiled after sitting in my van for some time (in the heat) and then in the tack room.
I learn something new every day!