Is rat food a no-no?

I got my first chin a week and a half ago. He seems happy with the food I'm giving him (it's specifically designed for chins), but I have a question. Before I owned Bentley I had two rats. The rats died of old age and I still have some of their food left over in an airtight bag. Would it be safe to give this rat food to Bentley, or should I toss it out and let the squirrels have it? Any help y'all give me will be greatly appreciated; I love Bentley and I don't want to make him sick with the wrong food, but I also want to give him a little variety so he won't be bored with what he's got.