I'd be scared that it would cause constipation in the chins. The amount that would even come close to being acceptable would be so tiny that it wouldn't be worth it to even buy a small amount.
In the past I have had some really *smart* bring me rescues that have been fed nothing but bird food because "they like it" and "they do really well on it." All of those chins had skinny little droppings and problems defecating. It's one of those things that I can see causing bad constipation and possibly prolapse. And, you can bet that if you put it in with a chin they would go right for it and eat every bit that you give them.
So, it's probably not a good idea to use it...or at least I don't think that chins can have normal digestion if given even just a little too much.