Double, double toil and trouble. Check what’s in your next craft lager. It may not be eye of newt or toe of frog. But it could be close.

Hoping to stand out in a competitive market, brewers are throwing all kinds of things into the kettle: broth from a caramelized moose’s head, bull testicles, grasshoppers and a pinch of yeast from a beer maker’s beard. Yes…that’s right…his beard.

To...