I have been researching a bunch about making my own substrate, and I am particularly interested in making my own Kinshi. Anyways, I looked online and it seems that coffee grounds are popular with oyster mushroom growers. The mycelium seems to take root on coffee grounds particularly quickly, so it seems to be that they should be fairly high in nutritional content. Has anyone tried raising stag beetles with coffee grounds? To be clear I don't intend to use coffee grounds in the place of sawdust, rather as a supplement kinda like how you would add wheat germ to your substrate. Any thoughts?