I can't see how you could feed a powdered vitamin and mineral supplement to guinea pigs unless you sprinkled it on their lettuce or something. It does seem reasonable to create a concentrated pellet though.
Easier than that. Add the powder to water, then mix the water with some Hershey's strawberry syrup to make it taste great.
Doug just brought up a good point, with our pigs already being fed pellets their entire life, would'nt they alreay have some sort of stone possibly forming? Would it have to be a baby pig that does this "test" who has never had pellets compared to those of ours that have eatten them their whole life? Or do our pigs have so many health issues becuase of their previous conditions before coming to live with us? I always feel that a lot of my pig's health issues are becuase of treatment they had before coming here.
I have 3 guinea pigs of my own right now. Tika and Crysania are both under 6 months old, but no idea how old Alpha is. When Alpha finally gives up those precious bundles of energy she's hiding in her womb, I intend to keep any sow pups, as well as give them equally bizarre names.
I'm willing to give it a shot.