[Griff]

Goat Milk?
Most experts claim that the best kefir is made from raw goat’s milk, but cow’s milk also works, even if it has been pasteurized. If fact, people have made kefir from soy milk, coconut milk, and even fruit juices. But kefir grains differ in the combinations and proportions of bacteria and yeasts they contain, so not every grain is compatible with every food.

It sounds like the starter for kefir is pretty vigorous and should be free of nasty grains etc. I'm going to put Pete on this when we get milking again next summer.