I just got grains from her--and intend to give them cow's milk. My undrstanding is that it won't be a problem. I do not like goat's milk.

Don't think it matters what kind of milk the grains you buy have been raised on... bought mine from Kefir lady online and I don't like goat's milk so I've been feeding them raw cow's milk for the last six months and they have grown and multiplied too many times to count. All my kefir-loving friends now have their own grains thanks to her. I even made some coconut water soda with some of the grains for a while and then stopped an switched back to making milk kefir again with no problems.