right, but the milk changes in composition even during nursing, the milk that flows first is different from the milk that flows later. You just wonder if the composition, aside from the most basic parts, can ever really be noted. I agree that breast milk is definitely the best way to go- but, for the baby, not an adult! Supposedly it has over 600 different bacteria strains. Who knows! Try to get some, seriously- I bet it'd be easier than you think, there are lots of wackos out there who stalk breastfeeding forums, etc.
PS- not that you're a wacko! I wonder if it would culture with kefir grains too, as it's not really "dairy", & it's already cultured to some extent. Probably be better off just doing a shot of it a day as opposed to trying to make kefir with it.