You can find raw milk at health food stores. It’s labeled not for human consumption, but that’s for legal purposes.
They say you can use skim milk, but I believe any process other than a filter kills everything that is truly beneficial.
Try it yourself. I plan to when my outdoor grow starts. I plan on using raw, but perhaps I’ll try a comparison. Skim would be cheaper since raw costs around $10US for a half gallon here.