Hi there! My children are all on fresh cows milk too!
Truth is we just gave the milk when they demanded it. Nutrition is okay as long as they’re getting right amounts of fruits, veggies, grains, proteins and such. If you really want to be sure about the minerals and vitamins I Guess you could start him on a supplement (with your Paed’s advice of course). Our kids start on cod liver oil as soon as they hit the one year mark. Not the orange flavoured one tho, the original. We find they fall sick less often and it really boosts their immune system.
The childcare should be okay with using a cup and maybe you can provide straws? Alternatively give them the small Meiji bottles to refrigerate with straws. Then it’s disposable? That’s what my daughter’s school did.
Hope this helps!