It's your right as mommy to do what you think is best for your child! If you prefer your child's milk to have the chill taken off of it, then it's the daycare's job to make you and your child happy! This should not be a strange request for a 1 year old room. If you offer an explanation, it will help them be more understanding. My son drank milk cold, but he wasn't picky about it from birth...about his milk anyway :0) If the daycare won't comply with something as simple as that, I would look for somewhere that will try their best to accommodate you.
I think he'll adjust. Don't make things harder on the daycare people than they absolutely need to be. You'd be surprised how fast he'll get used to it cold. My son drank breast milk (from the breast, so at body temp) alternating with formula (from the fridge or just mixed, so, cool) since he was a baby, and it never threw him. Warming milk in the microwave is an art, also -- you can get hot spots in a cooler base and those hot spots can actually scald the mouth. (That's why they tell you never to heat a baby's bottle in a microwave.) If you say, "But I could instruct them to be sure to shake it up," at that point I think I would say see my comment about not making it harder for the daycare people than it needs to be.
dd (22 months) drank it cold until earlier this week when she started asking me to warm it.
Annie makes a very good point- many daycares have a policy of not using a microwave to warm beverages since it can be dangerous. However, it sounds like they are pretty reasonable and it can't hurt to ask. Inquire whether or not any of the children are similar, and if they have ever had to warm milk for a child. It not may be that the milk is cold- he's probably too busy/active to be bothered with drinking much milk, especially if he just started.
i personally prefer it when she takes it cold, because i will put it back into the fridge if she doesn't finish it and offer it again later. I won't do that if it's warmed.
I think tired makes a good point -- it was his first day, he was excited and interested in everything else --- the activity, the kids and the toys. What's to a boring old cup of milk by comparison? I'd wait a couple more days and see if he doesn't start drinking it before asking the daycare to make an extra effort to deal with his milk especially.
Thanks all for the suggestions! This morning a brought his cup with me and mentioned that the reason for which he's not drinking much milk could be because of the cold temperature. She just said it was not a problem at all because in that case she just uses a crock pot. She just got it out of a cabinet and started getting it ready. She said that some kids just prefer it that way and that there is no problem. All good!