And much of it at the time was vitamin D2
PDF is attached at the bottom of this page
Infant formula 40 to 100 IU of vitamin D per 100K Calories
Apparently need 100K calories per kg, which is 454 K calories per lb
So, a 10 lb baby getting 4540 K calories of formula would get 182 to 454 IU of vitamin D
Every 2-oz. of Similac Advance contains 60 IU of vitamin D