N.Y. Comp. Codes R. & Regs. tit. 1, § 1.4 – Method of producing vitamin D milk.

(a) adding concentrate of vitamin D to milk prior to and at the place of pasteurization;
(b) directly irradiating milk by means of ultraviolet or carbon arc rays prior to and at the place of pasteurization; and
(c) feeding irradiated yeast to the cow or cows on the dairy farm.

The following procedures for increasing the vitamin D content of milk to at least 400 U.S.P. units per quart are hereby approved: