Is chalav isha that was milked on Shabbos (b’heter) muktzeh?
The status of mother’s milk that was milked on Shabbos involves a dispute among poskim.
Most authorities write that it is considered muktzeh, and besides feeding a baby who requires the milk it should not be moved.
The main question is whether the prohibition of mashkin she-zavu will apply here (because there is certainly no dechiyah beyadayim involved).
The Tur (305) mentions the prohibition concerning milk, and the Mishnah Berurah (305:72) likewise mentions it; however, according to the Ramban (Shabbos 144b) the prohibition does not apply to milk.
Some poskim also raise the concern of nolad, which depends on the precise definition of nolad.
See Shut Rabbi Akiva Eiger no. 5 (lenient); Shulchan Aruch Ha-Rav 305:32; Tehila Le-David 328; Toras Ha-Yoledes Chap. 41, note 2; Shut Shevet Ha-Levi 8:80.