Responsa sur Shabbat 8:11

I also asked [in my dream] about those who hire shepherds to watch their animals, and on Shabbat they go and milk the cows and start curdling the milk to make cheese, all while in the employment of a Jew. It is well known that we are not allowed to have anyone in our employment doing labour on Shabbat with our possessions. If so, how do we allow them to milk and curdle, since milking is prohibited under the category of mefarek, separating, while curdling falls under the category of boneh, building. I asked these four questions together.¹See Hagahot Maimoniot, on Mishneh Torah Shabbat 8:10, where Meir of Rothenburg and the Gaon Rav Cohen Tzedek rule that one can ask a non-Jew to milk. Kol Bo 31:21 also quotes Meir of Rothenburg as saying that the milk needs to be bought back symbolically, and also cites Rabbeinu Peretz who says that the milk cannot be used on Shabbat itself.