In the broader context of dark BL or smut, a "milk factory" often involves "human ranching" or "breeding slave" themes. Common elements include:

As the days turned into weeks, Liang and Meng's relationship blossomed. They would steal glances at each other during meetings, and sneak kisses in the storage room. The other employees at Golden Cream were delighted to see the two young men so happy, and they did their best to support the budding romance.

This novel contains mature themes (non-consensual medical procedures, psychological manipulation, body horror). It is not a fluffy omegaverse romance—it is a dark, queer love story about surviving a system that wants to consume you. For fans of "The Handmaid’s Tale" meets "Given" with a sci-fi twist.

Morning Glory Milking Farm by C.M. Nascosta : r/RomanceBooks

: While technically a "monster romance" rather than a standard BL, it is a very popular recommendation in similar circles for its "milking" premise involving minotaurs.