Maybe maybe not. I think to establish a realistic anti-breeding system, you'd have to first establish a realistic breeding system.
Not necessarily. Castration is in the dev notes as a Req, while realistic pregnancy only warrants a Bloat:
# Req509, CASTRATING ANIMALS, (Future): Dwarves should be able to castrate male animals. Spaying female animals might be beyond the ability of dwarves to do reliably.
# Bloat46, PROPER PREGNANCY, (Future): Currently creatures become pregnant from a distance, although it does do a gender check at least.
Castration would certainly be simpler to implement than actual mating etc.
Yay! I'm pro castration--
1) It's a method of controlling reproduction in game as opposed to in init, which makes it content.
2) It gives Animal Caretaker something else to do.
3) If inherited traits (simple or otherwise, personality or statswie) ever come into being, this could have interesting consequences.
4) Pet owners could have an affinity for virile, apathetic, or not. Since your dealing with only males, the affinity for virile should be quite low to preserve the intended function of castration.
4) An 'IsCastatable' tag for males would be great fun, and if enabled for dwarves could have horrifying consequences post relationship arc (Eg, sweet on the Baroness and the fortress guard comes for you balls, mistreat your wife, hope she doesn't find that *Copper Dagger*), and for Dwarven Justice (Instead of beatings and hammerings, throw an odd castration into the mix). Albeit, if applied to dwarves, some female analog should be found-- Maybe a scarlet letter branded on...