If a mob can be spawned in without AI. It's reasonable to think that merely turning it off under certain conditions would be doable.
Like make it so an animal makes periodic (like every 5 mins)checks to see if it's in a space enclosed by fences and closed gates and make it so that space is the only place they can path to.
Or a magic mod that adds a mesmeriser that attracts their gaze and turns off their path finding completely exept when they are in breeding mode.
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Actually, I think ChromatiCraft has a thing that does, or rather will do, this. At least, that's what I'm assuming chroma.aishutdown is all about. Can't make it, yet, but it sounds quite useful.