Not entirely sure what it could be used for, perhaps a deterrent of sorts?
So I've been thinking about the animal's living conditions tend to be pretty crappy. Overly packed, their children's corpses rotting only a few feet away from them, mass inbreeding, etc. But what if there was a mechanic that made these conditions bad towards the animals' growth?
So here's the idea, if an animal's conditions are crappy, their Q growth declines and their stress levels rise, while if it's better (less packed, perhaps let us pet the cows? (Yes I know that's getting into Harvest Moon territory)) their Q rises?