At the moment there is no brake on the number of pigs, butterflies and chickens we hatch from eggs in a street or backyard but what if the game had natural predators for these and other domesticated animals? We could have foxes for chickens, frogs for butterflies and wolves for pigs. These would be rare in a balanced environment but where numbers increased then the chance of a wolf, fox or frog passing through a street devouring lifestock would also increase.
To offset this we could also have a few objects to help. Whistles, tin-cans and sticks to chase the wolves and foxes, jars to catch the frogs. These would form part of an animal husbandry skill.