Any current version.

If a player put more animal in the pen more than the herder can handle. So level 1 build can handle 2 animals at a time. If the player puts 4 animals in there and 3 of them are babies.
The herder will go and kill 1 grown up and 2 babies. Even though the babies will not produce anything. The herder should wait until they are full grown and then kill excess animal. It is stupid to slaughter a baby when it will not produce anything.