That's one big difference between preserving domestic animal breeds and protecting wild animals. The main purpose of livestock preservation is still utilization. You don't just want to preserve the animals, you also want to find out which genes carry which hereditary characteristics and stabilize them, so you have to use artificial controls.
這也是畜禽保種和野生動物保育不一樣的地方，畜禽保種主要目的仍在「資源利用」，因此不只要保存畜禽，更要找出遺傳特性的基因，加以固定，那就不得不有「人為」的操縱了。