Good for the BLM. I recently witnessed one of these gathers, and there is indeed no impact (other than a positive one for wildlife).
Too bad she doesn't love feral horses enough to learn about them--that they suffer in the wild, esp. Nevada, and that they cause suffering in native wildlife. And too bad her prediction that no more will be born can't possibly come to pass. http://www.rgj.com/apps/pbcs.dll/article?AID=2011106060325