Grazing on Federal Lands

One of the unknown travesties in the United States is the Federal Government's subsidies to large Corporate Ranches to allow grazing on Public Lands and little or no cost.  I just don't understand why this is necessary especially since this land was set aside to preserve it in its natural state.  However, for those folks who are not familiar with the issue, when cattle graze they destroy the natural plants that took thousands of years to build and lay waste by dumping in the streams and waters, polluting them.   Recently, being a member of Sierra Club's Grazing Team I received a video which outlays an even greater tragedy.  It seems these Corporate Ranchers who no doubt are the buddies of the politicians are supposed to control breeding and predator control (you know foxes, wolves, mountain lions, coyotes, prairie dogs etc. who are supposed to be free on these public  preserves.) get the Federal Government to do it for them.  Here we are trying to save Mother Earth Ship from destruction and our government is doing its best to destroy it.  You can see the video on YouTube: http://www.youtube.com/watch?v=eNH1IR94gls