But whats mercury got to do with the cow's...

Some experts call for removal of more heavy metals from waste
before it is used as feed or fertilizer..

Besides the hormones residues that are found in cow manure..
And the cows themselves..
Also are found arsenic , lead , cadium and mercury and it
can collect in cattles's organ's and tissues..

It's not the cows that are the biggest problem..
It mankind..
As how did all thoses contaminates got into the cow's in the first place..
Perchlorate as well...

I say when it comes to cow manure..
Incinerate it.. Burn it...
Before it reaches our waterways and decomposes and harms us all.
Like thats the only contamination out there anyway..

http://news.nationalgeographic.com/news/2006/08/060818-ethanol_2.html