I believe that another thing that effects the taste of beef is how the cow is slaughtered.
I was at a shooting match out in Garden City, KS, and the host was a rancher. On the last day of the match he walked up to a cow that was calmly grazing in the field, and shot it in the head. It fell over like a rock, then he cleaned it, and prepared it as a slow cooked BBQ. It was, without a doubt, the best beef I've ever tasted. He explained to me that the stress of the transportation to the slaughterhouse, and the environment of the slaugterhouse paniced the cattle, and it changed the way the meat tastes. I have no reason to disagree.
Mark