Yes, because the darker cows absorb more solar energy while all-white cows reflect it, thus producing less methane.
I'll bet you could get cap & trade credits for going with an all-white herd.
A lady came up to me on the street and pointed to my suede jacket. "You know a cow was murdered for that jacket?" she sneered. I replied in a psychotic tone, "I didn't know there were any witnesses. Now I'll have to kill you too."
Buffy
