One of the companies out there creating 100% Grass-Fed Dairy is Maple Hill Creamery. They had the attached infographic on their website that really explained to me why 100% Grass-Fed is important to me, and to the cows.
That bumper sticker was a great piece of marketing that got the consumer (me) thinking and changing my behavior. I think it was more effective that just saying on a label 100% Grass-Fed!
Source: http://maplehillcreamery.com/whygrass.html