The "natural" grassfed program we have been selling our calves to the last two years, do not take the ones that have had antibiotics. They make us sign an affidative stating that they have not had antibiotics, the ones that have been treated, we sell another way. Which is a pain in the butt when there are not many that get pinkeye or something. But the premium we get on the others is worth the pain in the butt.
To me, that is what "natural" branded programs want, no antibiotics.