All of whom would not be harmed by outlawing the indiscriminate use of antibiotics in agriculture.
Right now we have a situation where people raising cattle can make more profit by using antibiotics, this drives down the cost of meat to where farmers raising cattle naturally can't compete on price (and must charge a premium for antibiotic-free meat).
If the laws were changed, no one would use antibiotics, consumers would pay an extra 50 cents / pound of beef and the farmers would remain equally profitable. In fact, it might make the midwestern family farm viable again, right now they can't compete with the massive cattle lots, but such regulation could make raising 10-100 head of cattle a worthwhile endeavor again.