For decades, factory farmers have laced animal feed with antibiotics-- nominally to promote growth, but also (in my view) likely as a prophylactic measure, given the extremely cramped and unhealthy conditions for animals in modern industrial agriculture.
Anyone with a serious background in bioscience and/or biomedicine can tell you that this is a terrible idea, since it is a virtual cornerstone of modern molecular biology, that resistance to antibiotics develops and spreads rapidly in micro-organisms. Large-scale use of antibiotics leads therefore to the generation of superbugs -- disease agents with resistance to multiple antibiotics.
Given that antibiotics are in fact miracle drugs, and represent the reason why a broken blister, or an unfortunate scratch, need not prove fatal if left untended, and given also the difficult path to their development, it is of key importance to public health that we guard the efficacy of those we possess. I am also old enough to remember parents of friends, who died of tuberculosis in the early 1950's, before the availability of streptomycin.
In light of all this it is good news that the FDA will likely attempt to ban the routine use of tetracycline and penicillin in animal feed. Of course agriculture industry trade groups will cry out that the danger is unproven; this argument contradicts every known biological fact and does not even rise to level of stupidity.