How much antibiotics is in the beef we eat, and what antibiotics are they?

I have many, many sites with info on antibiotics fed to beef cattle (and pigs, sheep, chickens?), but nothing on how much of it ends up in the steaks we buy, or eat at a restaurant. Ditto pork, lamb, chicken, duck, ...

Related question: what are the levels in eggs, milk (cow, goat), cheese, etc?

Apart from the dangers of antibiotic resistance, I have recently become aware that ingesting antibiotics while on (at least some, traditional) chemo regimes makes symptoms worse, and can cause one's digestive track micro-biota to not return to a healthy state once the chemo has gone.