[Qantourisc]

In a way this is surprising to me. Shouldn't this destroy the gut flora, making it harder to digest/use the food ? Then again their entire gut flora might be anti-biotic resistant ....

[maxerickson]

Several of the antibiotics in use as feed additives act selectively, changing the mix of microorganisms rather than destroying them all.

I swear I'm not a shill for big ionophore, but this is something they do in ruminants, they shift the mix away from one that tends to lead to "bloat" when the animals are fed a lot of grain.

[bodski]

Gut flora in humans appears to have a significant influence on weight gain/loss. Perhaps ABs fed to livestock tilt towards weight gain.

[IslaDeEncanta]

Actually, that's often the case with cattle.

[Fomite]

Cows can have pretty intensive levels of antibiotic resistant gut flora.