A lot of morons out there perpetuate the myth that antibiotics are given to healthy animals (they aren't unless the herd has been infected and they need to inoculate to prevent spread of disease)
And there are even more morons out there that never check their facts. It took me less than a minute to find a Dutch governmental report, Health Council of the Netherlands: Committee on Antimicrobial growth promotors. Antimicrobial growth promotors. Rijswijk: Health Council of the Netherlands, 1998; publication no. 1998/15., on the widespread use of antibiotics in the livestock industry to promote growth.
Of course they don't call them antibiotics in the industry, they are labelled as "antimicrobial performance enhancers".