"If you don't specifically buy antibiotic free meat, you will buy meat with antibiotics in it."

The FDA has control check on the processing line when livestock is processed. This means that the likelihood of any "antibiotic filled" animal to make it through is slim to none. If by chance a ranch or feedlot gets flagged by FDA, they will be fined with a bill in the thousands. This type of flag will make it difficult for that ranch to ever sell livestock in the normal market again. This is only one of the incentives for ranch owners to stay in the clear.

"Antibiotics are used to promote growth"

This statement is false. Antibiotics are used to treat an illness. Yes an animal might gain weight after treatment. But that is because when we are sick we tend to not eat as much. Once you start to feel better, it stirs up your hunger. Antibiotics are and have never been used to promote growth.

What happens to the animal on an antibiotic free farm when it gets sick.

Let's do a comparison example. If your child got sick what do you normally do? Take them to the doctor and if he prescribes a medication for them you would provide the correct amount to treat the illness. This is the same way with the livestock industry. Most antibiotics and medication in general are a prescription based. Therefore, a vet will need to sign off on the treatment of the animals. While most ranches will treat the illness and move on, antibiotic free farms need to move that animal off site to another ranch. Some of the time they have a secondary place where those treated animals go to live out their life. Not treating a sick animal is inhumane.