I have to agree with FS and MLC. There are many many reasons why it would not be a good idea to give antibiotics to any animal or human who is not sick, and in need of them to clear up a specific diagnosed bacterial infection. There are plenty of other experiments that you can do with your chicks that would be fun, and have measureable results. How bout working on an experiment on chick intelligence? See if you can teach them to peck at a specific shape or color for food reward. See how long it takes, or even if you can teach them how to complete a maze. Divide the group in half, and feed one group chick starter only, and give the second group fermented feed, or a different type of feed. Put your thinking cap on, and see how many other ideas you can come up with that don't involve giving medication to your chicks. Any experiment you come up with should have the #1 criteria of doing no harm to those chicks. Using antibiotics would be harmful. I wish you the best with your science fair. Just the act of hatching eggs should be able to count towards the science fair. Perhaps you could wash 1/2 of the eggs, and leave the other half with the natural bloom.