what are the medicines or antibiotics used?
Outside United States
This is a VERY vague question. Can you make it more specific.
See the article on feed additives - https://poultry.extension.org/articles/feeds-and-feeding-of-poultry/feed-additives-for-poultry/
The use of antibiotics is highly regulated in Canada, United States and Europe which limits what can and cannot be given to poultry to prevent or treat a disease. I have no idea what the regulations are where ever you are located. This is a USA based resource.