Anyone have an insight into the use of antibiotics in farming today?

Used in both dairy and beef farming - excessively. There are restrictions on using milk/meat from animals which are undergoing treatment, as to how well those restrictions are enforced is another story. In the pig farming sector enforcement is hopeless - something like 23% of pork sold in markets contains trace antibiotic or other medication. In the milk sector its hit or miss - if they check your milk and there is trace they will stop buying for at least 2 weeks. What are the chances of been "spot checked"? Quite small in reality but its not worth the risk, but farmers still take the chance on a regular basis.

Use of antibiotics and other meds' in the animal sector is not quite as bad as the use of chemicals in the crop sector - but theres big scope for improvement/education and enforcement.

I had heard of overuse of them in the shrimp farming industry as well. I don't remember the details, but a google of the terms below resulted in numerous papers on the subject.

"overuse of antibiotics in Thai shrimp farming"

At a glance, it looks like many of the papers were more concerned with Vietnam and China and Thailand was often a subsequent mention.