Here are some papers about antibiotics used in poultry and how to decide what to use.

American Association of Avian Pathologists Guidelines to Judicious Therapeutic Use of Antimicrobials in Poultry
www.avma.org/scienact/jtu...ltry00.asp

APHIS paper about antibiotics used in US and Britain
"Antibiotic Use in U.S. Livestock Production"
www.aphis.usda.gov/vs/cea...biouse.pdf

Oxytetracycline transfer into chicken egg yolk or albumen
www.ncbi.nlm.nih.gov/entr...t=Abstract