The study was conducted in conjunction with the FDA Denver District Laboratory. 
The Denver District Laboratory was responsible for submitting their results from 
the official microbiological method to the Center for Veterinary Medicine.
Oxytetracycline (OTC) fortified and incurred samples of rainbow trout fillet 
tissue were prepared at the UMESC. Portions of those samples were shipped to the 
Denver District Laboratory where they were processed to determine OTC 
concentrations. Incurred samples processed at the UMESC had OTC concentrations 
of 740, 1588, and 3944 ng/g. Method precision for those samples ranged from 0.5 
to 2.2 %, respectively. The nominal OTC concentration in fortified samples 
ranged from 0.3 to 9.6 ng/g. Recovery of OTC from those samples ranged from 93 
to 96 %.