Microbiological detection of tetracyclines in 9 lots of animal feed produced in Costa Rica: Infringement of norms and incongruences with the official labeling

Abstract

Considering the environmental and sanitary risks associated with the use of antibiotics in animal production, we used a microbiological method and an analytical method by HPLC to evaluate the presence of tetracyclines in 9 lots of animal feed for swine (n=4), tilapia fish (n=3) and broiler chicken (n=2) produced in Costa Rica. Up to 75% and 67% of the swine and tilapia feed samples analyzed gave positives results using both techniques, respectively. By contrast, the broiler chicken feed samples did not contain any of the three tetracyclines included in the tests. All positive swine feed samples contained chlortetracycline in concentrations higher than those allowed by the Costa Rican regulation. Positive tilapia feed samples contained oxitetracycline in concen-trations equal or greaterthan those detected in swine feed. Inaddition, four samples exhibited inconsistencies between the concentrations of tetracyclines detected and the concentrations specified in their labels. These results justify a stronger monitoring by the producers, consumers and national sanitary authorities.