Detection and prevalence of oxytetracycline residues in indigenous cattle slaughtered at Mlandizi slaughterhouse in Kibaha District, Tanzania

Abstract

The presence of antibiotic residues, such as oxytetracycline (OTC), in meat poses health risks to consumers, including the development of antibiotic resistance. The WHO and FAO have identified antibiotic resistance as one of the top global public health threats, partly driven by antibiotic misuse in agriculture. In Tanzania, monitoring of such residues in livestock products remains limited. The present study was conducted to determine the prevalence and concentration levels of oxytetracycline residues in cattle slaughtered at the Mlandizi Slaughterhouse in Tanzania. A cross-sectional study was conducted using 200 tissue samples collected from 100 slaughtered cattle. Muscle and liver samples were analysed for oxytetracycline residues by using a competitive enzyme-linked immunosorbent assay (ELISA) kit (Shenzhen Lvshiyuan Biotechnology Co., Ltd., Version: 2017-04). Detection rates were calculated per animal and per sample. Descriptive statistics summarized residue concentrations. All analyses were performed using Epi Info version 7.2.2. Oxytetracycline residues were detected in 17 out of 200 tissue samples (8.5%; 95% CI: 5.0-13.3%). At the animal level, 14 out of 100 cattle (14.0%; 95% CI: 7.8-22.3%). The mean concentration of residues was 3.8 ng/mL in liver and 2.8 ng/mL in muscle. These values were below the maximum residue limits (MRLs) set by Codex Alimentarius (WHO/FAO). However, one muscle sample had 216ng/mL residues, which is higher than the allowable limit. Liver consumers are more prone to oxytetracycline residue exposure. A proportion of cattle slaughtered at Mlandizi carried oxytetracycline residues in edible tissues, while most samples were below the MRLs, the presence of even small amounts of oxytetracycline residues raises concerns about the cumulative effects of chronic exposure. The findings emphasize the need for continuous routine monitoring of antibiotic residues in meat. Addressing both knowledge gaps and economic constraints can help reduce improper drug use