Oxytetracycline Residues in Cattle and Pig Carcasses: A Study of Muscle, Liver, and Kidney Tissues

This study aimed to evaluate the levels of oxytetracycline (OTC) residues in cattle and pig carcasses in Kaduna metropolis, Nigeria. A total of 300 samples (150 each for cattle and pigs) comprising of liver, kidney, and thigh muscles were randomly collected from cattle and pigs in selected abattoirs and slaughter slabs in Kaduna metropolis. An adapted microbial inhibition test using Bacillus subtilis and high-performance liquid chromatography (HPLC) was used for residue analysis. The results showed that 40.0% of cattle and 26.6% of pig samples tested positive for antimicrobial residues. The sampled tissues had both liver and kidney from Kakuri as the highest at 53.3% (8/15) followed by muscle at 46.6% (7/15) for cattle while liver from Ungwan-Television and Kurminmashi had the highest 33.3% (5/15) followed by liver and kidney from Narayi 30.0% (3/10) in pigs. The highest mean concentrations of OTC residues in cattle tissues were found in the kidney from Kakuri (1541 ± 417.3 µg/kg) and in the liver from Kakuri (1526 ± 314.2 µg/kg) though not significant (p > 0.05). In pigs, the highest OTC residue concentration was in the liver (470.5 µg/kg) which was below the maximum recommended limit. A retention time of 1.96 min was observed for the HPLC analysis of samples. The study highlights the significant presence of OTC residues in livestock, raising concerns over potential public health risks, and antibiotic resistance. The findings emphasize the need for stringent regulatory measures and residue monitoring to ensure food safety and public health protection.