Occurrence of veterinary antibiotics in poultry manure from two farms in Ibadan, Nigeria: Ecotoxicological implications in manure-amended soil

Veterinary antibiotics are commonly used in poultry farming for preventing diseases and promoting growth. As a result of their incomplete metabolism in poultry birds, veterinary antibiotics are usually excreted and are frequently detected in poultry manures. Veterinary antibiotics in poultry manure applied onto soil may pose serious ecological effect to the terrestrial and aquatic environment. In the present work, the occurrence of three veterinary antibiotics (sulfamethoxazole, sulfadimidine and trimethoprim), categorized as veterinary antimicrobial agents of critical importance, was investigated in poultry manure from two poultry farms in Nigeria. The potential ecotoxicological risk of target veterinary antibiotics in poultry manure-amended soil was also assessed. A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction was adopted for the extraction of target veterinary antibiotics and instrumental analysis was achieved by high performance liquid chromatography. Sulfamethoxazole, sulfadimidine and trimethoprim were quantified in poultry manures from the poultry farms up to 12.7 μg g(−1), 16.1 μg g(−1) and 33.8 μg g(−1), respectively. Sulfamethoxazole and trimethoprim in poultry manure-amended soil presented low risk to Eisenia fetida (earthworm). The ecological effect of sulfamethoxazole for the root length of rice was high in Farm B and medium in Farm A. Sulfamethoxazole presented high risk to aquatic organisms while sulfadimidine and trimethoprim posed medium risk and low risk, respectively to aquatic organisms. The results indicated that residual veterinary antibiotics in poultry manures could have adverse effects on crops after application to agricultural soil. There is a need for effective enlightenment programs for poultry farmers in Nigeria to bring about awareness on the environmental and toxicological impact of the excessive and uncontrolled use of veterinary antibiotics in poultry farming and the adverse ecological implications of poultry manure application on farmlands.