title: Screening of antibiotics and chemical analysis of penicillin residue in fresh milk and traditional dairy products in Oyo state, Nigeria.
abstract: OBJECTIVE
  There are global public health and economic concerns on chemical residues in food of animal origin. The use of antibiotics in dairy cattle for the treatment of diseases such as mastitis has contributed to the presence of residues in dairy products. Penicillin residues as low as 1 ppb can lead to allergic reactions and shift of resistance patterns in microbial population as well as interfere with the processing of several dairy products. Antibiotic monitoring is an essential quality control measure in safe milk production. This study was aimed at determining antibiotic residue contamination and the level of penicillin in dairy products from Fulani cattle herds in Oyo State.
  
  
  METHODS
  The presence of antibiotic residues in 328 samples of fresh milk, 180 local cheese (wara), and 90 fermented milk (nono) from Southwest, Nigeria were determined using Premi®test kit (R-Biopharm AG, Germany) followed by high-performance liquid chromatography analysis of penicillin-G residue.
  
  
  RESULTS
  Antibiotic residues were obtained in 40.8%, 24.4% and 62.3% fresh milk, wara and nono, respectively. Penicillin-G residue was also detected in 41.1% fresh milk, 40.2% nono and 24.4% wara at mean concentrations of 15.22±0.61, 8.24±0.50 and 7.6±0.60 μg/L with 39.3%, 36.7% and 21.1%, respectively, containing penicillin residue above recommended Codex maximum residue limit (MRL) of 5 μg/L in dairy. There was no significant difference between the mean penicillin residues in all the dairy products in this study.
  
  
  CONCLUSIONS
  The results are of food safety concern since the bulk of the samples and substantial quantities of dairy products in Oyo state contained violative levels of antibiotic residues including penicillin residues in concentrations above the MRL. This could be due to indiscriminate and unregulated administration of antibiotics to dairy cattle. Regulatory control of antibiotic use, rapid screening of milk and dairy farmers' extension education on alternatives to antibiotic prophylaxis, veterinary prescriptions and withdrawal periods are recommended to prevent residues.
authors.affiliation: Pathogenomic and Proteomic Laboratory, Paul Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA; Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Isaac Olufemi
authors.initials: IO
authors.lastname: Olatoye
authors.affiliation: Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Oluwayemisi Folashade
authors.initials: OF
authors.lastname: Daniel
authors.affiliation: Analytical Laboratory, Nigerian Institute of Science Laboratory Technology, Ibadan, Nigeria; Department of Chemistry, College of Arts and Science, Washington State University, Pullman, Washington, USA.
authors.forename: Sunday Ayobami
authors.initials: SA
authors.lastname: Ishola
keywords: Oyo state; milk and milk products; penicillin residues; public health