DETERMINATION OF ANTIMICROBIAL RESIDUES AND THE EFFECT OF HEAT TREATMENT ON RESIDUAL CONCENTRATION OF SOME ANTIMICROBIAL DRUGS IN FRESH COW MILK IN ZARIA, NIGERIA

DETERMINATION OF ANTIMICROBIAL RESIDUES AND THE EFFECT OF HEAT TREATMENT ON RESIDUAL CONCENTRATION OF SOME ANTIMICROBIAL DRUGS IN FRESH COW MILK IN ZARIA, NIGERIA

Abstract:

Veterinary drug residues are a global health concern in many countries, with developing countries reporting high occurrence of residue contamination of edible animal products beyond FAO/WHO permissible levels.The occurrence of antimicrobial drug residues in milk in Zaria and environ, and the effect of heat treatment on residues of some antimicrobials was investigated. Three hundred fresh milk samples were collected from local Fulani milk producing herds in 11 villages and areas within Zaria and environ. Each milk sample, was screened for the presence of antimicrobial drugs using Delvotest SP-NT®. Antimicrobial residue-free milk was spiked with 0.01g/ml, 0.02g/ml, 0.25g/ml and 0.4g/ml of laboratory grade Oxytetracycline hydrochloride (OTC), Streptomycin sulphate (STREP) , Sulfamethazine (SMZ) and Sodium penicillin G (PEN G) respectively. The drug bearing milk was subjected to pasteurization (63oC for 30mins) and ultra high temperature treatment (121oC for 15 mins) to determine the effect of the heat treatment on antimicrobial activity of the various drug concentrations. Forty four(14.7%) of the milk samples tested were positive for residues, most of theresidues occurred in milk from Palladan and Graceland with 36.8% and 29.7% of the samples collected from these areas having residues while no residues were detected in Gabari, Hanwa and Unguwan Rimi. Residue occurrence was significantly (P<0.05) associated with location and recent history of antimicrobial use (within 4 weeks). Antimicrobial activity persisted up to the 10-7 dilution for OTC, STREP and PEN G while no activity was detected at dilution of 10-7 for SMZ in milk subjected to pasteurization. For the sterilised spiked milk, there was a reduction in antimicrobial residue of OTC at 10-6 and 10-7 dilutions while antimicrobial residue persisted up to 10-7 dilution for SMZ, STREP and PEN G. Consumers are predisposed to health hazards due to the presence of residues as a result of non observance of withdrawal period and gross misuse of antimicrobial residues. This emphasises the need for effective prevention of infectious diseases, use of viii alternatives to antibiotics, strict observation of antibiotic cessation times, creation of more awareness and establishment of a national antibiotic residue monitoring program in Nigeria

DETERMINATION OF ANTIMICROBIAL RESIDUES AND THE EFFECT OF HEAT TREATMENT ON RESIDUAL CONCENTRATION OF SOME ANTIMICROBIAL DRUGS IN FRESH COW MILK IN ZARIA, NIGERIA