A Ibrahim, A Junaidu, M Garba
antibiotics, cattle, meat, residues, slaughter, sokoto
A Ibrahim, A Junaidu, M Garba. Multiple antibiotic residues in meat from slaughtered cattle in Nigeria. The Internet Journal of Veterinary Medicine. 2009 Volume 8 Number 1.
Drug residues in animal derived products are of public health and economic importance. A microbial inhibition test using
The primary purpose of veterinary drugs, biologics and pesticide chemicals is to safeguard the health and welfare of animals4. Antibiotics used for these purposes can occur as residues for some time in these animals before they are excreted. A chemical
Materials and Methods
The study was conducted in Sokoto, northwestern part of Nigeria. With a land area of 28, 232, 37 sq kilometer, Sokoto state is located between longitude 110 30” to 130 50” east and latitude 40 to 60 north. It is bordered in the north by the Niger republic, Zamfara state to the east and Kebbi state to the south and east. Agriculture is the major means of livelihood.
Fifty slaughtered cattle were randomly selected over a period of four weeks, from 23rd June to 18th July 2008. Samples transported in an ice pack to the Veterinary Public Health Laboratory of Faculty of Veterinary Medicine, Usmanu Danfodiyo University Sokoto. A total of 100 samples (50 liver and 50 kidneys) were screened for antibiotic residues.
Preparation of inoculums and media
Pure cultures of
The European Four Plate Test as described by Oboegbulem and Fedelis (1996) was employed. A piece of meat (1x2.5mm) was applied to four plates of agar media, three of which were inoculated with
Test bacterium has known susceptibility to antibiotics. Presumptively, positive result at pH6 indicates the presence of tetracycline antibiotics, streptomycines at pH7 and penicillines at pH8. These antibiotics readily diffuse at the respective pH inhibiting bacterial growth around zone of meat. At significantly high concentration (
The European FPT is essentially a multiresidue technique for screening animal products. Despite limitations, the use of bacteria in detecting residues has since been useful in the meat industry 3, 13.
*Maximum residue limit (
Table 1 shows a total of 22(44%) slaughtered cattle positive for the presence of antibacterial substances. Out of these, the liver of 16(32%) slaughtered cattle was found positive while, both liver and kidneys of 6(12%) slaughtered cattle tested positive. However, base on the pH to which meat sample was found positive, presumptively, penicillin (14%) is the leading antibiotic followed by tetracycline (8%) and streptomycin (4%) in samples positive on a single plate. For samples with the multiple antibiotic residues: 8% contain tetracycline, streptomycin and penicillin, 4% tetracycline and streptomycin, 1% tetracycline and penicillin and, 4% penicillin and streptomycin.
The issue of veterinary drug residues in animal derived food has become increasingly important in many developing countries 4. The presence of antibiotic residues in liver and kidney is similar to other findings in Nigeria 5, 6, 7, 9, 12. However, these researches detected single antibiotic. The result of this study indicates the presence of multiple antibiotic residues and that penicillin, tetracycline and streptomycin in order frequency are commonly use or misuse drugs in cattle in Sokoto. Antibiotic residues were found more in the liver (44%) than in the kidney (12%). This could suggest that most samples were taken at the time when drugs were been metabolised in the liver not yet at the stage of clearance by the kidney. Invariably, antibiotics are most often administered close to the time of slaughter. The result also shows higher rate (44%) of antimicrobials than previous works done by Oboegbulem and Fedelis (1996), Kabir
The zone of inhibition found between two pieces of liver on one of the plates could be due to synergism (from synergistic drugs e.g penicillin and streptomycin) or probably a reflection of high concentration of single inhibitory substance. Synergism occurs when the pharmacologic effect of interaction between two drugs exceeds additive effect of concurrent administration 11.
The presence of antibiotic residues in meat is a serious problem that is yet to be addressed in developing countries like Nigeria where safety of food regarding drug residue is highly questionable. The multi antibiotic residues detected in meat from slaughtered cattle intended for sale to the human populace in Sokoto could be attributed to irrational use of drugs in food animals consequent to lack of regulatory system for veterinary drug use and control as observed previously1. In addition stakeholders involved do not adhere to withdrawal period. Non adherence to withdrawal periods is the major cause of chemical residues14. To date there have been only few studies to determine the lowest dose of antibiotic required to perturb the normal human flora 15. It is therefore safer to consider any amount of drug residue significant. This necessitates that all effort including awareness creation, observance of withdrawal period, effective surveillance, monitoring and control on the use of veterinary drugs to prevent drug residues in animal derived products be employed.
The authors wish to acknowledge Prof. S.I Oboegbulem and Dr. Sati Samuel (NVRI Vom) for their assistance in sourcing the test bacteria. Dr A. A. Magaji, Dr. A.T Elsa and Dr. M.D Salihu were highly supportive. We are so grateful to Mal. Lawal Usman (Microbiology Unit, UDUTH) and Mal Nata’ala (School of Med. Lab Sci, UDUS) for assisting in the laboratory work.