AFlatoxin residues in edible tissue of poultry in Zambia
Nalube, Sidney Muntanga
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The aflatoxins, toxins produced by the fungus Aspergillus flavus, have been detected in both imported as well as locally grown maize in Zambia.The problem of toxicity caused by the ingestion of aflatoxin-contaminated maize was approached by determining the levels of residues in edible tissue of poultry from known dietary levels of aflatoxin in maize. The livers and spleens, gizzards and hearts, and thighs were chosen for aflatoxin residue analysis. This study was conducted to determine the aflatoxin residue levels in tissues of village chickens that had been fed diets containing total aflatoxin concentration of 4750mg/kg of feed (equivalent to aflatoxin Bl concentration of 1650 mg/kg) at 0% (for controls) 25% (for low AF diet) and 75% (for high AF diets) inclusion levels for 21 days. Residues of aflatoxin were determined by thin layer chromatography. Results show that aflatoxins Bl, B2,Gl, G2 and Ml were deposited in all tissues analysed. The highest levels were present in the livers and spleens (8.0 mg/kg, low AF diet; 15.4 mg/kg, high AF diet) and the lowest were in the thighs (1.6 mg/kg, low AF diet; 9.4 mg/kg,high AF diet) . At the end of the experiment, the livers were observed to be pale, enlarged and friable.Since only a small fraction (less than 1%) of the highest level of aflatoxin tested and ingested was deposited in the tissues, either as the original compound or as its metabolite, there appears to be little danger of carry-over of dietary aflatoxin to poultry tissue. The toxic levels (i.e. levels that can cause death) to humans is considered to be approximately 1.7 mg/kg daily (Campbell and Stoloff, 1974), which means that the amount the poultry would need to consume to reach this tissue level would cause pathological symptoms or even death. Therefore the chance of these contaminated birds entering the food chain can be considered to be minimal since people traditionally do not eat poultry dying of unknown cause.
- Natural Sciences