ABSTRACT
The present study was conducted to investigate the toxicological effect and the fate of the insecticide chlorpyrifos in laying hens. Chlorpyrifos and some of its degradation products have been prepared in our laboratory for the present investigation. Hens, were fed 40 ppm of chlorpyrifos in the feed for two months followed by one month recovery period. After 30 days of the experiment, both plasma and red blood cells-cholinesterase activity showed a moderate inhibition amounting to 32.4 and 17.9%, respectively. Liver and kidney functions as well as lipid profile of the treated hens were significantly increased during the experiment periods. All the blood parameters returned to the control values after one month recovery period except liver enzymes [ALT, AST and alkaline phosphatase]. The residual analysis of the extracts of both eggs and different organs of laying hens revealed that, there was a considerable amount of the parent compound which amounted to: eggs [0.02 ppm], fat [0.095 ppm], liver [0.093 ppm] and muscles [0.007 ppm] at the end the experiment. Chromatographic analysis by TLC and HPLC showed the presence of four degradation products in addition to the parent compound chlorpyrifos