Physic nut (Jatropha curcas L.) is a multipurpose drought- resistant small industrial tree or shrub, widespread throughout the arid and semi-arid tropical and subtropical regions of the world whose toxicity is attributed to the antinutritional factors including trypsin inhibitor; lectin, phytate and phorbol esters in the seed and other parts of the plant which restrict its use as animal feed. In this study, the detoxification of Jatropha curcas kernel meal (JCKM) was carried out using selected organisms isolated from food products using solid state and submerged fermentations at two separate periods (five and ten days) to determine the proximate composition and toxicity in whistar rats for two weeks using standard laboratory methods. Increase in fermentation duration was found to produce significant increase (p<0.05) in protein, content at both day five (46.97±1.08mg/g) and day ten (49.96±1.32mg/g) when compared to the control (40.14±2.12mg/g) while crude fiber, fat and carbohydrate decreased with increase in fermentation time. The moisture content of J. curcas kernel fermented with submerged method (9.51±0.26mg/g) and solid state (6.86±0.71mg/g) were significantly higher (p<0.05) compared to the control (5.29±0.87mg/g). Detoxified (DTX) and non detoxified (NDTX) JCKM fed rats showed significant reduction (p<0.05) in neutrophil count when compared with the control (rats fed commercial feed). A significant increase (p<0.05) in lymphocyte level and non significant difference (p<0.05) in eosinophil count was observed in NDTXJCKM when compared with the control. There was no significant difference (p>0.05)in monocyte count between NDTX, DTX and control. Detoxification of JCKM did not affect the haematological indices (platelet, RBC, MCH, MCHC, MCV and PCV levels) of rats except for haemoglobin (Hb) level which showed significant reduction (p<0.05) when compared with the control. There was a significant increase (p<0.05) in the biomarkers of the hepatic function (AST and ALT level) in rats fed with NDTX JCKM except for ALP level which was significantly lower (p<0.05) when compared with the control. Although there was elevation in the total protein (TP) level in DTX JCKM but it was not significantly different (p>0.05) from the control. The results revealed that rats fed with DTX and NDTX JCKM had a significant  increase (p<0.05) in body weight than the control. The results obtained suggest that detoxified JCKM could be used to improve nutritional quality of animal feed.