ABSTRACT

Cassava leaf extract was prepared and used for acute toxicity test on the Fingerlings of Oreochromis niloticus. Five graded concentrations of 100%, 80%, 60%, 40% and 20% with replicates (representing tanks 1, 2, 3, 4, 5 and a control tank 6) were used. One hundred percent mortality was recorded in tanks I and 2, while 60% and 30% mortality were recorded in tanks 3 and 4 respectively after 96th hour. Later the percentage mortality increased in tanks 5 and 6 after 96 hours. Opecular beats increased from 44 beats in initial to 75 beats in 24 hours and decreased to 30 beats in 48 hours then resulted to a lethal condition; Water uptake decreased from 18 in initial to 6 in 48 hours then to a lethal condition. Also effects of the different concentrations of the crude cassava leaf extract on the haemoglobin (HB), Haematocrit (HT), Red Blood Cell Counts (RBCC), Mean Corpuscular volume (MCV), White Blood Cell Counts (WBCC), Mean Corpuscular Haemoglobin (MCH), Mean Corpuscular Haemoglobin Concentration (MCHC) were studied. The lower concentrations of 20% and 40% were not toxic as the higher concentrations of 60% 80% and 100% respectively. The changes observed in all the concentrations were significant (P<O.05). The HB, Ht and RBCC increased significantly (P<O.05), while the calculated values of MCH, MCV, MCHC and WBCC decreased throughout the various concentrations. The median lethal concentration (96-hr LC50) value was 19.953mg, while the threshold value (safe level) was 44.668mg. The results have been interpreted in the light of existing data on the haematological responses of Oreochromis niloticus exposed to crude cassava leaf extract.