The aim of this study was to determine the Clinical observations (Visually and via Laboratory analysis) and haematological changes induced by subchronic administration of methanolic leaf extract of Crotalaria lachnosema (C. lachnosema) leaf (MLECL) on male Wistar rats. Four groups designated as Groups 1(control), 2, 3 and 4, of ten rats each, which were exposed to the extract in feed at dose levels of 0, 40, 200 and 1000 mg/kg for 42 days respectively. The clinical observations were recorded. At the end of the study period, the surviving rats were sacrificed following light ether anaesthesia and blood was collected from each rat via jugular venesection. The extract was found to cause impairment in both the body weight and relative organ weights of the exposed rats at termination of the experiment (P < 0.05) compared to the control group. The extract was found to affect the erythron only in group 2 with total red blood cell count (7.72 ± 0.25 × 1012/L), haemoglobin concentration (127.00 ± 2.66 g/L) and packed cell volume (48.44 ± 2.11 %) being significantly (P < 0.05 ) lower relative to those of the control (8.86 ± 0.32 × 1012/L, 150.80 ± 6.03 g/L and 48.44 ± 2.11 %, respectively). It was concluded from these studies that exposure to MLECL caused toxic effects in male Wistar rats (toxic effect like the decreased erythron; haematopoietic system is one of the most sensitive targets of toxic compounds, and thus considered an important index in pathophysiological status in man and animal). Human food or animal feed products contaminated with the plant C. lachnosema, even at very low concentrations, with the LD50 of 1300 mg/kg should be discouraged.
Key words: Crotalaria lachnosema, Haematology, LD50, Toxicity, Weight changes