To examine the effects of acute exposure to fumonisin-containing culture material (FCCM), 15 crossbred wether lambs were dosed intraruminally with FCCM containing 0 (CONTROL, n = 3), 11.1 (LOW, n = 4), 22.2 (MED, n = 4), or 45.5 (HIGH, n = 4) mg of total fumonisins (B1, B2, and B3)/kg BW daily for 4 d. Blood samples were collected daily, and on d 11 lambs were killed and necropsied. Changes in serum constituents in fumonisin-treated lambs indicative of liver damage, included increased (P < .05) activities of alkaline phosphatase, gamma-glutamyl transferase, aspartate aminotransferase, and lactate dehydrogenase. Serum concentrations of cholesterol, triglycerides, urea nitrogen, and creatinine were also increased (P < .05) in lambs dosed with FCCM. Hemoglobin tended to increase (P = .07) and white blood cell count tended to decrease (P = .08) in HIGH lambs and activated partial thromboplastin time tended to decrease (P < .10) in lambs dosed with LOW and MED treatments. Mitogen-induced lymphocyte blastogenesis was not different (P = .14) among treatments. Feed intake markedly decreased (P < .01) following the first dosing of FCCM and continued to decline throughout the study. Ruminal VFA concentrations and pH tended to decrease (P < .10) at d 11 in treated lambs. Relative liver and kidney weights (g/100 g of BW) increased (P < .05) in fumonisin-treated lambs. Histiolgical examination revealved tubular nephrosis and mild hepatopathy in dosed lambs. Lambs receiving the HIGH treatment died on d 3, 4, 5, and 7 of the study and on d 9 one lamb on the MED treatment died.(ABSTRACT TRUNCATED AT 250 WORDS)