Two toxicity outbreaks resulted from feeding of overgrown napier grass in cattle and buffaloes were investigated and the results were compared with experimental study conducted on 4 healthy buffalo calves after feeding the same fodder. Similar type of toxic symptoms viz. severe inappetance, straining, constipation, dryness of muzzle, dullness, dyspnoea with normal water intake and zero rumen motility were observed in experimentally toxicated as well as naturally affected animals. Similar type of biochemical and hematological alterations were also observed in both groups i.e. experimentally intoxicated and naturally affected. The animals were successfully treated and all altered biochemical and hematological parameters were returned to normal values within 5 days of treatment.