A subacute experiment was undertaken for 14 days. The results obtained from these studies suggest that: 1) unless a highly Jimson weed seed contaminated feed is ingested (greater than 0.09% of body weight) or force fed, death should be a rare consequence of Jimson weed seed contamination; 2) Jimson weed seed toxicity in cattle as a result of feed contamination appears a self-limiting problem (rumen atony and anorexia prevent further intoxication until the blood levels of alkaloids are reduced to allow normal ruminant intestinal function); 3) cattle may exhibit signs of atropine toxicity at contamination levels of 881 seed/kg of feed or higher; 4) rumen fluid from heifers fed diet containing 4,408 Jimson weed seed had the greatest VFA concentration change from day 0 to 7; 5) in vitro fermentation of diets resulted in no difference in IVDMD values, but VFA concentration values tended to increase with increased concentrations of Jimson weed seed in the diet.