Analyses of rumen fluid from "sudden death", lactic acidotic and healthy cattle fed high concentrate ration.

The sudden death syndrome (SDS) is a relatively new problem in the feedlot industry. With SDS, apparently healthy cattle in late finishing die suddenly with no sign of sickness or lesions indicative of other diseases. Rumen fluid pH, histamine, total lactate, L(+) lactate and volatile fatty acids (VFA) were compared among 19 SDS cattle, two animals with lactic acidosis produced through grain engorgement, and six healthy feedlot cattle maintained on a high energy finishing ration more than 100 days. Rumen fluid from the lactic acidotic cattle was high in lactic acid and histamine concentrations, l o w in pH, and low in total volatile fatty acid (VFA) concentration. The rumen fluid from feedlot steers used as controls had moderately high total VFA concentrations, narrow acetate-to-propionate ratios, low lactic acid concentrations, no histamine, and pH below 6. Concentrations of lactic acid, hista-