Holo-analytical models are used for the prediction of nutritional responses, product comparisons and the setting of future research priorities. Following holo-analyses of the efficacy of exogenous enzymes in monogastrics (Rosen, 2006), this study in ruminants comprises holo-analyses of all available data from beef and dairy cattle, negatively-controlled, start-to-finish tests in meat and milk production. The beef enzymes mainly contain amylases, cellulases and xylanases, with a total of eight other side activities and the dairy, betaglucanases, cellulases and xylanases, with 12 declared side activities.