It is more accurate to think of bacteria as beef cattle's main feed. The bacteria thrives on the grass a cow munches down, then, through an array of stomachs, the cow digests a portion of this bacteria-in-residence for its nutrient needs. If all the beast has to eat is grain, it will have a very disrupted flora in its gut. A cow cannot - CAN NOT - reach and maintain optimal health unless it eats its natural food: grass. Grain-fed beef is denatured beef. Foodies would, in turn, enjoy better health if they included such biological imperatives in their criteria of what constitutes a truly special meal.