Growing concern over the use of antibiotics and other growth stimulation in the animal feed industry has increased interest in evaluating the effects of Direct-fed Microbial (DFM) on animal performance (Sullivan and Martin, 1999). Some bacterial direct-fed microbials also seem able to function in the rumen. Depending on the species or combination of species, they can increase digestibility. Modes of action are variable and include native rumen microbiota enhancement through increased substrate breakdown, enhancement of nutrient uptake, stabilising rumen pH and provision of growth factors. The objectives of this study were to evaluate the effects of DFM supplementation on total tract digestibility.