The objectives of this study were to improve the nutrient value of the fibre portion in grower phase diet for feedlot cattle using a fibrolytic enzyme and improve rumen health and gut performance in late finishing feedlot cattle by adding 60B CFU Saccharomyces cerevisiae to the diet. Hypotheses were tested using 54 steers in consecutive randomized block designs. There was no impact of adding fibrolytic enzymes during grower and early finisher phases on any animal performance traits; however, adding enzymes significantly improved digestibility of DM, CP and NEg within the diet. Feeding yeast in late finisher diet decreased DMI by 31% and improved feed conversion ratios, while maintaining similar ADG to cattle fed a control diet. This study has demonstrated that use of a fibrolytic enzyme in feedlot diets did not improve performance, while yeast addition to the late finishing diet significantly improved feed conversion through the decrease in DMI.