Three experiments were conducted to determine effects of feeding alternative feeds or feed additives to cattle consuming feedlot diets on diet digestibility, rumen fermentation, growth performance, and carcass characteristics. In the first experiment, effects of adding a Saccharomyces cerevisiae product (SC) to cattle fed feedlot diets on diet digestibility and rumen fermentation were examined. Results of the first experiment suggest that feeding 1.0 g SC/hd daily may result in improved rumen acetate: propionate ratio. However, feeding 1.0 g SC/hd daily reduced rumen VFA concentrations, NH3-N concentration, and pH. In the second experiment, effects of partially replacing steam flaked corn with soy glycerin and distillers grains on diet digestibility and rumen fermentation in cattle were examined. Feeding distillers grains resulted in increased rumen propionate, rumen branched-chain VFA, and total rumen VFA. Feeding glycerin resulted in increased rumen pH and rumen propionate, and decreased rumen acetate. Feeding distillers grains or glycerin caused a reduction in rumen acetate: propionate ratio. In the third experiment, effects of replacing dry rolled corn with either 20% full-fat distillers grains, or 20% or 47% reduced-fat distillers grains (equal fat concentration as inclusion of 20% full-fat distillers grains) on feedlot cattle growth performance and carcass characteristics were examined. Results from this experiment indicated that utilizing reduced-fat distillers grains in place of full-fat distillers grains or dry rolled corn does not impact animal growth performance or carcass characteristics.