Feedlot performance and mass balance were evaluated on steers fed either 5% untreated corn stover (CON), 20% untreated corn stover (NONTRT), or 20% calcium oxide (CaO) treated corn stover (TRT) when fed with or without saponins (Micro-Aid) in a 3x2 factorial. In both WINTER and SUMMER experiments, ADG, F:G and HCW were improved (P \u3c 0.01) in CON and TRT fed steers compared to NONTRT fed steers. Micro-Aid fed steers had slightly greater ADG and DMI in the SUMMER. Manure% nitrogen (N) was greatest when NONTRT and TRT were fed compared to steers on CON diet. However, neither diet nor Micro-Aid influenced manure N amounts or N losses across both seasons
