Change Detection in Rumen Fermentation Characteristics and Ruminal Methane Gas Emissions Caused by Substituting Steam-Flaked Corn With Steam-Flaked Wheat Grains in Beef Finishing Diets in Laboratory Conditions

The main objective of the current study was to assess the associative impacts of substituting steam-flaked corn (SFC) with steam-flaked wheat (SFW) in beef cattle diets on in vitro rumen fermentation profiles, in vitro dry matter disappearance rate (IVDMD), and greenhouse gas (GHG) emissions, when dietary total mixed ration (TMR) diets were suspended with rumen fluid. Rumen fluid was collected from the three donor steers 2 h after feeding. Adding 0%, 10%, 20%, 40%, and 60% levels of the replacement of SFC with SFW grains dramatically increased the GHG emissions and ruminal pH (p < 0.05). Simultaneously, when SFW supplementation increased, IVDMD decreased (linear p < 0.05). Interestingly, in the presence of SFW, ruminal acetate, isobutyrate, and isovalerate increased linearly (p < 0.05), whereas valerate, butanol (quadratic, p < 0.01), phenol, and ethanol productions decreased (p < 0.01) with increasing SFW. The rumen's IVDMD and a molar proportion of acetate (R² = 0.62; p < 0.01) were significantly related to ruminal CH₄ production. The study's key findings indicated that partial replacement of ground SFW with SFC could not be effective in mitigating GHG emissions by altering rumen fermentation profiles compared to SFC.