The objectives of this study was to assess in vitro (IV) potential abatement of CH₄ production rate of 4 commercially available products [ionophore (I), bambermycin (B), saponin (S), and condensed tannin (CT)] when fed in combination with dried distillers grain (DDG) on growing feedlot type diets. The IV gas production technique was used to determine the fermentability of 3 base diets with 3 levels of DDG (0, 20, and 40% DM). Diets contained alfalfa hay, ground corn, and Bermudagrass hay. The 15 diets (DDG0, DDG20, DDG40, I0, I20, I40, B0, B20, B40, S0, S20, S40, CT0, CT20, and CT40) were incubated in duplicates, 6 times each (15 × 2 x 6 × 2; n = 360 bottles), and the alfalfa hay was incubated alone in each run as standard. Blanks (n = 2 bottles/incubation time), containing rumen fluid and medium only, were used to adjust the CH₄ production. Methane was computed as adjusted CH₄ concentration divided by the amounts of NDF (CH₄NDF, mM/g NDF), NFC (CH₄NFC, mM/g NFC), fermentable carbohydrate (FCHO = sugar + starch + available NDF) (CH₄FCHO, mM/g FCHO), OM (OM = 100 – Ash) (CH₄OM, mM/g OM), and fermentable OM (FOM = OM – Ash) (CH₄FOM, mM/g FOM). . The PROC MIXED of SAS (SAS Inst., Cary, NC) was used to analyze the CH₄ data assuming a completed randomized design. Diets, products, and products within levels were assumed to be fixed factors and replicate within diet to be random. The convergence method was REML. Products affected CH₄ production for total concentration (P = 0.0003), Adj CH₄ (P < 0.0001), CH₄NDF (P < 0.0001), CH₄NFC (P < 0.0001), CH₄FCHO (P < 0.0001), CH₄FOM (P < 0.0001), and CH₄OM (P < 0.0001). Ionophores had the greatest effect (P > 0.05) among all tested products to further decrease CH₄ production, being the only significantly different from the DDG control diets. Levels (0, 20 and 40% DM) of DDG were not significant (P > 0.2076) in decreasing CH₄ production. This is probably because the fat content in the diets were not high enough. Previous IV data from our laboratory had shown that responses in CH₄ mitigation due to fat content in the diet was only significant when DDG levels were over 50% or 7.3% EE in the diet. These IV results suggested that ionophores have the potential to further decrease methane production from ruminants fed DDG based diet.