The objective of this screening study was to determine the in situ ruminal digestibility of dry matter (DMD), neutral detergent (NDFD), and acid detergent fiber (ADFD) of 4 corn stover-based experimental formulations of blended material as potential feedstuffs for dairy cows. Each prototype formulation included approximately 42.5% ground corn stover (CS), 15% distillers solubles and varied proportions of soybean meal (SBM) ranging from 33 to 40% to allow inclusion of CaO as a chemical treatment or a custom mixture of fatty acids. Treatments were 1) untreated corn stover (U-CS; 75%NDF, 44% ADF); 2) untreated pelleted blend (U-BLN; 46% NDF, 25% ADF); 3) CaO-treated blend (T-BLN; 44% NDF, 25% ADF); 4) blend with no fatty acid supplementation (NFA; 33% NDF, 23% ADF); and 5) fatty acid-supplemented blend (FA; 29% NDF, 18% ADF). Ten 5-g samples of each prototype and untreated CS were evenly assigned and incubated in the rumen of 2 ruminally-cannulated lactating Holstein cows for 48 h. Data were analyzed using the GLIMMIX procedure of SAS with prototype formulation and cow as fixed effects. By design, U-CS resulted in the lowest (P < 0.01) DMD, 37.3 ± 1.64% followed by T-BLN, which was 65.5 ± 1.64%. Prototypes NFA and FA were similar (P = 0.27) and averaged 78.5 ± 1.64% and U-BLN had the greatest (P < 0.01) DMD at 82.0 ± 1.64%. Untreated CS had the least (P < 0.01) NDFD at 29.8 ± 2.28% followed by T-BLN at 44.4 ± 2.28%, NFA and FA were similar (P = 0.63) and averaged 50.4 ± 2.28% whereas NDFD of U-BLN was 67.2 ± 2.28%. Digestibility of ADF was different (P < 0.01) across treatments, 25.2 and 38.2 ± 2.47% for U-CS and T-BLN, respectively; NFA and FA were similar (P = 0.10) averaging 45.6 ± 2.47% and U-BLN had the greatest (P < 0.01) ADFD at 59.6 ± 2.47%. Similarities between NFA and FA indicate that additional fatty acids did not alter digestibility. Although additional research is warranted to isolate the effects of chemical composition and mechanical processing, these results indicate that corn stover and SBM-based pellets are highly digestible and may be a suitable feedstuff for dairy cows.