To test efficacy of additives to reduce SARA, a protocol was developed to model SARA conditions using an in vitro continuous culture fermentor system at the Rumen Fermentation Profiling Laboratory, West Virginia University. A BASE diet was formulated with a 60:40 forage:concentrate (F:C) ratio (DM basis). Inclusion of corn silage, alfalfa balage, grass hay, ground corn (GC), SBM, corn gluten meal, corn gluten feed, soybean hulls, dried molasses, sodium bicarbonate and a mineral-vitamin supplement were, respectively, 36.1, 12.1, 12.1, 11.00, 13.7, 1.0, 1.0, 8.3, 2.0, 2.0 and 1.8% of DM. Mean particle size of GC was 870 µm (SD = 2.7). In Trial 1, diet SARA1 was formulated by reducing the BASE diet F:C ratio to 52:48. Corn was increased to 20.9% with 50% (DM basis) of the GC replaced with steam flaked corn (SFC). Treatments were: BASE diet fed as 25-g meals 4 times daily for 10 d (B) and BASE diet fed as 25-g meals 4 times daily for 7 d followed by the SARA1 diet fed as 50-g meals 2 times daily for 3 d (S1). Treatments were replicated in triplicate. Data collected the last 3 d included pH at 30-min intervals and NDF digestibility. Daily average pH were calculated for each fermentor. All data were analyzed using PROC MIXED of SAS. Average and minimum pH were analyzed with a repeated-measures model. Fermentor was treated as a random variable and AR(1) was selected as the appropriate covariance structure. Average pH of S1 (6.25) vs B (6.28) was similar (P = 0.15). Minimum pH of S1 (6.06) vs B (6.15) tended to be less (P = 0.08). NDF digestion was less (P < 0.01) for S1 (41.5%) vs B (46.6%). In Trial 2, treatment S1 was replaced with S2 by altering the SARA1 diet to create SARA2 as follows: corn replaced sodium bicarbonate and the GC:SFC ratio changed to 1:2. Trial 2 protocol was similar to Trial 1. Average pH of S2 (6.17) was less (P < 0.05) than B (6.30). Minimum pH of S2 (5.88) was less (P < 0.01) than B (6.18). NDF digestion was less (P < 0.01) for S2 (30.5%) vs B (40.4%). It was concluded that using the tested protocol with diets BASE and SARA2 provided an appropriate SARA model.