The present study investigated the impact of forage chop length and a ferulic acid esteraseproducing (FAE) inoculant on fermentation, aerobic stability and the physically effectivefibre value of barley silage for finishing feedlot cattle. Whole-crop barley (Hordeum vul-gare L.; 310 g DM/kg) was chopped to either a short (10.0 mm; SC) or long (20.0 mm; LC)chop length and ensiled with or without a FAE inoculant containing Lactobacillus buchneriLN4017, Lactobacillus plantarum LP7109 and Lactobacillus casei LC3200 in Ag-Bags®or minisilos. Data were analyzed as a 2 × 2 factorial using the MIXED procedure of SAS. In minisilos, the terminal pH of inoculated silage was lower (P=0.001) for SC than LC silage (3.87 vs4.02). In mini silos, inoculation failed to increase acetic acid concentration of SC silage, butit increased acetic acid content of LC silage (P=0.034) and of both SC (45.7 vs 24.3 g DM/kg)and LC (54.3 vs 15.9 g DM/kg) in Ag-Bags®. In mini silos, lactic acid concentration wasgreater (P=0.011) in LC than SC (81.5 vs 67.3 g DM/kg) and inoculation decreased (P=0.020)the lactic:acetic acid in LC, but not SC silage. Populations of lactic acid bacteria were greater(P=0.002) and yeast lower (P=0.030) for inoculated silages stored in mini silos. Neither choplength, inoculation nor their interaction affected (P≥0.186) silage DM loss. Both inoculatedand uninoculated SC silage remained stable over 8 d of aerobic exposure, but inoculationprolonged the aerobic stability of LC silage by 5 d (d 3–8). Growth performance and DMintake of finishing steers were not affected (P≥0.257) by chop length, inoculation or theirinteraction, but the proportion of saleable meat and the rib eye area of carcasses was greater(P=0.017; P=0.035 respectively) for steers fed SC than for those fed LC silage. Increasing thechop length of barley silage increased its physically effective fibre content, and the inocu-lant improved the aerobic stability of LC silage. However, likely owing to the low proportionof silage in the diet (100 g/kg, DM basis), neither chop length nor inoculation altered thegrowth performance of finishing feedlot cattle.