Effects of chop-length and a ferulic acid esterase-producing inoculant on fermentation and aerobic stability of barley silage, and growth performance of finishing feedlot steers

The present study investigated the impact of forage chop length and a ferulic acid esterase producing (FAE) inoculant on fermentation, aerobic stability and the physically effective fibre value of barley silage for finishing feedlot cattle. Whole-crop barley (Hordeum vulgare L.; 310gDM/kg) was chopped to either a short (10.0mm; SC) or long (20.0mm; LC) chop length and ensiled with or without a FAE inoculant containing Lactobacillus buchneri LN4017, Lactobacillus plantarum LP7109 and Lactobacillus casei LC3200 in Ag-Bags® or mini silos. Data were analyzed as a 2×2 factorial using the MIXED procedure of SAS. In mini silos, the terminal pH of inoculated silage was lower (P=0.001) for SC than LC silage (3.87 vs 4.02). In mini silos, inoculation failed to increase acetic acid concentration of SC silage, but it increased acetic acid content of LC silage (P=0.034) and of both SC (45.7 vs 24.3gDM/kg) and LC (54.3 vs 15.9g DM/kg) in Ag-Bags®. In mini silos, lactic acid concentration was greater (P=0.011) in LC than SC (81.5 vs 67.3gDM/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 chop length, inoculation nor their interaction affected (P≥0.186) silage DM loss. Both inoculated and uninoculated SC silage remained stable over 8d of aerobic exposure, but inoculation prolonged the aerobic stability of LC silage by 5d (d3–8). Growth performance and DM intake of finishing steers were not affected (P≥0.257) by chop length, inoculation or their interaction, 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 the chop length of barley silage increased its physically effective fibre content, and the inoculant improved the aerobic stability of LC silage. However, likely owing to the low proportion of silage in the diet (100g/kg, DM basis), neither chop length nor inoculation altered the growth performance of finishing feedlot cattle.