Influence of inoculating forage with lactic acid bacterial strains that produce ferulate esterase on ensilage and ruminal degradation of fiber

By releasing ferulic acid from cell wall arabinoxylans, ferulate esterase (FE) can increase susceptibility of plant cell walls to enzymatic hydrolysis. As some lactic acid bacteria (LAB) produce FE, we investigated effects of ensiling perennial ryegrass (PRG) with LAB that produce FE on ruminal NDF degradation (NDFD) of the resulting silages. Among the 10,000 LAB screened, approximately 500 produced FE and 8 (i.e., Lactobacillus buchneri PTA-6138 and NRRL B-30866; Lactobacillus crispatus NRRL B-30868, 30869 and 30870; Lactobacillus reuteri NRRL B-30867; Lactobacillus brevis NRRL B-30865 and an unidentified Lactobacillus NRRLB-30871) were studied in detail. The PRG was harvested and ensiled with or without (control) inoculation with each individual LAB, in triplicate laboratory silos for 30 days. Silages were analyzed for fermentation characteristics, dried, ground (6 mm) and incubated in situ in Dacron bags (50 mu m pore size) for 48 h in the rumens of three ruminally cannulated steers adapted to a diet of grass silage. L. buchneri strains increased silage pH and acetate (P<0.05) and reduced lactate concentrations (P<0.05). With the exception of NRRLB-3087 1, all LAB increased (P<0.05) NDFD by 9-11%. To examine effects of combining L. buchneri PTA-6138 with Lactobacillus paracasei tolerans PTA-6135 (X11C38) on NDFD of whole plant corn silage (WPCS), forage (DM, 337 g/kg) was harvested and ensiled with or without inoculation in two silos of 2 tonnes each and allowed to ferment for 180 days. Fresh silage from each silo was fed to three ruminally cannulated steers in a cross-over experiment with two periods of 14 days that included 10 days for adaptation. WPCS was incubated in situ, as described above, in all six steers in a split-plot experiment with diet as the main plot and inoculation of silage as the subplot. Feeding inoculated silage did not influence NDFD and there was no interaction between the silage fed and inoculation of the silage incubated in situ. However, inoculation of forage with X11C38 increased NDFD by 15.8% (P=0.019). Since L. buchneri can improve aerobic stability (AS) of silage, we also determined effects of X11C38 on AS of WPCS. Forage from four hybrids was harvested, and each ensiled with or without inoculation in lour laboratory silos that were stored for 50-57 days. AS was determined by recording silage temperature with oxygen exposure in a thermostable environment. Inoculation with X11C38 extended the duration of AS for all hybrids by 42-105 h (P<0.05). Inoculation with LAB that produce FE improve NDFD in ensiled PRG and X11C38 extended AS and improved NDFD of WPCS, suggesting that higher NDFD was due to changes in forage during storage. (C) 2007 Elsevier B.V. All rights reserved.