Effects of an inoculant containing a Lactobacillus buchneri thatproduces ferulate-esterase on fermentation products, aerobicstability, and fibre digestibility of maize silage harvested atdifferent stages of maturity

The aim of this research was to study the effects of a commercial inoculant containingLactobacillus casei and Lactobacillus buchneri that produces ferulate esterase enzymes onfermentation products, aerobic stability, microbial status, dry matter (DM) losses, anddigestibility of neutral detergent fibre (aNDF-D) of maize silages ensiled at four stages ofmaturity. The kernel milk line (ML) was used to time the forage harvest, and 1/6 ML, 2/5ML, 3/4 ML and black layer (BL) were observed, for harvest stages I, II, III and IV, respec-tively. Chopped whole plant maize was untreated or treated with L. casei LC32909 and L.buchneri LN40177, which were applied to achieve a final application rate of 1 × 104cfu/gand 1.0 × 105cfu/g of fresh forage, respectively. The maize was ensiled in laboratory silosfor 260 days before opening. The DM content, starch and ether extract concentrations andmould count increased, whereas water activity, nitrate, ash, water soluble carbohydrates(WSC) and crude protein (CP) contents progressively decreased with increasing maturity atharvest. The 24-h and 48-h aNDF-D were similar for harvest stages I, II and III, whereas theywere the lowest in harvest stage IV. The effect of inoculation decreased with increasing DMcontent at ensiling, and the inoculum was ineffective at the last stage of maturity, probablydue to the high epiphytic lactic acid bacteria (LAB) count, low water activity and low sugarcontent that could have negatively influenced the inoculation outcome. The inoculationlowered the lactic acid, yeast and mould counts and increased acetic acid, 1,2-propanediol,pH, DM losses and aerobic stability in the first three harvest stages, whereas no differenceswere observed between the treated and untreated silages harvested at the last stage ofmaturity. Regardless of the treatment, the yeast count fell under the detection limit andAbbreviationsthe aerobic stability of the silage increased to over 200 h when the acetic acid contentexceeded 25 g/kg DM. Furthermore, the DM losses were closely correlated to the acetic acidproduction and increased to 80 g/kg of DM in the treated silages harvested at the earlieststage of maturity. The potential milk production, estimated with MILK2006 model (Shaveret al., 2006, http://www.uwex.edu/ces/dairynutrition/spreadsheets.cfm), showed that thegreater aNDF-D of the treated silage, which was observed in harvest stages I and III, did notcounterbalance the higher DM losses attributable to the L. buchneri activity during ensiling,in terms of milk per Mg of original ensiled DM.