Effects of microbial inoculation on dry matter losses, fermentation profile, and aerobic stability of wet brewers grain stored with increasing concentrations of dry ground corn

Abstract

The objective of this study was to evaluate the effects of microbial inoculation and storage length on the fermentation profile, dry matter losses and aerobic stability of wet brewers grains (WBG) ensiled with increasing amounts of dry ground corn (DGC). Pure WBG (210 g/kg of dry matter [DM]) and 3 mixtures of WBG and DGC were prepared targeting for a dry matter content of 350 g/kg (RC35), 500 g/kg (RC50) or 650 g/kg (RC65). Distilled water (CON) or one of two microbial inoculants were applied, a combination with Pediococcus pentosaceus at 1 × 105 cfu/g of fresh forage and Propionibacterium freudenreichii at 2 × 104 cfu/g of fresh forage (PPPF), or a heterofermentative with Lactobacillus buchneri at 7.5 × 105 cfu/g of fresh forage and Pediococcus pentosaceus at 1 × 105 cfu/g of fresh forage (LBPP). Mixtures were ensiled in laboratory silos in quadruplicate and opened at two storage lengths (SL), 30 or 60 days (30 d and 60 d, respectively). Data were analyzed as a completely randomized design with a 4 × 3 × 2 factorial arrangement of treatments using Proc Glimmix of SAS. Butyric acid concentration decreased (P < 0.04) with addition DGC regardless of microbial inoculation. Mixtures with greater amounts of DGC (RC50 and RC60) reduced (P < 0.01) DM losses and pH, regardless of inoculation or storage length. Lactic acid concentration was greater (P ≤ 0.05) with intermediate addition of corn (RC35 and RC50). Acetic acid concentration did not differ among inoculation treatments when corn was added to the mixtures; however, LBPP increased 1,2-propanediol in RC50 and RC60. Moreover, LBPP increased aerobic stability only for the RC65 mixture. In conclusion, the addition of DGC to WBG improves fermentation and decreases DM losses, while inoculation with LBPP can improve aerobic stability in RC65. Our data suggests that adding DGC to WBG is a feasible strategy to store WBG for up to 60 days and inoculation with PPPF and LBPP can improve further the conditions of the WBG and DGC mixtures silage.