Effects of light wilting and heterolactic inoculant on the formation of volatile organic compounds, fermentative losses and aerobic stability of oat silage

This study examined the effects of light wilting and applying a heterolactic inoculant on the formation of volatile organic compounds, fermentative losses and aerobic stability of oat silage. White oat (Avena sativa cv. URS Charrua) at heading stage was cut during the morning and allowed to wilt for 5 h or directly harvested in the afternoon. After mechanical chopping, forages were treated or not with Lactobacillus buchneri 40788 at 4 x 10(5) cfu/g. Treated forages were packed into 1.96 L gas-tight silos and stored for 112 d. Wilting was effective in increasing the dry matter (DM) content from approx. 200 to 300 g/kg and decreasing gas production during fermentation. Direct-cut favored the fermentation, resulting in higher lactic acid and lower pH in uninoculated silages. Silages treated with L. bucluieri had lower content of lactic acid, greater concentrations of acetic acid, ethanol and ethyl acetate, and substantially higher fermentative losses. Unwilted silage inoculated with L. buchneri had more 1-propanol, propionic acid and propyl acetate, perhaps due to the metabolism of epiphytic strains of Lactobacillus diolivorans. The heterolactic inoculant also led to higher content of NH3-N, 2,3-butanediol and 2-butanol in unwilted oat silage. Treating oat silage with L. buchneri delayed the increase in silage temperature upon air exposure; nonetheless, all silages presented high aerobic stability. Hence, inoculation with L. buchneri is not recommended for oat silages with DM concentrations up to 300 g/kg because it increases fermentative losses.