Laboratory scale experiments were conducted consisting of silages of chopped sweet sorghum, sweet sorghum bagasse, combinations of sweet sorghum with maize stalks, treated and untreated with LAB inoculant and ethanol as preservation additives. Twelve types of silages were obtained by combination of types of biomass and additives. The effect of these additives and biomass combinations on the qualities and composition of the resulted silage was examined. Silages were analyzed to assess the preservation of nutritive value and quality of the ensiled biomass. The lowest pH values (3.3) where in silages of sorghum bagasse and sorghum bagasse with ethanol. The highest pH values (6-6.3) where in silages of maize stalks, where the highest number of contaminants where found as well. Soluble sugars where preserved in high concentration in ensiled biomass treated with ethanol: over 91% of the water soluble sugars was found in sorghum ensiled with ethanol, and less than 57% in sorghum ensiled with lactic bacteria. The ethanol additive inhibited as well the breakdown of silage protein and the multiplication of contaminants (1.9 log 10 cfu g -1 in ethanol treated sorghum comparing with 3.2 log 10 cfu g -1 in control sorghum silage without additives). Preservation parameters of maize stalks are improved by adding fresh sweet sorghum to dry maize stalks. Lactic bacteria inoculants ameliorate the preservation parameters in sweet sorghum and mixed biomass, but leads to consumption of sugars. Using ethanol as silage additive the biomass is well preserved, the growth of contaminants, soluble sugars and protein losses are inhibited. The loss in dry matter, crud fats, crude cellulose was not significant in all silages. A small portion of ethanol produced by fermenting sugar from sweet sorghum can be used to preserve the feedstock biomass. Sweet sorghum can be used as well to improve preservation qualities of corn stalks to be used as biogas feedstock.

sweet sorghum, silage, ethanol, inoculant.

Presentation: oral