Evaluation of Sweet Sorghum Variety for Biofuel Feedstock and Animal Feed.

Sweet sorghum is a valuable biofuel feedstock with cultural benefits from its high sugar content juice and high biomass. A field study was conducted in the southeast Louisiana with four varieties: Dale, M81E, Topper, and Theis to investigate total biomass yield, juice production, juice quality and bagasse nutritive value. Total biomass of early dough stage sweet sorghum averaged 56 ton per ha and sugar content in the juice reached 15.3o Brix. Sugar content in juice was highest in Dale and lowest in Theis. Juice in Dale contains 1.28 g/l (w/v) of fermentable sugars which produce 0.65 g/l (w/v) of ethanol by fermentation. Other components such as bagasse and leaves were degradable into simple sugars after enzymatic saccharification and were able to produce ethanol. The yield of glucose from lime treated bagasse (6%, w/w) by enzymatic saccharification was 30.0 g/l (w/v) and the ethanol recovery from the bagasse was 14.5 g/l (w/v). In vitro true digestibility of bagasse was 681, 590, 589, and 549 g kg DM-1 in Dale, Topper, ME81-E, and Theis, respectively. This study demonstrated sweet sorghum cultural values as biofuel feedstock and as livestock feed.