Fermentation characteristics of different purposes sorghum silage

Sorghum stands out among other plants recommended for ensiling due to its forage composition, its resistance to drought, and its planting range. New cultivars of grain and sweet sorghum that can be used for silage production are available, but there is little information regarding their ensiling characteristics. The aim of this study was to evaluate the fermentation characteristics at the ensiling of different purpose sorghum cultivars, at two crop periods. The trial was carried out at the Plant Production Department of the Federal Institute of Education, Science and Technology of Rondonia, Colorado do Oeste campus, Rondonia, Brazil, and chemical analyses were performed at the Laboratory of Animal Nutrition, at the Federal University of Mato Grosso, Cuiaba campus, Mato Grosso, Brazil. The experimental design used was a randomized block, in split-plot design, with four replicates. The plot treatments consisted of six sorghum cultivars grown for different purposes (grain sorghum: BRS 308 and BRS 310; forage sorghum: BR 655 and BRS 610; sweet sorghum: BRS 506 and CMSXS 647). Split-plot treatments consisted of two cropping seasons (first crop and second crop). The grain sorghum cultivar BRS 310 was the only one that had suitable dry matter content for ensiling; however, it was also the only one that did not show ideal water soluble carbohydrate content for ensiling. Nevertheless, all treatments presented pH below than 4.2 and ammonia nitrogen lower than 12% of total N, which indicates that the fermentation inside the silo had proceeded well. For sweet sorghum cultivars, higher ethanol and butyric acid content were observed for the first crop than for the second crop. All evaluated sorghum cultivars can be used for silage production, but the use of sweet sorghum is recommended at the second crop.