Reduction of fermentation losses in sweet sorghum silages using cornmeal

Some experiments in livestock production demonstrated that silage made from sweet sorghum produces excesses of effluent. In this sense, the aim of this study was to evaluate if the inclusion of ground corn in sweet sorghum silages could improve the fermentation process to reduce effluent. The silages were prepared and all chemical analyses were performed on the experimental farm and the forage lab based in the Department of Animal Science, College of Agricultural Sciences. For both sorghum cultivars (BRS 506 and BRS 511), ground corn was added as a treatment at a level of 15% of the dry matter content (DM) used alongside a control where ground corn was absent. Analysis was carried out with a completely randomised design (2x2) based on four repetitions per treatment, using a Tukey test (5% level of significance). The experiment was developed using mini-silos made of PVC (diameter of 10 cm and 50 cm tall) sealed at the bottom end with a cap. At the bottom of the silos, dry sand was placed under a sheet and a cotton fabric in order to separate forage and quantify the effluent. Harvesting occurred when each cultivar reached 28% DM (when the grains achieved a dough stage). Inclusion and mixture of ground corn to the chopped material was done manually and compaction was performed using wooden bats. After compaction, the silos were sealed with a plastic sheet using a duct tape, weighed and stored during 100 days. The variables under observation were: dry matter losses (DML), gas losses (GL), effluent production (EP) and pH measured according to Jobim et al. (2007). Silage pH was unaffected (P>0.05) by treatments (overall mean 3.7). Silages prepared with cultivar BRS 506 presented greater EP (P<0.05) (60 litres per ton of silage) compared to cultivar BRS 511 (40 litres per ton of silage). Ground corn reduced (P<0.05) EP by 43.5% and 45.6% in BRS 506 and BRS 511 silages, respectively. The treatment with 15% ground corn reduced DML (28.6%) and GL (26.7%) (P<0.05). Regarding total dry matter, silages prepared with cultivar BRS 511 showed the lowest DML (7.5%) and GL (3.8%) (P<0.05). The cultivar BRS 511 showed the best results regarding fermentation losses and the inclusion of 15% of ground corn reduced DML, GL and EP.