Effects of bacterial inoculants and an enzyme on the fermentation quality and aerobic stability of ensiled whole-crop sweet sorghum

A study was conducted to evaluate the effects of bacterial inoculation and cellulase on the fermentation quality of ensiled whole-crop sweet sorghum (WCSS, Sorghum bicolor L. Moench). The WCSS (323 g dry matter (DM)/kg, 251 g water soluble carbohydrates (WSC)/kg DM, 43 g crude protein (CP)/kg DM and 439 g neutral detergent fibre (NDF)/kg DM) was ensiled with i) no additive (control); ii) Lactobacillus buchneri (LB); iii) Lactobacillus plantarum (LP); and iv) LB+E, a combination of LB and enzyme. These treatments were ensiled in 1 L anaerobic jars for 25 days. The jars were opened on days 3, 7 and 15 to determine pH, while those of day 25 were sampled to determine nutrient composition, fermentation characteristics and aerobic stability. Inoculation reduced pH, butyric acid and ammonia-N and increased lactic acid content in sweet sorghum silage compared with the control. The aerobic stability of WCSS was improved with LB, while it was reduced with the homofermentative LP treatment compared with the control. The LB+E reduced the fibre, but increased residual WSC of silage. The aerobic stability of LB+E silage was lower than LB treated silage. Using enzymes to increase the WSC content of crops that already have high levels of WSC may result in reduced aerobic stability of silage. Further work is needed to evaluate these effects on silage produced on farm scale and on animal production performance.