Effects of ensiling forage soybean (Glycine max (L.) Merr.) with or without bacterial inoculants on the fermentation characteristics, aerobic stability and nutrient digestion of the silage by Damara rams

• Forage soybean was ensiled with or without LAB inoculants and fed to rams.
• Fermentation of ensiled forage soybean was improved with Sil-All 4 × 4 inoculant.
• Lalsil Dry LB inoculant improved aerobic stability of ensiled forage soybean.
• Nutrient intake and digestion was improved with Sil-All 4 × 4 inoculant.

The study evaluated the effects of ensiling forage soybean (Glycine max (L.) Merr.) with or without bacterial inoculants on the fermentation characteristics, aerobic stability and nutrient digestion using rams. Forage soybean (cv. Link LF 6466) that contains 268 g dry matter (DM); 70 g water-soluble carbohydrates (WSC)/kg DM; 169 g crude protein (CP)/kg DM and pH of 7.04 was harvested at R6 stage, chopped to 15 mm length and ensiled in 210 L drums for 90 days. The forage was treated as follows: (i) control (2 L water/t), (ii) Lalsil Dry LB, a heterofermentative LAB inoculant (denoted as LDLB), and (iii) Sil-All 4 × 4® W.S. a homofermentative LAB inoculant (denoted as Sil). After 90 days of ensiling, forage soybean silage (FSS) samples were collected per treatment and analysed for fermentation characteristics and nutritive values. The FSS was top-dressed with 500 g concentrate and fed ad libitum to 18 (6 rams/treatment) matured Damara rams (48.2 ± 2.51 kg live weight) in a digestibility study. Sil inoculation improved (P < 0.05) the DM content while reducing (P < 0.05) the fibre fractions (aNDF and ADF) and ADL content of FSS compared to the other treatments. The LDLB treated FSS had a lower (P < 0.05) DM content (258 g DM/kg) and lactic acid content (LA) (38 g LA/kg DM) while the acetic acid content (AA) (51 g AA/kg DM) and ammonia-N (128.7 NH3-N/kg TN) were higher (P < 0.05) compared to other treatments. The reduced (P < 0.05) AA content (24.6 g AA/kg DM) in the Sil treated FSS resulted in a reduced (P < 0.05) aerobic stability of FSS as indicated by higher (P < 0.05) CO2 production (27.9 g CO2/kg DM) and reduced hours of aerobic stability of FSS compared to other treatments. The intake and digestibility of DM, OM and N were improved (P < 0.05) in rams fed the Sil inoculated FSS compared to other treatments. In contrast, the digestibility of fibre fractions was reduced (P < 0.05) in rams fed the Sil-treated FSS compared to other treatments.