Fermentation characteristics and in vitro ruminal digestion of yacon residue silage with lactic acid bacteria inoculant or beet pulp

In this study, we examined the effects of lactic acid bacteria (LAB) inoculant and beet pulp (BP) on the quality of yacon (Smallanthus sonchifolius) residue silage. Yacon silage was prepared using a small-scale system of silage fermentation, and the treatments were as follows: control silage without any additive and silages with LAB inoculant Chikuso-1 (Lactobacillus plantarum, 5 mg/kg, fresh matter basis), BP (30% fresh matter basis), and LAB+BP. Silages were opened on days 3, 5, 7, 15, 30, and 60 of fermentation. The chemical composition, organic acid content, and in vitro ruminal digestion of the 60-day silage were determined. The pH of LAB-treated silage was lower than that of the silage without LAB. Furthermore, the LAB-treated silage presented the lowest ammonia-N concentration among the four types of silages, and it inhibited the growth of harmful bacteria including molds and clostridia during the early stages of fermentation. The BP-treated silage had lower contents of crude protein and ether extract than the silage without BP. The 60-day silage inoculated with LAB had the highest in vitro dry matter (DM) digestibility among the four silages, and the production of methane was lower than that of the silage treated with BP. The pH showed a tendency toward stabilization after 30 days of fermentation, although the concentration of lactic acid exhibited fluctuations during fermentation. The results suggest that the addition of LAB and BP can improve the fermentation quality of yacon silage, and the yacon silage with LAB might increase in vitro DM digestibility, but decrease in vitro ruminal methane production.