Effect of commercial lactic acid bacteria inoculants on the fermentation dynamics ofyacon (Smallanthus sonchifolius) harvest-residue silage

Abstract

Smallanthus sonchifolius (yacon) is an Andean plant whose tuberous roots are widely used for human consumption owing to their high fructooligosaccharide content. The aerial biomass generated as a post-harvest residue can be preserved as silage to serve as a feed resource for livestock. Silage pH is a reliable indicator of fermentation progress and can be used to monitor the acidification process. The addition of lactic acid bacteria (LAB) inoculants accelerates fermentation by promoting a directed microbial pathway that lowers pH and extends forage preservation. The objective of this study was to determine the fermentation dynamics of yacon harvest-residue silage prepared with different commercial LAB inoculants at varying inclusion rates, using pH as the primary fermentation indicator. Silages were prepared from post-harvest aerial plant material with 67% moisture content, chopped to 1 cm particle size and packed into PVC microsilos (10 cm diameter × 20 cm height). Each microsilo received 1 kg of fresh matter (FM), achieving a mean compaction density of 640 ± 40 kg m^-3. A completely randomized design was used with five treatments and four replicates: T1, uninoculated control; T2, liquid inoculant at 250 g t^-1 FM; T3, liquid inoculant at 500 g t^-1 FM; T4, solid inoculant at 250 g t^-1 FM; and T5, solid inoculant at 500 g t^-1 FM. pH was measured at days 0, 1, 5, 10, 20 and 40. A significant decline in pH was observed across all treatments from day 5 onwards. By day 10, T3 reached the lowest pH value (4.67), differing significantly from T1. On day 40, T4 and T5 exhibited the lowest pH values (4.34 and 4.36, respectively), which were significantly lower than those recorded for T2 and T3. All treatments reached pH values considered acceptable for silage preservation by day 40, with treatments differing primarily in the rate of acidification rather than in the final fermentation outcome.