Cultivation and ensilage of yacon plants (Smallanthus sonchifolius [Poepp. & Endl.] H. Robinson) and the function of yacon silage

Yacon (Smallanthus sonchifolius [Poepp. & Endl.] H. Robinson) plant cultivation has extended rapidly throughout Japan since 1985 because of its utility as a tuberous root crop. In this study, strains with high yields of both above-ground and underground parts were identified to investigate the use of above-ground parts for animal feed silage. In addition, we measured the anti-oxidative activity of the silage as a functional characteristic. Data from 5 years of the cultivation of 17 yacon strains suggest that the most suitable strain for planting in the Aso region of Japan is SY217, which has a high yield of both above-ground parts and tuberous roots. The root tuber parts of yacon are used almost entirely as food; actually, most foliage parts are hardly used, except for some above-ground parts, which are used as tea. The fermentation qualities of the silage using all above-ground parts and harvest residue tuberous roots (harvest residues) are high and their dry matter digestibility, investigated using pigs, is 66.7%. Fresh above-ground parts had very strong anti-oxidative activity as compared with butylated hydroxyanisole and α-tocopherol. In addition, that activity is retained during ensiling for 4 weeks. These results suggest that the entire yacon plant can be used effectively as a feedstuff resource with the added bonus of anti-oxidant activity.