Enhanced lactic acid fermentation of silage by the addition of green tea waste

The effects of green tea waste (GTW) addition on the ensiling of forage were investigated. Wet and dried GTW added at 10, 50, 100 and 200 g kg^-1 of fresh matter (FM) and at 2, 10 and 20 g kg^-1 FM, respectively, decreased pH and increased lactic acid concentration of the silages, whereas the butyric acid concentration and ammonia nitrogen content, as a proportion of a total nitrogen, were lowered, compared with silage without additives (control). To investigate the effect of GTW-associated LAB on silage fermentation, wet GTW was sterilized by autoclaving or gamma irradiation and added at 50 g kg^-1 FM. The silages made with sterilized GTW showed higher lactic acid concentrations, and lower pH and butyric acid concentrations than controls. The counts of lactic acid bacteria (LAB) were higher in silages made with sterilized GTW than control until 10 days after ensiling. The enhanced lactic acid fermentation was not found when green tea polyphenols (GTP) were added. These data suggested that GTW could enhance LAB growth and lactic acid production of silage, particularly when added at 50 g kg^-1 FM in a wet form or at the equivalent in a dry form. Although neither GTW-associated LAB nor GTP accounted for the enhancement of lactic acid fermentation, GTW would possibly supply some nutrients which are heat -stable and effective for LAB growth during silage fermentation.