Ensiling ability of species-rich mountain swards with elevated contents of condensed tannins

Ensiling forage from species-rich swards is challenging due to low contents of fermentable carbohydrates and a high buffering capacity due to potential protein degradation. Species-rich swards from two mountain meadows were investigated for their fermentation quality and effects of condensed tannins (CT) on protein degradation during ensiling. Swards were obtained from two long-term fertiliser experiments located in the Swiss Alps, cut two or three times during the season of 2017. Swards were either unfertilised or fertilised with PK or NPK. Forages were wilted and ensiled in laboratory silos. Composition of nutrients, protein and CT were determined in wilted and ensiled forage. The fermentation quality was analysed >65 d post ensiling. Silages were characterised by high pH (4.60-5.19) and butyric acid content (1.5-17.8 g kg‑1 dry matter (DM)), while ammonia-N ranged from 35 to 62 g kg‑1 of total N. Protein fraction A increased by 20.7% during ensiling. Contents of CT varied from 5.0 to 18.0 g kg‑1 DM.
Contents of CT were not consistently correlated to the increase in protein faction A when related to type of fertilisation or harvest.