Nutritive value of tall fescue (Festuca arundinacea Schreb.) silage under practical conditions

Tall fescue (Festuca arundinacea Schreb.) is gaining interest among Belgian dairy farmers due to its higher drought resistance and expected higher dry matter yield compared with perennial ryegrass (Lolium perenne L.). Digestibility of tall fescue under fresh conditions is lower than that of perennial ryegrass; however knowledge of digestibility of ensiled tall fescue is sparse, which makes it hard for farmers to assess the impact of replacing perennial ryegrass with tall fescue in part of their grasslands. We have started a small-scale experiment at farm level to test the digestibility of ensiled tall fescue. The management of one monoculture of both grasses in 2017 and 2018 was studied on three farms. Fresh grass samples were taken immediately before every cut, and immediately before the grass was ensiled samples of perennial ryegrass and tall fescue were ensiled in small containers. Digestibility, ash, crude fibre and crude protein content were determined by NIRS and parameters were recalculated to provided in vivo digestibility. The results revealed that in 2017 differences in digestibility between fresh tall fescue and fresh perennial ryegrass disappeared after ensiling, but not in 2018. There is no clear explanation for the between-years difference for this effect of the silage process.