Effect of legume proportion and physiological age on forage quality and the suitability of Agrostis capillaris L. and Festuca rubra L. for silage making

The chemical and physical properties of herbage from low-input grassland usually differ from plant material of intensively managed swards. The experiment in split-plot design with four replicates was carried out to examine, whether legume proportions and the physiological age of herbage are relevant to fermentability of herbage. Lotus corniculatus did not increase nitrate concentrations sufficiently in Festuca rubra and most Agrostis capillaris swards to be able to avoid clostridial fermentation. However, Lotus corniculatus reduced the WSC/BC ratio of the grasses grown in mixture and that of the complete herbage of the mixtures. A late first cut in summer had an unexpected positive effect on the WSC/BC ratio of the grasses in pure stands, though reduced nutritive value of silages made from plants of advanced maturity stages are in all probability because of low energy concentrations in the fresh matter even with high yield proportions of the legume. Absence of fertilisation and late utilisation do not affect the chemical requirements for the fermentation process of grass-rich herbage in principle. However, silage making under these conditions is very demanding concerning ensilage technique: it may be necessary to use nitrate additives and higher fibre contents makes it more difficult to compact herbage.