Zum Proteinschutzpotential sekundärer Pflanzeninhaltsstoffe in alternativen Futterleguminosen und Wiesenkräutern

Amounts of rapidly rumen degradable protein in forage plants breed to a lower N-Use-Efficiency (NUE). Secondary plant metabolites, like tannins are able to protect forage protein against inefficient ruminal degradation. Feeding forage plants containing moderate concentrations of tannins may increase the sustainability in organic dairy production. This study was carried out to investigate the potential of several home-grown plants to bind forage protein and thus decrease ruminal N losses. A choice of six weeds and nine legumes were analyzed in terms of the composition of crude protein according to the Cornell Net Carbohydrate and Protein System, levels of condensed tannins (CT), total phenols (TP) and the ability to precipitate the model protein Bovines Serum Albumin (BSA). As it was expected sainfoin (Onobrychis viciifolia) and birdsfoot trefoil (Lotus corniculatus) showed above-average CT- and TP-concentrations as well as high protein precipitation capacities (PPC). Across the entire spectrum of species, a positive correlation between the CT concentration and the PPC was observed (p ≤ 0,001).Without any CT but highest TP concentration measured Salad Burnet (Sanguisorba minor) also showed protein precipitation capacities. This result indicates that CT concentration cannot be considered as the sole criterion for evaluating the protein binding capacity.