The aim of the study was to determine changes in nitrogen fractions during the ensiling of lucerne and red clover herbage in bales. Protein nitrogen and non-protein nitrogen compounds in herbage and silage were distinguished. Furthermore, buffer soluble nitrogen compounds (BSN) were determined and divided into buffer soluble protein and non-protein nitrogen (BSPN and NPBSN, respectively). In addition, peptide nitrogen and amino acid nitrogen were distinguished within the NPBSN fraction, while nitrogen compounds were divided into those of low solubility (NDIN) and completely insoluble (ADIN). The research findings confirmed the effect of a legume plant species on changes in the content of nitrogen fractions during the ensiling in round bales. The ensiling of lucerne herbage grossly decreased the protein nitrogen fraction while raising the total soluble fraction of nitrogen. Nitrogen in the form of soluble proteins, NDIN and ADIN was the least affected. The study demonstrated a different response of the two legume plant species to ensiling with respect to all fractions. A high proportion of protein nitrogen in round bale wilted red clover silage was accompanied by a large contribution of insoluble nitrogen fractions. A large share of the protein nitrogen fraction in red clover silage does not necessarily mean a higher nutritional value of the protein because it may contain a large amount of protein compounds that are non-hydrolysable by bacterial and intestinal enzymes. 

20.2.2015