Changes during ensilage in the nitrogenous components of fresh and additive treated ryegrass and lucerne

The changes in the major nitrogenous components of herbage during the ensilage of lucerne and Italian ryegrass, with and without the addition of 85% formic acid and 40% formaldehyde at the rates of 3.2 and 7.4 g kg −1 fresh herbage respectively, were studied. Both herbages were of similar amino‐N composition except for asparagine which was about 10% of total nitrogen (TN) in lucerne and only 0.2% of TN in Italian ryegrass. After 90 days ensiling about 90% of the sum of protein‐, peptide‐, amino‐ and amide‐N was preserved in the additive‐treated silages while only 58% was recovered in the untreated lucerne (butyrate) silage. Recoveries of these compounds in the untreated ryegrass (lactate) silage was 83%. In the butyrate silage, the branched chain amino acids, valine, leucine and isoleucine were well preserved. In addition to these, proline, phenylalanine, glycine, methionine and threonine were well preserved in the lactate silages. Both the untreated silages contained more alanine than in their original respective herbages. Most of the losses from the amine‐forming amino acids were recovered as their corresponding amines. Alpha‐amino butyric acid and δ‐amino valeric acid were found in both the untreated silages and the quantity present was dependent on the silage quality. In both the additive‐treated silages, recoveries of amino acids, other than sulphur amino acids, lysine, histidine, tyrosine and tryptophan, were ca 90% or greater. The losses of these amino acids, excluding the sulphur amino acids, can be attributed mainly to the direct effects of formaldehyde in preventing their estimation following freeze drying or acid hydrolysis.