Effect of the stage of growth, wilting and inoculation in field pea (Pisum sativum L.) silages. II. Nitrogen fractions and amino acid compositions of herbage and silage

Abstract

The aim of the study was to investigate the effects of stage of maturity, wilting and inoculant application on proteolysis in field pea herbage and silage in northern Italy. Semi-leafless field peas were harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). For each stage of growth, the herbage was field wilted to a dry matter (DM) content around 330 g kg −1 . The unwilted and wilted herbages were ensiled with (I) and without (C) a lactic acid bacteria (LAB) inoculant. The stage of growth significantly affected all the nitrogen fraction concentrations both in herbage and in silage. Extensive proteolysis took place in silages made at early morphological stages and characterised by a high crude protein content (around 240 g kg −1 DM), as shown by the non-protein nitrogen (NPN) value (around 700 g kg −1 total N or higher). Neither inoculum nor wilting helped to reduce the protein degradation in these silages. The level of proteolysis was reduced in silages made from the pod filling stage onwards where most of the protein was localised in the seed and a better fermentation pattern was observed. The amino acid (AA) composition of silages made at stage IV was close to that of fresh herbage, with minimal losses of nutritionally essential amino acids for ruminants.

Characteristics of proteolytic microorganisms and their effects on proteolysis in total mixed ration silages of soybean curd residue

“…One of the most significant processes occurring during ensiling is the enzymatic degradation of protein to the NPN forms in silages. Even in well-preserved silages, approximately 50% degradation of protein may take place [24,25]. Alfalfa is particularly susceptible to proteolysis, because the proteinase activity is higher in this crop than in other grasses or legumes [26].…”

The effect of cultivar on the changes in protein quality during wilting and ensiling of red clover (Trifolium pratense L.)

“…Similar results have been demonstrated for alfalfa (Kohn & Allen 1995) and pea silages (Cavallarin et al . 2006). Therefore, the stage of maturity explains the variation in CP fraction A within years among the silages made from the red clover cultivars.…”

The effects of lactic acid bacteria strains isolated from various substrates on the fermentation quality of common vetch (Vicia sativa L.) in Tibet

“…However, the Achilles heel of conserving legume herbages is its relatively low concentration of fermentable carbohydrates in combination with the high buffering capacity (BC) and the low dry‐matter (DM) content (McDonald, Henderson, & Heron, ). Furthermore, high concentrations of crude protein in legume herbages promote extensive proteolysis during ensiling (Cavallarin, Antoniazzi, Tabacco, & Borreani, ). Several studies (see for instance Wang, Wang, Zhou, & Feng, ; Pursiainen & Tuori, ; Wen, Yuan, Wang, Desta, & Shao, ) have been thus used to manipulate fermentation patterns.…”