Designing agricultural grasses to help mitigate proteolysis during ensiling to optimize protein feed provisions for livestock

Abstract

The efficient preservation of protein in silage for livestock feed is dependent on the rate and extent of proteolysis. Previous research on fresh forage indicated enhanced protein stability in certain Festulolium (ryegrass × fescue hybrids) cultivars compared to ryegrass. This is the first report of an experiment to test the hypothesis that a Lolium perenne × Festuca arundinacea var glaucescens cultivar had reduced proteolysis compared to perennial ryegrass (L. perenne) during the ensiling process. Forages were harvested in May (Cut 2) and August (Cut 4), wilted for 24 h and ensiled in laboratory-scale silos. Silage was destructively sampled at 0 h, 9 h, 24 h, 48 h, 72 h, 14 days and 90 days post-ensiling, and dry matter (DM), pH and chemical composition were determined. At Cut 2, there was no difference in crude protein between treatments but ryegrass had higher soluble nitrogen (SN) (P < 0.001) and grass × time interactions (p = 0.03) indicated higher rates of proteolysis. By Cut 4, Festulolium had (5.5% units) higher CP than ryegrass (p < 0.001) but SN did not differ. Ammonia-N did not differ between silages in either cut. DM differences (11.8% units) between treatments in Cut 4 (v.2.2% in Cut 2) may have masked effects on proteolysis, highlighting the importance of management on silage quality. This was despite higher WSC in ryegrass in both cuts (p < 0.001), with grass × time interactions (Cut 2; p = 0.03) showing slower WSC decline in ryegrass in Cut 4 (p < 0.001). Silage pH values did not differ between grasses in either cut, but grass × time interactions (p < 0.001) showed a slower decline in both ryegrass cuts, resulting in higher (p < 0.05) pH at 24 h and 72 h for Cuts 2 and 4, respectively.Overall, the hypothesis for an enhanced protein stability in Festulolium when ensiled as ruminant feed was evidenced by lower SN but not ammonia-N in an earlycut silage with a comparable DM to ryegrass.

The Silage Quality of Pennisetum purpureum Cultivar Gamma Umami Mixed with Calliandra calothyrsus and Lactiplantibacillus plantarum

“…The higher the pH of the resulting silage, the higher the proteolytic activity. Muhandiram et al (2023) stated that a rapid decrease in pH can help inhibit proteolysis, thereby maintaining the protein content of the silage. Low pH values at the beginning of the ensiling process help prevent protein breakdown into NH 3 -N. Our result was slightly higher than found in the mixed silage of high moisture amaranth and rice straw treated with L. plantarum NH 3 -N of (3.07 mg/100 g) (Kim et al, 2017b), which might be due to different silage base materials used in each of these studies.…”

“…Thus, the concentration of NH 3 -N is associated with the level of protein degradation both by plant enzymes and microbial enzyme activity, which acts as a secondary fermenter by Enterobacteria, Clostridia (butyric acid producer), and yeasts (ethanol producer) (Kim et al, 2021). However, the efficiency of rumen microbial N-synthesis can be increased by supplementing the silage with N-protein rather than non-protein nitrogen (NPN); thus, reduced proteolysis during ensilage is essential (Muhandiram et al, 2023).…”