Preserving Porphyra umbilicalis and Saccharina latissima as Silages for Ruminant Feeding

Abstract

The study analyzed the characteristics, chemical composition, and in vitro gas production kinetics of Porphyra umbilicalis and Saccharina latissima silages. Each seaweed was ensiled in vacuum bags (three bags/silage) following a 2 × 3 factorial design, with two pre-treatments (unwilted or pre-wilted) and three silage types: unwashed seaweed ensiled without additive; seaweed washed and ensiled without additive; and seaweed washed and ensiled with 4 g of formic acid (FAC) per kg seaweed. Silages were kept for 3 months in darkness at 20 °C. Pre-wilting prevented (p < 0.001) effluent formation and reduced (p ≤ 0.038) the production of NH3-N and volatile fatty acids for both seaweeds. Both pre-wilting and washing increased (p < 0.05) the ruminal degradability of P. umbilicalis silages but not of S. latissima silages. The pH of the FAC-treated silages was below 4.0, but ranged from 4.54 to 6.23 in non FAC-treated silages. DL-lactate concentrations were low (≤23.0 g/kg dry matter) and acetate was the predominant fermentation product, indicating a non-lactic fermentation. The estimated ruminal degradability of the P. umbilicalis and S. latissima silages was as average, 59.9 and 86.1% of that for high-quality rye-grass silages, respectively, indicating a medium-low nutritional value of these seaweed silages for ruminants.

Improving fermentation of Saccharina latissima and Alaria esculenta silages with additives for preserving biomass and antioxidants

“…However, the total fermentation products were low in both seaweed silages (0.5-5% of DM) compared to common legume silages (0.8-11% DM) reported by Kung et al (2018), indicating a lower fermentation activity when ensiling seaweeds. Unlike terrestrial crops silages, where lactate is the major fermentation product, acetate was the major component in our seaweed silages, in accordance with results reported in a previous study (Novoa-Garrido et al 2020). High acetate and low lactate content in silages indicated limited lactic acid bacteria fermentation, and it can be explained by (1) the lack of epiphytic LAB in seaweed (< 10 3 CFU g −1 fresh biomass) (Uchida et al 2004;Herrmann et al 2015), (2) the low fermentation temperature (15 °C) used in present study, and (3) the high moisture content of biomass (DM < 30%) which prolonged the fermentation period required for the silage pH to be sufficiently low to favor the growth of Lactobacillus spp.…”

“…The DM content of pre-ensiling Alaria and Saccharina in present study was low but within the previously reported range of 5 to 36% DM in macroalgae (Zhang & Thomsen 2019) and was lower than that of the wild biomass collected in a close region (Tayyab et al 2016;Novoa-Garrido et al 2020). The chemical composition was within the range of the reported seasonal variation (Table 1) (Schiener et al, 2015).…”

“…The chemical composition was within the range of the reported seasonal variation (Table 1) (Schiener et al, 2015). Rinsing the seaweed biomass with water led to a lower ash content, as observed previously, thus rinsing is recommended in the seaweed silage making procedure (Novoa-Garrido et al 2020).…”

“…So far, there are only a few studies available that used either chemical or LAB additives in Saccharina silages (Cabrita et al 2017;Campbell et al 2020;Novoa-Garrido et al 2020). However, it is challenging to compare these results due to the differences in seaweed biomass and ensiling conditions.…”

Sustainable resource production for manufacturing bioactives from micro‐ and macroalgae: Examples from harvesting and cultivation in the Nordic region

“…Year‐round availability of stable raw material for further processing is important to facilitate growth in the macroalgae product sector. Some studies describe ensiling and fermentation of seaweeds for the production of biofuels (Herrmann et al, 2015; Sandbakken et al, 2018), food (Bruhn et al, 2019), or feeds (Campbell et al, 2020; Novoa‐Garrido et al, 2020), but effects on valuable ingredients such as proteins, carotenoids, or phenols are generally not evaluated in such studies. Ensiling of S. latissima was therefore tested in the NordAqua project to evaluate this process to ensure supply of year‐round availability of stable raw material for further processing and the effects of the treatment on the biochemical profile.…”