New challenges for efficient usage of Sargassum fusiforme for ruminant production

Unusual holopelagic Sargassum mass beaching in Northwest Africa: Morphotypes, chemical composition, and potential valorisation

The rapid proliferation of holopelagic Sargassum spp. in the tropical Atlantic Ocean presents environmental challenges and economic opportunities. In 2022, Senegal witnessed its first significant holopelagic Sargassum beaching event, triggering widespread concern and interest from civil society, industrial sectors, and government. This study represents the first analysis of stranded holopelagic Sargassum's morphotypes and chemical composition in Northwest Africa. We highlight the nature of Sargassum stranding, dominated by S. fluitans III, and describe a putative new morphotype. Compared to most of the studies in the tropical Atlantic, Senegalese Sargassum displayed lower arsenic concentrations (9-29 ppm), higher cadmium levels (9-15 ppm), and increased mercury content (0.47-0.57 ppm). In addition, Senegalese Sargassum showed higher levels of iron (237-1017 ppm) and phosphorus (1300-1772 ppm). The biochemical analysis revealed high total protein levels (15-40 % DW) in Senegalese samples, though further analysis is required to confirm this. Furthermore, variations in biochemical composition within various parts of the Sargassum thallus were observed. The low arsenic content makes the beached Senegalese Sargassum attractive for valorisation and sets it apart from holopelagic Sargassum from all other regions where it occurs. However, caution should be taken regarding the high concentrations of cadmium. Our study highlights promising applications in Senegal and neighbouring countries, particularly in animal feed and agriculture. Noteworthy is the notable palladium content (2 ppm), valuable phenolic compounds, and mannitol, which present additional opportunities for the chemical industry. Our interdisciplinary approach enhances the global scientific understanding of the Sargassum issue. With the anticipation of more frequent Sargassum beaching events and, more generally, for seaweed exploitation, we advocate for inter-governmental African organisations to establish standardised norms for their exploitation. We recommend that the Food and Agriculture Organization/World Health Organization consider incorporating more seaweed in the Codex Alimentarius to facilitate their uses particularly when states deal with algal blooms.

Brown algae biomass for fucoxanthin, fucoidan and alginate; update review on structure, biosynthesis, biological activities and extraction valorisation

Natural compounds promoting human health are the main focus of research nowadays. Fucoxanthin, fucoidan and alginate are such bioactive compounds that are extracted from marine brown algae. Extracting these 3 compounds through successive extraction enhances the commercial value of the brown algae biomass. There are studies on successive extraction of fucoidan and alginate but not with fucoxanthin which displays various biological bioactivities. Alginate, a polysaccharide presents 45 % in the cell wall of brown algae. Fucoidan, a sulphated polysaccharide proved showing various bioactivities. These bioproducts yield are vary depending on the species. Dictyota species recorded high fucoxanthin content of 7 %. Ascophyllum nodosum was found with high fucoidan of 16.08 % by direct extraction. Maximum alginate of 45.79 % was recorded from the brown alga Sargassum cymosum and by successive extraction 44 % was recorded from Ecklonia radiata. Fucoxanthin exits in two isomers as trans and cis forms. Based on linkage, fucoidan structure is found in 3 forms as 1,3- or 1,4- or alternating 1,3- and 1,4-linked fucose in the polysaccharide residues. Fucoidan composition varys depending on the degree of sulphation, composition of monosaccharides and location of collection. In alginate, its property relies on the mannuronic acid and guluronic acid composition. Biosynthesis of these 3 compounds is not much explored. Keeping this view which signify sequential extraction towards biomass valorisation, fucoxanthin, fucoidan and alginate extracted from the brown algae species focusing yield, extraction, characterisation, biosynthesis and biological activities were compiled and critically analysed and discussed in this review.

Effect of Padina gymnospora biowaste inclusion on in vitro methane production, feed fermentation, and microbial diversity

In vitro studies were undertaken aiming to study the methane (CH4) mitigation potential of biowaste (BW) of Padina gymnospora at the graded inclusion of 0% (C), 2% (A2), 5% (A5), and 10% (A10) of the diet composed of straw and concentrate in 40:60 ratio. The chemical composition analysis revealed that the BW contained higher crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and ether extract (EE) than the PF (fresh seaweed, P. gymnospora). The concentration of cinnamic acid, sinapic acid, kaempferol, fisetin p-coumaric acid, ellagic acid, and luteolin in BW was 1.5-6-folds less than the PF. Inclusion of BW decreased (P < 0.0001) CH4 production by 34%, 38%, and 45% in A2, A5, and A10 treatments, respectively. A decrease (P < 0.0001) of 7.5%-8% in dry matter (DM) and organic matter (OM) digestibility was also recorded with the BW supplementation. The BW inclusion also decreased the numbers of total (P = 0.007), Entodinomorphs (P = 0.011), and Holotrichs (P = 0.004) protozoa. Metagenome data revealed the dominance of Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria, and Fibrobacter microbial phyla. At the phylum level, Euryarchaeota dominated the archaeal community, whereas Methanobrevibacter was most abundant at the genus level. It can be concluded that the inclusion of BW in straw and concentrate based diet by affecting rumen fermentation, protozoal numbers, and compositional shift in the archaeal community significantly decreased CH4 production. Utilization of biowaste of P. gymnospora as a CH4 mitigating agent will ensure its efficient utilization rather than dumping, which shall cause environmental pollution and health hazards.

Potential use of seaweed as a dietary supplement to mitigate enteric methane emission in ruminants

Seaweeds or marine algae exhibit diverse morphologies, sizes, colors, and chemical compositions, encompassing various species, including red, green, and brown seaweeds. Several seaweeds have received increased research attention and application in animal feeding investigations, particularly in ruminant livestock, due to their higher yield and convenient harvestability at present. Recent endeavors encompassing both in vitro and in vivo experiments have indicated that many seaweeds, particularly red seaweed (Asparagopsis taxiformis and Asparagopsis armata), contain plant secondary compounds, such as halogenated compounds and phlorotannins, with the potential to reduce enteric ruminal methane (CH4) emissions by up to 99 % when integrated into ruminant diets. This review provides an encompassing exploration of the existing body of knowledge concerning seaweeds and their impact on rumen fermentation, the toxicity of ruminal microbes, the health of animals, animal performance, and enteric ruminal CH4 emissions in both in vitro and in vivo settings among ruminants. By attaining a deeper comprehension of the implications of seaweed supplementation on rumen fermentation, animal productivity, and ruminal CH4 emissions, we could lay the groundwork for devising innovative strategies. These strategies aim to simultaneously achieve environmental benefits, reduce greenhouse gas emissions, enhance animal efficiency, and develop aquaculture and seaweed production systems, ensuring a high-quality and consistent supply chain. Nevertheless, future research is essential to elucidate the extent of the effect and gain insight into the mode of action.

Role of Polysaccharides from Marine Seaweed as Feed Additives for Methane Mitigation in Ruminants: A Critical Review

Given the increasing concerns regarding greenhouse gas emissions associated with livestock production, the need to discover effective strategies to mitigate methane production in ruminants is clear. Marine algal polysaccharides have emerged as a promising research avenue because of their abundance and sustainability. Polysaccharides, such as alginate, laminaran, and fucoidan, which are extracted from marine seaweeds, have demonstrated the potential to reduce methane emissions by influencing the microbial populations in the rumen. This comprehensive review extensively examines the available literature and considers the effectiveness, challenges, and prospects of using marine seaweed polysaccharides as feed additives. The findings emphasise that marine algal polysaccharides can modulate rumen fermentation, promote the growth of beneficial microorganisms, and inhibit methanogenic archaea, ultimately leading to decreases in methane emissions. However, we must understand the long-term effects and address the obstacles to practical implementation. Further research is warranted to optimise dosage levels, evaluate potential effects on animal health, and assess economic feasibility. This critical review provides insights for researchers, policymakers, and industry stakeholders dedicated to advancing sustainable livestock production and methane mitigation.

Effect of Pelagic Sargassum on In Vitro Dry Matter and Organic Matter Degradation, Gas Production, and Protozoa Population

This study determined the effect of pelagic Sargassum on in vitro dry matter and organic matter degradation, total gas production (TGP), and protozoa population. The treatments were different levels of Sargassum inclusion on a basal substrate (Stargrass hay; Cynodon nlemfuensis) as follows: T0 (control treatment based on Stargrass hay), T10 (90% Stargrass hay + 10% Sargassum), T20 (80% Stargrass hay + 20% Sargassum), and T30 (70% Stargrass hay + 30% Sargassum). Ruminal fermentation kinetics and protozoa population were determined during 72 h of in vitro incubations. Compared to control, dry matter degradability at 48 and 72 h and organic matter degradability at 24 and 48 h were higher in Sargassum treatments. TGP was lower with T20 at 48 h. The total population of protozoa and the concentration of Entodinium spp. were lower at T20 at 48 h and T30 at 72 h. Cl, S, Ca, K, and Zn (103, 5.97, 88.73, 285.70 g/kg, and 15,900 mg/kg) were high in Sargassum, reaching twice or even nine times higher than the contents in Stargrass (11.37, 1.60, 43.53, 87.73 g/kg, and 866.67 mg/kg). Overall, up to 30% pelagic Sargassum could be included in hay-based substrates from tropical grasses without negative effects on in vitro dry matter and organic matter degradability.

Potential of Seaweeds to Mitigate Production of Greenhouse Gases during Production of Ruminant Proteins

The potential of seaweed to mitigate methane is real and studies with red seaweeds have found reductions in methane produced from ruminants fed red seaweeds in the region of 60-90% where the active compound responsible for this is bromoform. Other studies with brown and green seaweeds have observed reductions in methane production of between 20 and 45% in vitro and 10% in vivo. Benefits of feeding seaweeds to ruminants are seaweed specific and animal species-dependent. In some instances, positive effects on milk production and performance are observed where selected seaweeds are fed to ruminants while other studies note reductions in performance traits. A balance between reducing methane and maintaining animal health and food quality is necessary. Seaweeds are a source of essential amino acids and minerals however, and offer huge potential for use as feeds for animal health maintenance once formulations and doses are correctly prepared and administered. A negative aspect of seaweed use for animal feed currently is the cost associated with wild harvest and indeed aquaculture production and improvements must be made here if seaweed ingredients are to be used as a solution to control methane production from ruminants for continued production of animal/ruminant sourced proteins in the future. This review collates information concerning different seaweeds and how they and their constituents can reduce methane from ruminants and ensure sustainable production of ruminant proteins in an environmentally beneficial manner.

Effects of seaweed extracts on in vitro rumen fermentation characteristics, methane production, and microbial abundance

Several seaweed extracts have been reported to have potential antimethanogenic effects in ruminants. In this study, the effect of three brown seaweed species (Undaria pinnatifida, UPIN; Sargassum fusiforme, SFUS; and Sargassum fulvellum, SFUL) on rumen fermentation characteristics, total gas, methane (CH4), carbon dioxide (CO2) production, and microbial populations were investigated using an in vitro batch culture system. Seaweed extract and its metabolites, total flavonoid and polyphenol contents were identified and compared. For the in vitro batch, 0.25 mg∙mL-1 of each seaweed extract were used in 6, 12, 24, 36 and 48 h of incubation. Seaweed extract supplementation decreased CH4 yield and its proportion to total gas production after 12, 24, and 48 h of incubation, while total gas production were not significantly different. Total volatile fatty acid and molar proportion of propionate increased with SFUS and SFUL supplementation after 24 h of incubation, whereas UPIN was not affected. Additionally, SFUS increased the absolute abundance of total bacteria, ciliate protozoa, fungi, methanogenic archaea, and Fibrobacter succinogenes. The relative proportions of Butyrivibrio fibrisolvens, Butyrivibrio proteoclasticus, and Prevotella ruminicola were lower with seaweed extract supplementation, whereas Anaerovibrio lipolytica increased. Thus, seaweed extracts can decrease CH4 production, and alter the abundance of rumen microbial populations.

Effects of Olive (Olea europaea L.) Leaves with Antioxidant and Antimicrobial Activities on In Vitro Ruminal Fermentation and Methane Emission

We evaluated whether olive leaves (OLs) are effective as feed additives and supplements for ruminants and the potential methane reduction effects during in vitro fermentation. Two Hanwoo cows (460 ± 20 kg) equipped with cannula were fed Timothy hay and corn-based feed 3% of the body weight at a ratio of 6:4 (8:30 a.m. and 5:00 p.m.). Ruminal fluid from the cows was collected and mixed before morning feeding. In vitro batch fermentation was monitored after 12 and 24 h of incubation at 39 °C, and OLs were used as supplements to achieve the concentration of 5% in the basal diet. At 12 h of fermentation, methane production decreased in the 5% OLs group compared to that in the control group, but not at 24 h. The proportion of cellulose-degrading bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens, tended to increase in the 5% OLs group at 12 h. The amount of ammonia produced was the same as the polymerase chain reaction result for Prevotella ruminicola. At 12 h, the proportion of Prevotella ruminicola was significantly higher in the 5% OLs group. OLs may be used incorporated with protein byproducts or other methane-reducing agents in animal feed.

Selected Alternative Feed Additives Used to Manipulate the Rumen Microbiome

Simple Summary

The continuous intensification of ruminant production drives towards the expansion of feed components and additives that are utilizes for the coverage of animal’s demand for nutrients. Additionally, in recent years, studies are focused on the investigation of how feed additives affect the microbiome of the digestive system in order to obtain improved performance and/or reduce methane emissions by ruminants. The use of additives such as algae, probiotics, fermented feed or essential oils can serve as an alternative to antibiotics or other synthetic compounds that may pose a danger to the environment.

Abstract

In recent years, a boost in the ruminant population has been observed, and consequently, an increase in the animals’ demand for nutrients and methane emissions. Methane emission is generated during the microbial fermentation of feed in the rumen, and a percentage even up to 12% of the energy obtained by this process can be wasted. In addition, the use of antibiotics in animal husbandry is being increasingly restricted. restricted. As a result, there is a continuous search for innovative feed additives that can serve as alternatives to antibiotics, and will also be safe for both people and the environment. In the present review article, additives were selected on basis that, according to studies conducted so far, may positively affect the microbiome of the digestive system by improving indicators and/or reducing methane production. Among them, probiotics, prebiotics or their combination—synbiotics are at the forefront of research. However, additives in the form of algae or plant origin are also gaining ground in popularity, such as essential oils, fermented wheat straw or Gelidium amansii, due to their general recognition as safe (GRAS) for both humans and environment.