Evaluation of red seaweed Gracilaria arcuata as dietary ingredient in African catfish, Clarias gariepinus

Dietary Effect of Padina boergesenii on Growth, Immune Response, and Disease Resistance Against Pseudomonas aeruginosa in Cirrhinus mrigala

In the aquatic environment, seaweeds have the potential to be renewable resources. The current study was designed to assess the impact of seaweed Padina boergesenii incorporated into a basal diet at various concentrations. The phytoconstituents of the seaweeds were characterised by gas chromatography-mass spectrometry. Diets were designed to include elevated levels of 0.5%, 2.5%, 4.5%, and 6.5% of seaweed meal. Significant differences in Cirrhinus mrigala fed with P. boergesenii incorporated into the basal diet for 45 days. The growth parameters (weight gain, specific growth rate), biochemical constituents, and immunological assays were observed. The extract fraction demonstrated effective inhibitory activity against Pseudomonas aeruginosa. As a result, this research suggests that extracts of the seaweed P. boergesenii contain potential bioactive compounds with significant antibiotic activity.

Integrated marine microalgae biorefineries for improved bioactive compounds: A review

Marine microalgae offer a promising feedstock for biofuels and other valuable compounds for biorefining and carry immense potential to contribute to a clean energy and environment future. However, it is currently not economically feasible to use marine algae to produce biofuels, and the potential bioactive chemicals account for only a small market share. The production of algal biomass with multiple valuable chemicals is closely related to the algal species, cultivation conditions, culture systems, and production modes. Thus, higher requirements for screening of dominant algal strains, developing integrated technologies with the optimum culture conditions, efficient cultivation systems, and production modes to exploit algal biomass for biorefinery applications, are all needed. This review summarizes the screening of dominant microalgae, discusses the environmental conditions that may affect the growth, as well as the culture systems and production modes, and further emphasizes the valorization options of the algal biomass, which should help to offer a sustainable approach to run a profitable marine algae production system.

Spent Mushroom Substrate Based Fish Feed Affects The Growth of Catfish (Clarias gariepinus)

A preliminary study was conducted to identify the effect of Spent Mushroom Substrate (SMS), a biomass from mushroom cultivation, towards catfish growth and intake performance when developed into fish feed. The fish experiment on catfish was conducted up to 12 weeks and analyzed on the weight, length size, survival rate and digestibility for the three types of SMS based feed in pellet form and a commercial pellet that applied for ten catfish each. Among the SMS based fish feed, Ganoderma obtained the highest weight of 32.46 g followed by White (30.71 g) and Abalone (17.74 g). For the length size, Ganoderma, White and Abalone SMS based feed had achieved in average 18.05 cm, 17.12 cm and 14.85 cm respectively. Commercial feed still manage to obtain the highest weight and length size as 39.33 g and 20.83 cm respectively. The survival rate was found 30 % higher in SMS based feed compared to commercial feed. The digestibility study of dry matter for Ganoderma, White and Abalone SMS based feed were found 77.34 %, 78.20 %, 77.76 % respectively whereas for commercial pellet was 60.92 % indicates that SMS based feed was consumed and digested better than commercial feed.

Immunomodulation, antioxidant enhancement and immune genes up-regulation in rainbow trout (Oncorhynchus mykiss) fed on seaweeds included diets

This study investigated the stimulatory effects of dietary inclusion of Gracilariopsis persica (GP), Hypnea flagelliformis (HF) and Sargassum boveanum (SB) on immune indices, antioxidant capability and immune related genes expression of rainbow trout (Oncorhynchus mykiss). Seven iso-nitrogenous and iso-caloric diets with 0, 5 and 10% of each macroalgae were prepared and fed to rainbow trout juveniles for 83 days. Serum lysozyme (Lyz) and respiratory burst activity (NBT) along with activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and expression of LyzII, TNFα and IL-1β genes in head kidney samples were determined by days 47 and 83. Our results revealed that dietary inclusion of seaweeds improved fish immune status. Long term feeding of fish on seaweed contained diets (except for GP10) improved serum Lyz activity in comparison to control group. Similarly, extended feeding on GP5 and HF10 and HF10 included diets improved SOD and POD levels, respectively. Genes expression studies revealed that seaweeds contained diets noticeably enhanced expression of LyzII, TNFα and IL-1β in comparison to control fish. However, results revealed that such stimulatory effects were more evident at lower dietary inclusion level and shorter feeding time. In conclusion, the results depicted that dietary inclusion of the seaweeds effectively improved serum immune indices and head kidney antioxidant status and immune related genes expression in a time and dose dependent manner.

Seaweed Potential in the Animal Feed: A Review

Seaweed (known as marine algae) has a tradition of being part of the animal feed in the coastal areas, from ancient times. Seaweeds, are mixed with animal feed, because when consumed alone can have negative impact on animals. Thus, seaweeds are very rich in useful metabolites (pigments, carotenoids, phlorotannins, polyunsaturated fatty acids, agar, alginate and carrageenan) and minerals (iodine, zinc, sodium, calcium, manganese, iron, selenium), being considered as a natural source of additives that can substitute the antibiotic usage in various animals. In this review, we describe the nutritional values of seaweeds and the seaweed effects in the seaweed-based animal feed/supplements.

Viability of dietary substitution of live microalgae with dry Ulva rigida in broodstock conditioning of the Pacific oyster (Crassostrea gigas)

The current study evaluated the microalgae replacement by dry macroalgae (Ulva rigida) in the reproductive success and biochemical composition of the Pacific oyster (Crassostrea gigas) during broodstock conditioning. Five nutritional regimes were tested: 100% macroalgae (diet 1), 50% macroalgae+50% microalgae (diet 2), 25% macroalgae+75% microalgae (diet 3) and 100% microalgae (diet 4). An unfed group was used as a negative control. The microalgae blend was composed of 33% Isochrysis galbana and 67% diatoms (75% Skeletonema costatum+25% Chaetoceros calcitrans). Gonadal maturation was reflected in the physiological condition of the individuals. All treatments, except diet 1, showed an increase in condition index and were fully matured at the end of the trial, with the best physiological condition observed in oysters fed diet 3 and diet 4. Protein and total lipid content increased during the conditioning period, whereas glycogen content decreased. Oysters conditioned with diet 3 had higher protein and total lipid content and lower glycogen content than the other treatments. In addition, diet 3 showed the highest percentage of viable veliger larvae. The current study demonstrated that it is possible to replace 25% of microalgae with macroalgae in the broodstock conditioning, minimizing the operative cost in bivalve hatcheries.

This article has an associated First Person interview with the first author of the paper.

Summary: The use of an alternative diet with 25% microalgae replacement by dry macroalgae is beneficial during broodstock conditioning and allows the operation costs of bivalve hatcheries to be minimized.

Searching for antigenotoxic properties of marine macroalgae dietary supplementation against endogenous and exogenous challenges

The functional characterization of marine macroalgae toward their potential to strength genome protection is still scarce. Hence, the aim of this study was to assess the antigenotoxic potential of Ulva rigida, Fucus vesiculosus, and Gracilaria species in Drosophila melanogaster following dietary exposure and adopting the somatic mutation and recombination test (SMART). All macroalgae displayed a genoprotection activity, namely against an exogenous challenge (streptonigrin). The action against subtler endogenous pressures was also noted indicating that supplementation level is a critical factor. Gracilaria species provided ambivalent indications, since 10% of G. vermiculophylla inhibited the egg laying and/or larvae development, while 10% of G. gracilis promoted spontaneous genotoxicity. The effects of U. rigida were modulated (in intensity) by the growing conditions, demonstrating higher genoprotection against streptonigrin-induced damage when grown in an aquaculture-controlled system, while the effectiveness against spontaneous genotoxicity was more apparent in specimens grown under wild conditions. In contrast, F. vesiculosus did not produce significant differences in its potential under varying growing conditions. Overall, these findings shed some light on the macroalgae ability toward genome protection, contributing to the development of algaculture industry, and reinforcing the concept of functional food and its benefits.