The nutritional value to abalone of Ulva lactuca L with different tissue nitrogen levels was studied. The seaweed was cultured at two levels of ammonia-N enrichment. Cultures receiving 0.5 g ammonia-N m-2 d-1 ("Iow-N") yielded 164 g m-2 d-1 of fresh thalli containing 12% cmde protein in dry matter and 12 kJ g-l energy; cultures receiving 10 g ammonia-N m-2 d-1 ("high-N") produced 105 g of fresh thalli m~7 d-1 containing 44% protein and 16 kJ g-l energy. High-N and low-N algae and a "standard" mixed diet 005% U. lactuca and 25% Graci/aria conferta (w/w) containing 33% protein and 15 kJ g-l energy were fed to juvenile (0.7-2.1 g) an4 adult (6.9-19.6 g) Haliotis tuberclllata and H. discus hannai in a 16-week feeding trial. Voluntary feed intake of the high-N and slllndard diets were significantly lower than the low-N diet in all the cases. Clear differences in performance between treatments were found in the juvenile and adult abalone of both species. Juveniles fed high-N and standard diets grew significantly faster (specific growtb ratc'of H. tuberculata was 1.03% day-l on high-N algae as compared to 0.72% on low-N algae; H. discus hannai grew 0.63 and 0,3% d\\\\y-l on high-and low-N algae, respectively) and showed much better food conversion ratios. The nutritional value of Ulva lactuca to abalone is greatly improved by a high protein content, attainable by culturing the seaweed with high supply rates of ammonia.
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The aim of the present work was to evaluate the protein value of products from the two seaweeds Saccharina latissima and Palmaria palmata grown in Norwegian waters and to characterize possible beneficial or detrimental effects in the intestine and other organs. Mink, a well-established model for comparison of nutrient digestibility in monogastric animals was used. Two products from each of the seaweeds, a dried whole biomass and a protein concentrate, were evaluated. Five diets were made; a reference diet based on fish meal, and one for each of the four seaweed products. In the latter four, seaweed supplied 200 g/kg of crude protein. Each diet was fed to four male mink for two weeks. The results showed that diets with seaweed were less palatable than the fish meal diet. The animals fed the whole Saccharina diet had a significantly higher water intake and urine production than the other animals, supposedly due to the very high ash content of this seaweed product. This diet also stood out regarding urine concentration of iodine, which was 300 times higher than for the fishmeal-based diet. Apparent digestibility coefficient (ADC) for total amino acids, estimated by difference, showed low values for all the seaweed products; 0.574 and 0.734 for the whole and protein concentrated Saccharina products, and 0.588 and 0.700 for the two Palmaria products, respectively. The apparent amino acid digestibility coefficients (ADC) showed greater variation and were particularly low for histidine, <0.000 and 0.271 for the whole Saccharina and Palmaria products, respectively. Also, the ADC of methionine was low for these products, and cysteine ADC showed negative values for both Saccharina products. The estimated chemical score of the proteins, based on the digestible amino acids profile, was 0 and 520 g/kg for the whole product and protein concentrate of Saccharina, 260 and 520 g/kg for the whole product and the protein concentrate of Palmaria palmata, respectively. Expression of genes associated with digestive and immune functions showed minor effects in the jejunum, somewhat more pronounced effects in the colon. The latter effects were related to immune functions and lipid metabolism. No diet-related alterations in the histology of the jejunum and colon were observed. The histological investigation of liver and kidney structure showed some alterations in the seaweed fed animals. Regarding microbiota assemblage in mucosa of jejunum and colon, no clear diet effects were observed either in richness or diversity. In conclusion: the biological value of the seaweed proteins was low. Only one of the products, the Palmaria protein concentrate, might be considered of any use as a protein source. No clear beneficial or detrimental effects of the seaweed products were observed on gut health and function. The results regarding kidney structure and function, as well as the high iodine in the urine, indicating that further investigations are required to secure that animal health is not challenged by use of these seaweed ingredients in animal diets.
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The three seaweed species investigated had higher protein content in spring than in autumn. Both Porphyra and Acrosiphonia can supply the rumen with high amounts of rumen degradable protein but, due to both a high protein concentration and a low indigestible part, Porphyra can also supply a high amount of digestible protein to the small intestine. Pelvetia protein had a very low degradability in the rumen and the rumen escapable protein was not degradable in the small intestine, therefore, Pelvetia should not be used to feed dairy cows.
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Protoplast is an important tool for parasexual modification of genetic content of plant cells (Vasil and Vasil, 1980). Production of algal protoplasts and their fusion are relatively new fields and lag far behind that of terrestrial plants (Berliner 1981, 1983; Cheney et af., 1986). To date, protoplasts have been isolated from several algae, most of which are blue green algae and green algae (Adamich and Hemmingsen, 1980). Protoplasts have been obtained from some marine brown algae (Kloareg and Quantrano, 1987).
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Production of seaweeds by culture practices is done generally by vegetative propagation of small fragments of some agarophytes, alginophytes and carrageenophytes. Gracilaria edulis and Celidiella acerosa reach harvestable size after 2 and 21/2 months respectively when the seaweed is harvested and processed for agar extraction. India has a good scope for starting a seaweed culture industry based on the know-how available at the Central Marine Fisheries Research Institute.
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The aim of the present study was concentrates on different group of seaweeds like green (Ulva reticulata, Enteromorpha compressa, Cladophora glomerata, Halimeda macroloba and Halimeda tuna) brown (Dictyota dichotoma, Turbinaria ornata and Padina pavonica) and red (Gelidiella acerosa, Gracilaria crassa and Hypnea musciformis) were collected from Vedalai coastal waters, Southeast coast of India for analyzed proximate composition. The protein content was recorded maximum in G. acerosa and minimum in D. dichotoma; carbohydrate level was observed in T. ornata and minimum in P. pavonica. The lipid content was acquired higher level in H. tuna and minimum in H. macroloba.
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Growth, proximate composition, chlorophyll a, and carotenoid content were estimated in static cultures of micro alga Dunaliella salina (Dunal) Teod (Chlorophycea: Dunaliellaceae) to compare the quality and quantity of biomass produced with seaweed liquid fertilizer (SLF) against Walne’s medium. Culture of micro algae was performed with controlled temperature of 27 ± 1 °C, salinity of 33, and an irradiance of 120 ± 3 μ mol m–2 s –1, and daily samples were taken to estimate the above-mentioned parameters. Mean cellular density from samples of both medium were similar and growth rates were 0.44 and 0.42 doubling per day, respectively.
Maximum values of protein content 5.2 and 5.5 pg per cell were estimated on day 5 in Walne’s medium and SLF, respectively. Carbohydrate and lipid content decreased during the first 4 days corresponding to the culture exponential growth. Higher carbohydrate content was found in both media during the first 2 days and thereafter reduced partially compared to their concentrations. Generally lipid contents in cultures with SLF were significantly higher (P ≤0.05) compared to Walne’s medium. Both pigments also increased exponentially and their concentration was same in both experiments. In conclusion, all the parameters tested were similar when using either media, and hence SLF can be used as an alternate media for micro algal culture.
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Pulp & Paper, Bioethanol Made from Red Algae.
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The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N2 adsorption-desorption isotherms, and NH3 temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H2O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H2O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene, suggesting its potential as a transport fuel. The content of mono-aromatics with high economic value was also increased significantly by catalytic co-pyrolysis.
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In the coming decades, the world is going to face food-supply challenges, and aquaculture can contribute to feeding the growing world population sustainably. So why are more advancements not being made? John Forster of Forster Consulting in Washington, D.C., thinks general stagnation and regulatory smothering are suffocating offshore aquaculture’s potential. Forster talked to SeafoodSource recently about the problems, challenges and potential of offshore aquaculture.
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