High Highly Unsaturated Fatty Acids Research Articles

Effects of enrichment Artemia with organic selenium and essential fatty acids on growth performance and fatty acid composition of barramundi (Lates calcarifer) larvae

A feeding factorial experiment was conducted, in which Artemia was enriched with two organic selenium (Se) concentrations (0, 12 mg/L) and three highly unsaturated fatty acids (HUFA) levels (0, 0.3 and 0.6 g/L) to produce six dietary treatments, labelled as H0, H03, H06, H0S; H03S and H06S. The diets were fed to barramundi larvae (11 day after hatching) for 15 days to investigate the combined effects of selenium and HUFA on growth performance, fatty acid composition, skeletal deformities and stress resistance of the larvae. The results showed that enriching Artemia with Se significantly improved the final weight and specific growth rate of the larvae fed non or highest HUFA enrichment levels (P < 0.05). No differences were observed in survival of the larvae fed enriched HUFA diets, but they were significantly higher than those fed unenriched HUFA groups. Dietary Se supplementation significantly increased larval n-3 HUFA and DHA contents. High mortalities were recorded in the larvae fed unenriched HUFA diets, whereas Se supplementation significantly increased the survival of the larvae fed high HUFA level. Fish fed unenriched HUFA Artemia showed significantly higher skeletal deformities than those fed other diets. The results thus indicated the beneficial effects of dietary Se in preventing the reduced growth and stress resistance in the barramundi fed HUFA inclusion diets.

Effects of Atlantic salmon (Salmo salar) fed low- and high HUFA diets on growth and midgut intestinal health

For a rapidly developing aquaculture industry where availability of raw materials for diet formulation are quickly changing it is fundamental to define what the dietary needs and benefits are. In farming of Atlantic salmon (Salmo salar), highly unsaturated fatty acids (HUFA) are known to be essential and a minimum dietary inclusion is needed. The aim of this study has been to map Atlantic salmon performance and midgut health towards dietary HUFAs under normal and challenging condition. Atlantic salmon post-smolt at 150 g were fed four experimental diets over a feeding period of 10 weeks up to a final weight of 377 g followed by three weeks of unpredictable chronic stress (UCS). The diets varied in their HUFA level, with either 28.7 g/kg DHA (HDHA), 25 g/kg EPA (HEPA), 21.3 g/kg ARA (HARA) or 8.5 g/kg EPA + DHA (LHUFA). After the feeding period all fish had more than doubled their weight and fish fed HARA showed a significant lower specific growth rate compared to all other diets. Diets had little effect on intestinal morphology, barrier and transport function. Intestinal polar lipid composition suggested higher lipid metabolism in fish feed LHUFA and transcriptome analysis confirm upregulated lipid metabolism and downregulated energy turn over. Comparing transcriptome profiles from HDHA to HEPA, more upregulated pathways are seen in fish fed HEPA, including metabolism and immunity. The fish feed HARA had downregulated turn-over and metabolism compared to fish fed HEPA. The UCS period resulted in zero growth and lower enterocyte height in all diet groups, and the intestinal barrier was reduced in the paracellular permeability to mannitol. Contradictory to previous studies, fish fed HDHA and HEPA responded to UCS with enhanced intestinal resistance. UCS also resulted in impaired intestinal transport by elevated ion flux and epithelial electrochemical gradient in fish fed LHUFA. Transcriptome pathway analysis indicated more cell turn over and lipid metabolism in LHUFA and HDHA. In conclusion, a low HUFA diet with 8.5 g/kg DHA + EPA can sustain growth and intestinal health under controlled condition, but the health is impaired after three weeks of chronic stress. Decreasing the n6/n3 ratio by increasing levels of EPA and DHA strengthens intestinal barrier in response to chronic stress. Increasing the ARA to HUFA ratio may have a negative effect on growth, but not on intestinal health.

Effects of different dietary lipid sources on fatty acid composition and gene expression in common carp

The effects of fatty acid composition in artificial feed on the change in the fatty acid composition of carp muscles and the relationship between Δ6-Fad and Elovl5 genes participating in the regulation of fatty acid synthesis were studied. Juveniles were fed three semi-purified diets (D1–D3) for 6 weeks with different lipid sources: D1, fish oil with high highly unsaturated fatty acids (HUFA); D2, corn oil with high linoleic acid (18:2n-6, LA), D3, linseed oil with high α-linolenic acid (18:3n-3, LNA); then, samples were taken to explore the molecular mechanism and the factors which affect the synthesis of carp HUFA. The content of LA and arachidonic acid (20:4n-6, AA) in common carp fed Diet 2 was higher than in carp receiving D3 (P &amp;lt; 0.05), but the contents of eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) were lower than in carp fed D1 and D2 (P &amp;lt; 0.05). The liver transcript abundance of Δ6-Fad and Elovl5 in fish fed D2 and D3 at the end of 6 weeks was generally higher than the abundance in the initial stage and in the fish fed D1 (P &amp;lt; 0.05). The results suggest that the common carp can biosynthesise HUFA, and the type and content of fatty acids in feed affected not only the composition and content of fatty acids in common carp muscles, but also the Δ6-Fad and Elovl5 gene expression involved in the biosynthesis of HUFA. Feeding high levels of n-3 HUFA diet can increase the body content of EPA and DHA in common carp. The results of this research may provide a theoretical basis for choosing an appropriate source of lipid for common carp feeds.

A comparison of the fatty acid profiles of newly hatched, fed, and starved juveniles of Amphioctopus fangsiao (d’Orbigny 1839)

The paper provides a first look into the fatty acids (FA) of young Amphioctopus fangsiao. Laboratory-hatched, 1-day-old juveniles (NH) were analyzed to identify the basal FA profile. To determine dietary effects on FA, individually kept juveniles (FD) were fed mysids once daily. Others were subjected to starvation (ST) to examine which FA may be used and which would be conserved. Treatments run for 25 days post-hatch, at which time ST and FD were analyzed to record FA changes. The dominant FA were 16:0, eicosapentaenoic (EPA), and docosahexaenoic (DHA), overall accounting for 40–60%. Monounsaturated FA (MUFA) were the highest in FD at 24.2% whereas highly unsaturated FA (HUFA) were most prominent in ST at 45.5%, followed by NH at 40.2%. Among n-3 HUFA, DHA was dominant in ST at 22.9 mg g−1 dry weight (DW), the role assumed by EPA in FD at 11.5 mg g−1 DW. Consequently, the DHA/EPA ratio was the lowest in FD. Arachidonic was the most abundant n-6 HUFA, representing >5% in total FA. However, n-6 FA were not prevalent, resulting in high n-3/n-6 in all juveniles. It could be argued that young A. fangsiao require n-3 HUFA, particularly DHA and EPA at a ratio of ideally >1.5 and to a lesser extent n-6 HUFA. Juveniles fed on a low lipid, high n-3 diet increased their MUFA content while maintaining high HUFA. Despite changes in the FA of ST individuals, it appears food-deprived A. fangsiao do not depend on FA mobilization for energy production.

The importance of dietary HUFA for meagre larvae (Argyrosomus regius; Asso, 1801) and its relation with antioxidant vitamins E and C

Despite the interest of meagre (Argyrosomus regius) as a fast-growing candidate for Mediterranean aquaculture diversification, there is a lack of information on nutrition along larval development. Importance of highly unsaturated fatty acids (HUFA) and the antioxidant vitamins E and vitamin C has not been investigated yet in this species. Six diets with two levels of HUFA (0.4% and 3% dw), two of vitamin E (1500 and 3000 mg kg−1) and two of vitamin C (1800 and 3600 mg kg−1) were fed to 15 dah meagre larvae. Larval growth in total length and dry body weight was significantly lowest in larvae fed diet 0.4/150/180 and showed few lipid droplets in enterocytes and hepatocytes and lower HUFA contents than the initial larvae. Increase in dietary HUFA up to 3%, significantly improved larval growth and lipid absorption and deposition. Besides, among fish fed 3% HUFA, increase in vitamin E and vitamin C significantly improved body weight, as well as total lipid, 22:6n-3 and n-3 fatty acids contents in the larvae. Thus, the results showed that 0.4% dietary HUFA is not enough to cover the essential fatty acid requirements of larval meagre and a high HUFA requirement in weaning diets is foreseen for this species. Besides, the results also pointed out the importance of dietary vitamin E and C to protect these essential fatty acids from oxidation, increase their contents in the larvae and promote growth, suggesting high vitamin E and C requirements in meagre larvae (higher than 1500 and 1800 mg kg−1 for vitamin E and vitamin C respectively).

Modelling the role of highly unsaturated fatty acids in planktonic food web processes: a mechanistic approach

Highly unsaturated fatty acids (HUFAs) are a subgroup of fatty acids characterized by chains of 20 or more carbon atoms with multiple double bonds, which potentially limit the growth of zooplankton. Zooplankton require high HUFA concentrations during periods of rapid growth, but co-limitation with nutrients is also likely to occur. Recent modelling results suggest food webs with high quality (nutritional and biochemical) primary producers can attain inverted biomass distributions with efficient energy transfer between trophic levels. In this study, our objective is to highlight the recent advances in studying the role of HUFAs in aquatic food webs. We take a first-principles approach to investigate the chemical nature of HUFAs, and the role they play in zooplankton ecology. To this end, we introduce a novel zooplankton growth sub model that tracks the interplay between nitrogen, phosphorus, and HUFAs in plankton population models. Our aim is to produce a sub model that incorporates the knowledge gained from decades of biochemical research into management-oriented predictive tools.

Influence of dietary fatty acids on muscle fatty acid composition and expression levels of Δ6 desaturase-like and Elovl5-like elongase in common carp (Cyprinus carpio var. Jian)

The effects of dietary fatty acids on muscle fatty acid composition and liver expression levels of Δ6 desaturase-like and Elovl5-like elongase were investigated in common carp (Cyprinus carpio var. Jian). Two Δ6 desaturase-like cDNAs (Fad6-a and Fad6-b) and two Elovl5-like elongase (Elovl5-a and Elovl5-b) cDNAs were cloned. Juvenile carp were fed three semi-purified diets (D1-3) for 6 weeks with different lipid sources: D1, fish oil with high highly unsaturated fatty acids (HUFAs); D2, corn oil with high linoleic acid (LA), but no HUFAs; and D3, linseed oil with high α-linolenic acid (LNA), but no HUFAs. Comparing muscle fatty acids among fish fed D1-3, the content of LA and arachidonic acid (AA) in common carp fed D2 and the content of LNA, EPA and DHA in common carp fed D3 were higher than initial levels (P<0.05), respectively. The liver transcript levels of Fad6-a and Elovl5-a in fish fed D2 and D3 were higher than initial levels (P<0.05), but Fad6-b and Elovl5-b levels were seldom affected by the diets. The dietary fatty acids affect the muscle fatty acid composition and the liver Fad6-a and Elovl5-a gene expression levels in common carp, and further studies should be undertaken.

High n-3 HUFA levels in the diet of Atlantic salmon affect muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress

Atlantic salmon were fed one of four diets with increasing levels (11–58%of total fatty acids (FAs)) of n-3 highly unsaturated FAs (HUFAs) in order to investigate the effect on muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress. The high n-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) groups contained lower percentages of sphingomyelin and cardiolipin in total muscle than the intermediate n-3 HUFA group. Cardiolipin and sphingomyelin are particularly susceptible to peroxidation, and a reduced percentage of these lipids showed that mitochondrial membranes had been damaged by oxidation. The intermediate n-3 HUFA group had the highest level of mitochondrial integrity and tendencies of lower thiobarbituric acid reactive substances (TBARS) level than the other dietary groups. The high caspase-3 activity, in addition to casp3a and bax gene expression levels, in the n-3 DHA group also suggests that some degree of oxidative stress had occurred. Electron microscopy images showed a higher degree of myofibre–myofibre detachment in fish fed the high HUFA diets than in fish fed the intermediate n-3 HUFA diet. Our findings show that intermediate levels of n-3 HUFAs in salmon diets gave the best protection against oxidative damage of mitochondrial membranes and muscle structure.

Effects of decontaminated fish oil or a fish and vegetable oil blend on persistent organic pollutant and fatty acid compositions in diet and flesh of Atlantic salmon (Salmo salar)

The health benefits of seafood are well documented and based on the unique supply of n-3 highly unsaturated fatty acids (HUFA). Aquaculture now contributes about 50 % of food-grade seafood globally and Atlantic salmon (Salmo salar) is a rich source of n-3 HUFA. However, salmon and other oily fish can accumulate lipophilic persistent organic pollutants (POP), including dioxins (PCDD/F), polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE), derived largely from feed. In the present study, triplicate groups of salmon, of initial weight 0.78 kg, were fed one of three experimental diets for 11 weeks. The diets were coated with either a northern fish oil (FO) with a high POP content (cNFO), the same oil that had been decontaminated (deNFO) or a blend of southern fish oil, rapeseed and soyabean oils (SFO/RO/SO). Dietary PCDD/F+dioxin-like PCB (DL-PCB) concentrations were 17.36, 0.45 and 0.53 ng toxic equivalents (TEQ)/kg, respectively. After 11 weeks, the flesh concentrations in fish fed the cNFO, deNFO and SFO/RO/SO diets were 6.42, 0.34 and 0.41 ng TEQ/kg, respectively. There were no differences in flesh EPA and DHA between fish fed the cNFO or deNFO diets although EPA and DHA were reduced by 50 and 30 %, respectively, in fish fed the SFO/RO/SO diet. Thus, decontaminated FO can be used to produce salmon high in n-3 HUFA and low in POP. Salmon produced using deNFO would be of high nutritional value and very low in POP and would utilise valuable fish oils that would otherwise be destroyed due to their high pollutant concentrations.

Fatty acid composition of juvenile abalone (Haliotis tuberculata coccinea) fed formulated diets containing various n3 HUFA levels

The effect of feeding different levels of n3 highly unsaturated fatty acids (HUFA) on the fatty acid profile was evaluated in soft tissue from juvenile Haliotis tuberculata coccinea. Five diets were formulated with different oil sources (palm, colza, fish, sunflower, and soybean), containing from 2.52% to 12.33% n3 HUFA, while fresh Ulva rigida was used as reference diet. The different diets were provided to groups of 20 abalone during 120 days in independent triplicates. Though no significant differences in growth (P &lt; 0.05) were registered among all formulated diets, a tendency to accumulate different fatty acids in muscle was observed. The proximate composition of abalone tissue showed that the diet containing 6.8% HUFA resulted in higher lipid accumulation in muscle tissue than that observed in the other treatments. Our results suggest that H. tuberculata coccinea, contrary to to abalone species from colder environments, does not have high HUFA requirements; however, the fatty acid profile of muscle and viscera tissues of abalone may be modulated by the fatty acid content in diets.

The effect of bacterivorous nematodes on detritus incorporation by macrofaunal detritivores: A study using stable isotope and fatty acid analyses

Several studies have investigated the effect of nematodes on microbial degradation of macrophyte detritus, but little is known about the potential effect of bacterivorous nematodes on productivity of macrofaunal detritivores. We investigated the influence of the bacterivorous nematode Rhabditis ( Pellioditis) mediterranea on the incorporation rate of isotopically-labelled macroalgal detritus by the amphipod Paramoera chevreuxi in a laboratory microcosm. The fatty acid composition of amphipods, nematodes, and macroalgal detritus was characterized to help determine the pathway of detritus incorporation by amphipods. The potential importance of R. mediterranea as a source of highly unsaturated fatty acids (HUFAs) to higher trophic levels was also investigated. We found no clear evidence for an effect of nematodes on the incorporation rate of fresh macroalgal detritus by amphipods, although there was some indication that the type of detritus (i.e. the green Chaetomorpha sp. vs the red Polysiphonia sp.) is important in determining the nature and extent of the relationship between nematodes and macrofaunal detritivores. Fatty acid data indicated that nematodes did not contribute significantly to the diet of amphipods when detritus was present, and there was no evidence that nematodes affected the pathway of detritus incorporation by amphipods. Amphipods incorporated Chaetomorpha sp. detritus about 10 times faster than Polysiphonia sp. detritus despite the higher C/N ratio and lower HUFA content of the former. This suggests that other factors, such as the presence of grazer deterrent compounds, are important in determining the palatability of macroalgal detritus. Amphipods fed exclusively on nematodes retained high HUFA levels but suffered high mortality. The burrowing behaviour of nematodes is suggested as the most likely factor limiting their availability to predators. Results suggest a limited interaction between amphipods and bacterivorous nematodes in detrital food webs. Further experiments are needed to test the wider applicability of these findings to different nematode and macrofaunal taxa, and for different types of detritus.

Influence of highly unsaturated fatty acids in live food on larviculture of mud crab Scylla paramamosain (Estampador 1949)

Two experiments were carried out to investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA) levels in rotifers (Brachionus plicatilis) and Artemia on the survival, development and metamorphosis of mud crab Scylla paramamosain larvae. Five different lipid emulsions, varying in the level of total n-3 and n-6 highly unsaturated fatty acids (HUFA), DHA, EPA and ARA were used to manipulate the fatty acid profile of the live food. Fatty acid profiles of the live food and crab larvae at zoea one, three and five stages were analysed to study the HUFA uptake by the larvae. The fatty acid content of the live food affected the fatty acid profiles of the crab larvae. In both experiments, the survival rate in the zoeal stages was not statistically different among treatments. However, larval development rate and metamorphosis success were affected by the dietary treatments. In this respect, the DHA/EPA ratio in the live food seems to be a key factor. Enrichment emulsions with a very high (50%) total HUFA content but a low DHA/EPA ratio (0.6), or zero total HUFA content caused developmental retardation and/or metamorphosis failure. An emulsion with a moderate total HUFA (30%) and a high DHA/EPA ratio (4) was the best in terms of larval development during the zoeal stages and resulted in improved metamorphosis. Dietary ARA seemed to improve first metamorphosis, but its exact role needs further clarification. For the larval rearing of S. paramamosain, an enrichment medium containing about 30% total n-3 HUFA with a minimum DHA/EPA ratio of 1 is recommended. Further investigation is needed on the total HUFA and optimum DHA/EPA ratio requirements for each crab larval stage.

Effect of hypo- and hyper-saline conditions on osmolarity and fatty acid composition of juvenile shrimp Litopenaeus vannamei (Boone, 1931) fed low- and high-HUFA diets

Litopenaeus vannamei (Boone) grown in ponds are exposed to salinities of less than 5 g L−1 during inland shrimp culture or to more than 40 g L−1 from evaporation and reduced water exchange in dry, hot climates. However, dietary requirements for shrimp grown in low or high salinities are not well defined, particularly for fatty acids. Feeding shrimp postlarvae with highly unsaturated fatty acids (HUFA) enhances tolerance to acute exposure to low salinity, as a result of better nutritional status, or/and specific effects of HUFA on membrane function and osmoregulation mechanisms. This study analysed the effect of HUFA supplementation (3% vs. 34%) on L. vannamei juveniles reared for 21 days at low (5 g L−1), medium (30 g L−1) and high salinities (50 g L−1). Juveniles grown at 5 g L−1 had lower survival compared with controls (30 g L−1) or shrimp grown at 50 g L−1, but no significant effect on survival was observed as a result of HUFA enrichment. In contrast, growth was significantly lower for shrimp grown at 50 g L−1, but this effect was compensated by the HUFA-enriched diet. Osmotic pressure in haemolymph was affected by salinity, but not by HUFA enrichment. Shrimp fed HUFA-enriched diets had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in hepatopancreas and gills. These results demonstrate that growth at high salinities is enhanced with diets containing high HUFA levels, but that HUFA-enriched diets have no effect on shrimp reared at low salinities.

Phospholipases as candidate genes in schizophrenia

Several studies have investigated the effect of nematodes on microbial degradation of macrophyte detritus, but little is known about the potential effect of bacterivorous nematodes on productivity of macrofaunal detritivores. We investigated the influence of the bacterivorous nematode Rhabditis (Pellioditis) mediterranea on the incorporation rate of isotopically-labelled macroalgal detritus by the amphipod Paramoera chevreuxi in a laboratory microcosm. The fatty acid composition of amphipods, nematodes, and macroalgal detritus was characterized to help determine the pathway of detritus incorporation by amphipods. The potential importance of R. mediterranea as a source of highly unsaturated fatty acids (HUFAs) to higher trophic levels was also investigated.We found no clear evidence for an effect of nematodes on the incorporation rate of fresh macroalgal detritus by amphipods, although there was some indication that the type of detritus (i.e. the green Chaetomorpha sp. vs the red Polysiphonia sp.) is important in determining the nature and extent of the relationship between nematodes and macrofaunal detritivores. Fatty acid data indicated that nematodes did not contribute significantly to the diet of amphipods when detritus was present, and there was no evidence that nematodes affected the pathway of detritus incorporation by amphipods. Amphipods incorporated Chaetomorpha sp. detritus about 10 times faster than Polysiphonia sp. detritus despite the higher C/N ratio and lower HUFA content of the former. This suggests that other factors, such as the presence of grazer deterrent compounds, are important in determining the palatability of macroalgal detritus. Amphipods fed exclusively on nematodes retained high HUFA levels but suffered high mortality. The burrowing behaviour of nematodes is suggested as the most likely factor limiting their availability to predators.Results suggest a limited interaction between amphipods and bacterivorous nematodes in detrital food webs. Further experiments are needed to test the wider applicability of these findings to different nematode and macrofaunal taxa, and for different types of detritus.

The role of highly unsaturated fatty acids in aquatic foodweb processes

1. Polyunsaturated fatty acids (PUFA) are almost exclusively synthesized by plants. Animals can convert from one form of PUFA to another through elongation and desaturation, but very few can synthesize PUFA de novo. PUFA play an important role in regulating cell membrane properties, serve as precursors for important animal hormones and are essential for animals.2. In aquaculture studies, highly unsaturated fatty acids (HUFA), a subset of PUFA, have been found to be critical for maintaining high growth, survival and reproductive rates and high food conversion efficiencies for a wide variety of marine and freshwater organisms.3. The plankton literature suggests high food‐quality algae species are rich in HUFA and low food‐quality algae are poor in HUFA. Adding semi‐pure emulsions of HUFA to algae monocultures can markedly increase the growth rates of zooplankton feeding on these mixtures.4. A study measuring zooplankton biomass accrual when feeding on natural phytoplankton found a strong correlation between phytoplankton HUFA (specifically eicosapentaenoic acid) content and herbivorous zooplankton production.5. The aquatic ecology literature suggests that planktonic foodwebs with high HUFA content phytoplankton have high zooplankton to phytoplankton biomass ratios, while systems with low HUFA phytoplankton have low zooplankton biomass. Also, the seasonal succession of plankton in many temperate lakes follows patterns tied to phytoplankton HUFA content, with intense zooplankton grazing and ‘clear‐water‐phases’ characteristic of periods when the phytoplankton is dominated by HUFA‐rich species.6. Herbivorous zooplankton production is constrained by the zooplankton’s ability to ingest and digest phytoplankton. It is becoming increasingly clear, however, that much of the phytoplankton which is assimilated may be nutritionally inadequate. HUFA may be key nutritional constituents of zooplankton diets, and may determine energetic efficiency across the plant–animal interface, secondary production and the strength of trophic coupling in aquatic pelagic foodwebs.

Influence of phospholipid and highly unsaturated fatty acids on spawning rate and egg and tissue composition in Penaeus vannamei fed semi-purified diets

In order to study the influence of dietary phospholipids (PL) and highly unsaturated fatty acids (HUFA) on spawning rate and egg and organ lipid composition of P. vannamei, three batches of eyestalk-ablated spawners were fed semi-purified diets for a period of 45 days. The semi-purified diets differed only in their lipid composition: diet HR had high HUFA and PL concentrations, diet HD had low HUFA and high PL concentrations, while diet PLD had low PL and HUFA concentrations. Control spawners were fed fresh mussel. The spawning rate of the PLD group was one-third of that obtained in the other three groups. Egg numbers per spawning were similar in groups fed the semi-purified diets but significantly inferior ( P<0.05) to the number observed in the control group. A large lipid deposition, mainly due to neutral lipid (NL), was observed in the hepatopancreas of animals fed semi-purified diets. The total lipid concentration of eggs did not significantly change with the different diets, but PL concentration of eggs was affected by that of diet. Fatty acid composition of both PL and NL of hepatopancreas, muscle and eggs was widely affected by dietary fatty acid composition. The time course variation of egg fatty acid composition during the feeding period notably showed that the HUFA concentration in eggs of HD and PLD groups fell below 2.5% dry matter after 20 days while it was maintained at up to 4% in eggs of the control group. The ability of eggs containing such a low level of HUFA to sustain lecitotrophic development is discussed with reference to previous studies.

Effects of Dietary Fatty Acid Enrichment on Survival, Growth, and Salinity-Stress-Test Performance of Inland Silversides

Abstract Larvae of inland silversides (Menidia beryllina) reared on three dietary levels of highly unsaturated fatty acids (HUFA) (low HUFA, medium HUFA, and high HUFA) showed no differences in survival or growth during a 3-week feeding trial and no differences in survival during a salinity stress test at 75‰. Inland silversides therefore appear to have dietary needs for (n-3) HUFA that are more like those of freshwater fish than marine fish, even though they are found in marine environments.