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It was evaluated the effect of DHA (extract from Aurantiochytrium sp.) inclusion in diets formulated with poultry by-product meal (PBM) using beef tallow (TALLOW) to fulfill the lipid demand in substitution of fish oil (FO) in juvenile totoaba (9.5 ± 0.1 g). With this purpose four diets were formulated to contain PBM with FO (PBM + FO positive control) or TALLOW (PBM + TALLOW negative control) and two diets containing different levels of DHA; one supplemented with 50% (PBM + TALLOW+50%DHA) and 100% DHA (PBM + TALLOW+100%DHA), based on DHA requirements for marine carnivore fish. After nine weeks, no signs of fatty acid (FA) deficiency were noticed; survival was above 92% across dietary treatments, and production performance was also similar, with exception of feed conversion ratio and viscerosomatic index. Tissues proximate composition was affected by dietary treatments. Tallow-based diets increased hepatic lipid content. However, 100% DHA supplementation adjusted this effect. Overall blood parameters were not influenced by tallow inclusion, except for triglycerides. Fish fed the PBM + TALLOW diet exhibited significant higher levels of triglycerides compared to those fed the PBM + FO diets. However, the DHA supplementation in both levels amended this effect. The FA profile in the liver and muscle tissues were affected and reflected the dietary fatty acid composition to some extent. Tallow-based diets exhibited significantly higher levels of MUFAs (e.g., 18:1n-9) and reduced levels of SFAs than those fed the PBM + FO control diet. Muscle tissue of fish fed the PBM + TALLOW diet exhibited significantly lower levels of DHA and EPA than that fed PBM + FO diet. However, DHA supplementation partially corrected this effect by enhancing DHA content in muscle. The magnitude of LC-PUFA “sparing effect” in the present study was limited due to the elevated levels of dietary 18:2n-6 from the PBM that accumulated in the muscle tissue in the extent of the LC-PUFAs. In summary, the current results provide valuable insights regarding dietary DHA in juvenile totoaba towards formulating fish oil-free diets. Dietary PBM and beef tallow successfully replaced FO in the context of production performance and overall blood parameters. DHA supplementation was beneficial for enhancing the levels of this human health-promoting fatty acid in the muscle tissue. Also, it might increase fish performance reducing the need of using fish oil in aquafeeds. We suggest that towards fish oil-free aquafeed formulations it is essential to balance the dietary fatty acids. Concomitant to this fact, it will be necessary to reduce the lipid content in PBM to facilitate feed formulation. [ABSTRACT FROM AUTHOR]

Diet-to-tissue transfer of long-chain polyunsaturated fatty acids (LC-PUFAs) is more efficient when diets contain saturated fatty acid (SFA) or monounsaturated fatty acid (MUFA)-rich alternative lipids. This mechanism, the omega-3 or LC-PUFA “sparing effect”, encourages more efficient metabolism of the limited LC-PUFAs available in terms of their important physiological functions and tissue retention, and the likelihood of successful fish oil sparing (i.e. complete fish oil replacement maintaining growth and tissue fatty acid profile). However, it is still unclear whether dietary SFAs and MUFAs are equivalent or interact synergistically or antagonistically in this context. Accordingly, we compared production performance and tissue fatty acid composition of California Yellowtail fed diets containing fish oil (rich in LC-PUFAs) or soybean oil (rich in C 18 PUFAs), partially hydrogenated soybean oil (rich in MUFAs), fully hydrogenated soybean oil (rich in SFAs), or blends of these soybean oils. After 10 weeks, production performance was not affected by dietary lipid source or fatty acid composition, and tissue fatty acid profiles generally mimicked dietary fatty acid composition. However, tissues of fish fed SFA-rich lipids exhibited the greatest similarity to those fed fish oil, and fillets of fish fed fully hydrogenated soybean oil had significantly higher levels of LC-PUFAs (43.9 g LC-PUFA /100 g fatty acid methyl esters; FAMEs) than those fed any of the other diets (22.5–36.9 g LC-PUFA /100 g FAMEs), including the LC-PUFA-rich fish oil-based feed (39.8 g LC-PUFA /100 g FAMEs). Power regression analyses demonstrated a stronger positive relationship between dietary SFAs with fillet LC-PUFA deposition ( r 2  = 0.73) than dietary MUFAs ( r 2  = 0.09), whereas dietary C 18 PUFAs were observed to have a negative relationship with fillet LC-PUFA content ( r 2  = 0.85). These trends were also observed in liver and eye tissues, and to a lesser extent in brain tissue. Multiple linear regression analyses demonstrated a stronger relationship between dietary levels of PUFAs and SFAs and tissue fatty acid profile composition, including LC-PUFA content, than dietary levels of PUFAs and MUFAs. Fillet lipid content varied significantly, with the FISH and C 18 PUFA SOY diets displaying the highest levels. The same pattern was observed for liver lipid content, but not significantly. Our findings suggest that SFAs are the primary drivers of LC-PUFA sparing, whereas MUFAs exert a weaker independent sparing effect and appear to diminish the sparing effect of dietary SFAs when MUFAs were also present. [ABSTRACT FROM AUTHOR]

Abstract: The fatty acid reserves of broodstocks profoundly affect the fecundity of spawners as well as the quality of the newly hatched larvae. Investigation of the lipid and fatty acid changes in wild-caught broodstocks during the reproductive season should elucidate the most effective strategy with which to enrich broodstocks in artificial breeding programs. This paper investigated the lipid and fatty acid compositions of wild broodstocks of silver pomfret, Pampus argenteus, caught at the Zhoushan fishery ground during the reproductive season. The results indicated that there were significant differences in lipid content among gonad, muscle and liver; mean lipid levels in ovary, testis, liver and muscle were 41.85%, 18.54%, 27.80% and 32.31%, respectively. The lipid content in gonads at developmental stages III–V was relatively more stable than that in muscle or liver, although the lipid level increased in ovary and decreased in muscle as the female broodstocks developed from phase III to phase V. There were significant differences in fatty acid levels among broodstock ovary, testis, muscle and liver. The dominant fatty acids in ovary were as follows: 18:1n−9 (16.91%)>DHA (docosahexaenoic acid) (15.46%)>16:4n−3 (13.14%)>16:0 (12.65%)>EPA (eicosapentaenoic acid) (6.46%)>16:1 (5.34%). In female broodstock liver and muscle, the dominant fatty acids were 16:0 (36.42%)>18:1n−9 (23.26%)>18:0 (7.50%)>16:1 (6.98%)>14:0 (5.10%)>DHA (4.98%) and 18:1n−9 (26.35%)>16:0 (24.07%)>DHA (8.38%)>16:1 (6.62%)>18:0 (5.48%)>14:0(4.44%), respectively. The dominant fatty acids in testis were as follows: DHA (29.84%)>16:0 (23.93%)>18:1n−9 (8.78%)>18:0 (7.98%)>EPA (7.96%)>ARA (arachidonic acid) (3.24%). In the liver and muscle of male broodstocks, the dominant fatty acids were 16:0 (30.14%)>18:1n−9 (25.54%)>18:0 (8.24%)>16:1 (7.24%)>14:0 (5.20%)>DHA (4.75%) and 18:1n−9 (29.51%)>16:0 (23.90%)>DHA (7.80%)>18:0 (6.34%)>16:1 (6.22%)>14:0(3.88%), respectively. The n−3PUFAs and n−3/n−6 ratios in ovary and testis of the broodstocks were significant higher than those in the liver and muscle of the broodstocks. The changes in fatty acid composition in ovary and testis as the broodstocks developed from phase III to phase V were smaller in magnitude than those in muscle or liver. It is therefore suggested that the lipid preferentially transferred to ovary from muscle during the reproductive season, and the PUFAs, such as DHA, EPA, 16:4n−3 and ARA, were selectively transferred to, and conserved in, the ovaries of silver pomfret broodstocks. [Copyright &y& Elsevier]

Abstract: The biochemical composition of eggs and the nutrient dynamics during early ontogeny can provide better understanding on the nutritional requirements of both broodstock and first-feeding fish, thus constituting a valuable tool for improvement of aquaculture procedures. This study constitutes the first record of lipid composition and fatty acid dynamics during early development of seahorses. Lipid content and fatty acid profile were determined for Hippocampus guttulatus eggs and newborn juveniles, and their patterns of consumption were analyzed during embryonic development. H. guttulatus produced small broods (426±128 juveniles) but invested in the production of large eggs (2.44±0.37mm) that resulted in large fingerlings (15.53±1.28mm), which may have a high survival capacity. The total lipid content of seahorse eggs (17.6% DW) was within the typical range of marine fish eggs. Eggs were dominated by PUFA (43.9%), mainly n−3 HUFA (17.4% of DHA and 13.2% of EPA), and showed a lower MUFA content (22.5%). Extremely low AA levels (0.6%) and particularly high EPA concentrations resulted in a low DHA:EPA ratio (1.3) and high EPA:AA (22.3) and n−3:n−6 (12.2) ratios. Fatty acid consumption during embryonic development was considerably high (67.8%), reflecting the high requirements of seahorse embryos. Fatty acids were depleted at different rates, with PUFA being preferentially consumed (75.2%), while SFA were selectively retained (59.2%). PUFA constituted the major source of metabolic energy and the fatty acids 16:0, EPA and DHA were the main fatty acids to fulfill the energetic demands of seahorse embryos. Essential fatty acids (AA, EPA and DHA) were not preferentially retained, with EPA being catabolized at a particularly high rate (88.0%). These patterns of embryonic consumption resulted in newborn juveniles with an exceptionally low lipid content (5.0% DW), a predominance of SFA (41.0%) and extremely low EPA levels (5.0%). Fatty acid composition of H. guttulatus eggs and juveniles provided important clues to determine seahorse requirements, so that suitable feeding protocols could be developed. The use of broodstock and juvenile diets that reflect the lipid profile of eggs will allow the accomplishment of nutritional requirements and improvement of seahorse production. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to investigate how different dietary lipid levels affect growth, liver lipid deposition, apparent digestibility, apparent retention and utilization of total lipid and fatty acids in Atlantic cod. Individually tagged cod, with an average weight of 360 g, were randomly distributed in nine tanks, 49 fish per tank. Five diets with increasing dietary lipid level in the range of 80 to 268 g kg−1 were fed to the fish for 85 days, in a regression design. Increasing dietary lipid level did not affect growth of Atlantic cod, but the hepatic somatic index (HSI) increased from 7.5 to 11.8%. The liver lipid level increased from 719 to 785 g kg−1, constituting from 83 to 88% of total body lipid. Apparent lipid digestibility had an optimum level at a dietary lipid content between 138 and 180 g lipid kg−1 diet with a marked decrease at lipid levels above 180 g kg−1. Digestibility of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) responded similar to that of total lipid, while digestibility of the n−3 fatty acids increased with increasing dietary lipid level. Apparent retention of fatty acids increased with increasing dietary lipid level, except for 18:0 and 18:1n−9. Apparent retention of 14:0 and 16:0 was low (0–60%), while the retention of 18:0 was high (150–200%), indicating that cod may elongate 14:0 and 16:0 to 18:0 and also utilize these fatty acids for energy production, particularly in low lipid diets. The low apparent retention of long MUFAs indicated that they were used for energy production. Apparent retentions of 22:6n−3 and 20:5n−3 were intermediate (50–80%) at low dietary lipid inclusion, but increased with increasing lipid level, indicating that also these essential fatty acids may have been utilized for energy production, especially in low lipid diets. [Copyright &y& Elsevier]

Abstract: The effects of different dietary lipids (hydrogenated coconut oil, corn oil, linseed oil, and mixtures of corn oil, linseed oil, menhaden oil, and/or soy lecithin) on the fatty acid composition of the sea urchin Strongylocentrotus droebachiensis were investigated. Dietary lipid compositions were reflected in the fatty acid profiles of sea urchin guts, gonads and shells. The shells had the highest level of 20:4n-6 and 20:5n-3, while the highest levels of monounsaturated fatty acids were seen in the guts. Tissue levels of 20:4n-6 and 20:5n-3 were influenced by the dietary levels of 18:2n-6 and 18:3n-3. The addition of soy lecithin to the diet (CLnML) enhanced the production and incorporation of 20:4n-6 in shell and gonad. Sea urchin also synthesized and incorporated 20 and 22 carbon non-methylene-interrupted dienoic fatty acids (NMIDs) in all tissue lipids. The NMID content varied among the different tissues and was influenced by the dietary lipid source. The hydrogenated coconut oil (HCO) diet resulted in the greatest NMID content, while the lowest levels were seen in sea urchins fed diets containing a mixture of corn oil, linseed oil, menhaden oil and lecithin (CLnML). The NMID content was lowest in gut and highest in the shell. Significant levels of mead acid (20:3n-9) were detected in the shells of sea urchins fed the EFA-deficient diet (HCO). The enzymatic capabilities of sea urchins to desaturate and elongate 18:2n-6 to 20:4n-6 and 18:3n-3 to 20:5n-3, as well as the capabilities to de novo synthesize NMID were hypothesized. Possible physiological roles and mechanisms for formation of NMID are discussed. [Copyright &y& Elsevier]

The lipid class and the fatty acid composition of microalgae are of primary importance in feeding filter-feeding animals properly and variations of those parameters have never been investigated in a cultivation system applied to hatcheries. The objective of this study was to document the lipid class and fatty acid composition of the diatom Chaetoceros muelleri (CHGRA) and the flagellate Isochrysis sp. (Clone TISO) during the entire process of hatchery cultivation in relation to the period of the year (summer vs. winter). At the beginning of the cultivation process of CHGRA, in a small volume of culture, triacylglycerol (TAG), sterol, saturated, monounsaturated, and polyunsaturated fatty acids (particularly 20:5n−3) were high, sharply dropping when volume was increased. An inverse relationship has been observed for acetone mobile polar lipids (AMPLs; pigment) and phospholipids (PLs), thus leading to no significant effect of the volume of culture on the total lipid (TL) content of CHGRA. The total lipid content of TISO increased with the volume of culture due to AMPL and PL classes and saturated and polyunsaturated fatty acids. The short- and long-term variability of lipid class composition has been observed for both species. Such results highlight the high variability of marine microalgae lipid content during the culture process and season as well. Hatchery implication is discussed. [Copyright &y& Elsevier]