Fillet Fatty Acid Research Articles

Modelling changes in whole body and fillet fatty acid composition of Atlantic salmon with changing levels of dietary omega-3 intake

In this study, a fatty acid dilution model was coupled with a dynamic nutrient demand model to provide an integrated model capable of predicting the whole-body and fillet lipid and fatty acid levels of Atlantic salmon (Salmo salar) following a change in dietary fatty acid profile. Based on knowledge of the initial fish and dietary fatty acid compositions, diet digestible energy density, the water temperature and duration of feeding, the model demonstrated that it was possible to predict a range of parameters, including the growth, feed utilisation, whole-body and fillet (Norwegian Quality Cut; NQC) total lipid, and fatty acid levels of the fish. The model was validated against five separate experiments, including two farm-based trials with harvest size fish. Validation experiments involved fish ranging in size (initial weights to final weights) from 138 g/fish to 5138 g/fish and running for durations of between 66 and 323 days. For the laboratory experiments, prediction of growth, feed utilisation and fatty acid deposition proved to be highly predictable (R2 > 0.998). Fatty acid profiles from both short and long-term cage trials were also highly predictable. Despite the reduced level of weight change in the short-term cage trial, and the higher variability that was observed in growth performance, the fatty acid deposition still showed high levels of correlation (R2 > 0.996), between the modelled and measured fatty acid levels in the fish fillet. Departure from linearity was more evident in the long-term cage trial, but correlation still exceeded R2 > 0.995 for all treatments. Prediction of whole-body and NQC total lipid levels was less accurate, with correlations being R2 = 0.962 and R2 = 0.909 respectively. Model outputs were generally more accurate with greater weight change and/or experiment duration. The outcome of this study shows that the model developed here provides a useful tool for the estimation of the fatty acid composition of Atlantic salmon following a change in dietary fatty acid composition. This could help assist in the more judicious use of dietary long-chain omega-3 fatty acids for commercial salmon farming.

Growth, Hepatic Enzymatic Activity, and Quality of European Seabass Fed on Hermetia illucens and Poultry By-Product Meal in a Commercial Farm.

Protein meals from insects in combination with poultry by-product meal appear to be promising ingredients for replacing conventional proteins in the diets of carnivorous fish. The present study explored the effects on growth performance, hepatic enzymatic activity, and fillet physical and nutritional characteristics during a 66-day feeding trial performed on European seabass. A total of 3000 fish were distributed into three tanks, where the control group was fed with a commercial diet (CG) and a second group was fed in duplicate with the experimental diet (SSH) containing 10% Hermetia illucens larva meal, 30% poultry by-product meal, and <5.5 g/100 g of feed of marine origin proteins. All fish showed good growth performance. Glucose-6-phosphate dehydrogenase, aspartate aminotransferase, and 3-hydroxyacyl-CoA dehydrogenase activities were higher in the SSH group than in the CG group. The fillet fatty acid profile was largely unaffected by diet, except for a few fatty acids. Fish fed the SSH diet had a lower C22:1n-11 content than CG, thus suggesting an increased β-oxidation. The oxidative status of muscle lipids was not affected by the diet. In conclusion, the present study showed that European seabass can be successfully fed the SSH diet for two months in a commercial setting.

Impairment on fillet fatty acid profile and oxidative damage in pirarucu, Arapaima gigas, acutely exposed to extreme ambient temperature

Climatic events are affecting the Amazon basin and according to projections it is predicted the intensification of climate changes through increases in temperature and carbon dioxide (CO2). Recent evidence has revealed that exposure to an extreme climate scenario elicits oxidative damage in some fish species, impairing their metabolism and physiology, contributing to their susceptibility. Thus, the comprehension of physiological alterations in Arapaima gigas (pirarucu) to the climatic changes forecasted for the next 100 years is important to evaluate its capability to deal with oxidative stress. The objective of this work was to determine whether antioxidant defense system is able to prevent muscle oxidative damage of pirarucu exposed 96 h to extreme climate scenario, as well as the effects of this exposition on muscle fatty acid levels. Lipid peroxidation and reactive oxygen species significantly increase in the muscle of pirarucus exposed to an extreme climate scenario compared to control, while muscle superoxide dismutase, catalase, and glutathione peroxidase were significantly lower. Total amount of saturated fatty acids (SFAs) was significantly higher in pirarucu exposed to an extreme climate scenario compared to control, while total content of monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) was significantly lower. Exposure to an extreme climate scenario causes muscular oxidative stress and that the antioxidant systems are inefficient to avoid oxidative damage. In addition, the increase of total SFAs and the decrease of MUFAs and PUFAs probably intend to maintain membrane fluidity while facing high temperature and CO2 levels.

Influence of Krill Meal on the Performance of Post-Smolt Atlantic Salmon That Are Fed Plant-Based and Animal-Based Fishmeal and Fish Oil-Free Diets

The purpose of this study was to determine the influence of krill meal (KM) inclusion at various levels (0%, 2.5%, 5%) in plant-based and animal-based feeds, that were fishmeal (FM) and fish oil (FO) free, on Atlantic salmon growth. A FM/FO feed containing 0% KM was the control. Using a 2 × 3 factorial approach, diets were randomly assigned to one of 28 0.5 m3 flow-through tanks (n = 4 tanks per diet) initially stocked with 60 fish (148.4 ± 12.9 g; 23.6 ± 0.8 cm; condition factor (K) = 1.16 ± 0.08) each. Salmon were fed for 90 days using automatic feeders ad libitum. On day 45, stocking densities were reduced to 45 fish per tank by the random removal of 15 individuals to remove any potential of density affecting growth through the trial end. Water temperature, oxygen saturation, pH, and salinity throughout the trial were 11.8 °C, 103.5%, 7.38, and 32.0 g L−1, respectively. Fish fed plant-based feed without KM were lighter (p &lt; 0.05) than all other groups at day 45 and 90, but those fed a plant-based feed with KM had comparable growth and feed intake compared to that of fish fed the control diet. Irrespective of the presence of KM, animal-based feeds achieved comparable weight growth (p &gt; 0.05) to the control and 5% KM plant-based groups, with KM increasing feed intake (p &lt; 0.05). Between day 45 and 90, feed conversion ratios increased in all groups except the control and 0% KM plant-based group, while specific growth rates (SGRs) decreased for all except the 0% KM plant-based diet. Between-group differences (p &lt; 0.05) were also noted for the thermal growth coefficient. No differences were recorded in visceral or intestinal weight, and whole-body lipid levels were identical, proportional for all groups. Although differences (p &lt; 0.05) were apparent in the concentrations of individual fillet fatty acids between groups, a 75 g serving size of any treatment would be sufficient to exceed daily intake recommendations for EPA + DHA. This trial determined that benefit, in terms of feed intake and growth performance, was gained when KM was added to plant-based feeds. However, no such advantage was observed when KM was used with animal-based feeds.

Rate of change in the fillet fatty acid profile of Nile tilapia to attain a nutraceutical level of DHA + EPA for human consumption

Nile tilapia, Oreochromis niloticus, grows adequately in the absence of dietary omega-3 long-chained polyunsaturated fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid. However, its fatty acid profile can be enriched by feeding finishing diets for some time before harvesting, to reach a desirable content of 250 mg of DHA + EPA in a 100 g fillet, recommended as the daily intake of these essential fatty acids for human consumption by the Food and Agriculture Organization of the United Nations, thus improving its economic and nutritional value as a nutraceutical. The objective of this study was to evaluate the rate of change in the fatty acid profile of tilapia's fillet by feeding diets formulated with soy (SO) or fish oil (FO) in an 8-week bioassay, with two additional treatments, feeding FO for four weeks followed by SO for four additional weeks (FO/SO), or the opposite treatment (SO/FO). No significant differences among treatments were observed at the end of the study for growth performance (weight gain: 103.28–115.83 g; specific growth rate: 6.60–6.83% day−1; daily weight gain: 1.95–2.19 g day−1; survival: 96.67–100%), feed efficiency (1.16–1.31), body indices (hepatosomatic index: 1.48–1.89%; condition factor, K: 2.25–2.43), or proximate composition of the fillet, confirming the versatility of tilapia to efficiently use lipid sources of different nature. However, the fatty acid profile of the dietary lipid source directly influenced the fatty acid profile of the fillet; it was confirmed that, under these experimental conditions, it is possible to enrich the fillet of O. niloticus and reach the concentration of 250 mg of DHA + EPA in a 100 g fillet in just 10 days, for fish of the experimental size (3.11 g of individual initial weight) used in this study and under the prevailing experimental conditions.

Effects of black soldier fly (Hermetia illucens) larvae oil on fillet quality and nutritional traits of gilthead seabream

A study was conducted to evaluate the effects of dietary inclusion of black soldier fly (Hermetia illucens) larvae oil (HIO) on fillet fatty acid (FA) profiles and other nutritional traits of gilthead seabream (Sparus aurata). Four experimental diets were formulated with 45% crude protein and 18% lipids (circa 50:50 of fish oil and vegetable oil (VO) blend: 20% rapeseed, 30% palm, and 50% linseed oil) and HIO was used to replace VO blend at 42%, 84%, and 100%, corresponding to a dietary inclusion level of 4%, 7.9%, and 9.5%, respectively. After a feeding trial of 10 weeks, several fillet quality traits were analyzed, including morphometric and somatometric indexes, physical and chemical characteristics, FA profile, and lipid peroxidation products. No differences were found in the morphometric and somatometric parameters, or skin and fillet color. The fillets FA profile was significantly modulated by the experimental diets, showing an increase in saturated fatty acids (SFA), particularly lauric acid, and a decrease in monosaturated FA and n-3 and n-6 polyunsaturated fatty acids (PUFA) with the increase of HIO inclusion, while eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents were not affected. Fillets FA quality indexes (PUFA/SFA, n-3/n-6 PUFA ratio, hypocholesterolemic/hypercholesterolemic ratio, thrombogenicity, and atherogenicity indexes) were also modulated by dietary HIO inclusion. Fillets pH was reduced and water holding capacity increased with dietary HIO inclusion. Fillet lipid peroxidation level (measured as TBARS) was significantly decreased with dietary HIO inclusion despite an increase in conjugated dienes. Overall, results showed that HIO can efficiently replace VO in gilthead seabream diets, without major negative effects on fillet characteristics and quality traits while decreasing fillet lipid oxidation.

Evaluating a microalga (Schizochytrium sp.) as an alternative to fish oil in fish-free feeds for sablefish (Anoplopoma fimbria)

Alternative feeds are critical for the sustainable expansion of the marine finfish aquaculture industry. The industry uses wild-caught forage fish as a primary ingredient in farmed fish feeds. Alternative ingredients are needed to safeguard fisheries' sustainability and future aquaculture development. While there have been successes in alternative feeds, it is necessary to improve the existing options and identify alternative ingredients with higher concentrations of omega-3 polyunsaturated fatty acids (PUFAs). This study was designed to test a microalga, Schizochytrium sp., as a feed ingredient for sablefish (Anoplopoma fimbria) using six test diets. There were two fish-ingredient control diets: +FM+FO, which contained both fishmeal and fish oil, and −FM+FO, which contained fish oil, but no fishmeal. The remaining four diets contained alternative lipids and were completely fish-free. FF Flax contained flax oil as the only lipid source replacing fish oil. FF LowSc, FF ModSc, and FF HighSc contained a low, moderate, and high level of Schizochytrium sp. to replace fish oil, with flax oil content decreasing as the microalga increased. After a 20-week trial, sablefish growth differed across the feed treatments, with fish fed the high microalga-inclusion diet (FF HighSc) performing similarly to fish fed the fish-ingredient controls. Fulton's K condition factor, dry feed intake (DFI), and lipid productive value (LPV) were also influenced by treatment. For the four fish-free diets, specific growth rate increased with increasing inclusion of Schizochytrium sp. in the feed. Fillet fatty acid profiles were similarly influenced by diet treatment, generally reflecting the fatty acid profiles of the feed. Total fillet PUFAs were higher in sablefish from the fish-free treatments than the control treatments, with DHA increasing with increasing inclusion of dietary Schizochytrium. In contrast, EPA was higher in fillets from both fish-ingredient control treatments compared to fillets from the fish-free treatments, yet EPA remained higher than expected in sablefish fed the fish-free diets. Histologic evaluation of sablefish distal intestine and liver demonstrated that the microalga-inclusion diets were well tolerated and did not cause histomorphological changes in the tissues. These results suggest Schizochytrium sp. can increase PUFA concentrations in fish fillets without compromising fish health and growth, making it a viable ingredient for alternative sablefish feeds.

Partial and full replacement of dietary fish oil by poultry fat feeds in rainbow trout, Oncorhynchus mykiss

ABSTRACT The study investigated the effects of dietary fish oil replacement by poultry fat on growth performance, fillet quality, and serum enzymatic activities in rainbow trout, Oncorhynchus mykiss. The fish were fed three diets (0%, 50%, and 100% replacement) for 2 months with or without a washout period. No significant effects were observed among treatments on growth performance and viscerosomatic index or on fillet moisture, fat, protein, and ash contents (p > .05). Increased poultry fat led to decrease in ω-3 fatty acids and increase in ω-6 fatty acids and monounsaturated fatty acids. The washout period restored most of the changes in fillet fatty acid profiles and serum enzymatic activity in the fish feed containing poultry fat. In conclusion, replacement of dietary fish oil by poultry fat had no detrimental effects on fish growth performance, but reduced fish fillet ω-3 fatty acids, which can be restored via a washout period.

Enhancing Rearing of European Seabass (Dicentrarchus labrax) in Aquaponic Systems: Investigating the Effects of Enriched Black Soldier Fly (Hermetia illucens) Prepupae Meal on Fish Welfare and Quality Traits.

Within the modern aquaculture goals, the present study aimed to couple sustainable aquafeed formulation and culturing systems. Two experimental diets characterized by 3 and 20% of fish meal replacement with full-fat spirulina-enriched black soldier fly (Hermetia illucens) prepupae meal (HPM3 and HPM20, respectively) were tested on European seabass (Dicentrarchus labrax) juveniles during a 90-day feeding trial performed in aquaponic systems. The experimental diets ensured 100% survival and proper zootechnical performance. No behavioral alterations were evidenced in fish. Histological and molecular analyses did not reveal structural alterations and signs of inflammation at the intestinal level, highlighting the beneficial role on gut health of bioactive molecules typical of HPM or derived from the enriching procedure of insects' growth substrate with spirulina. Considering the quality traits, the tested experimental diets did not negatively alter the fillet's fatty acid profile and did not compromise the fillet's physical features. In addition, the results highlighted a possible role of spirulina-enriched HPM in preserving the fillet from lipid oxidation. Taken together, these results corroborate the use of sustainable ingredients (spirulina-enriched HPM) in aquaponic systems for euryhaline fish rearing.

Different Diets Based on Yellow Mealworm (Tenebrio molitor)—Part A: Facing the Decrease in Omega−3 Fatty Acids in Fillets of Rainbow Trout (Oncorhynchus mykiss)

Aquaculture struggles with sustainability due to the use of fishmeal, and insects are one potential alternative. Insects have low long-chain omega−3 polyunsaturated fatty acid content, and insect-fed fish reflect this in their composition. In total, 500 rainbow trout (Oncorhynchus mykiss, ~46 g) were fed until the fish reached a commercial size (~415 g). Five diets were used: one control based on fishmeal as main source of protein; two with a 50% replacement of fishmeal with yellow mealworm meal (Tenebrio molitor), one with full-fat insect, and another partially defatted; two other diets similar to the one with the full-fat insect, but with the addition of an experimental algal oil rich in omega−3 in two different concentrations (one equivalent to control, the other one to the defatted insect diet). Growth was unaffected, as well as texture and organoleptic profile of the fillets. Lightness, brightness and colour of the fillets were slightly modified by the experimental diets. An increase in omega−3 levels over those of the full-fat insect diet is described. An omega−3 sparing effect was highlighted, causing lipid accumulation in fillets and liver, and a mild increase in oxidative damage. More research is encouraged to evaluate the fatty acid profile of the liver.

Dietary inclusion of oregano essential oil in rainbow trout (Oncorhynchus mykiss) diet: effect on growth performance, skin and intestinal morphology, antioxidant status, and fillet fatty acid profile

Dietary inclusion of oregano essential oil in rainbow trout (Oncorhynchus mykiss) diet: effect on growth performance, skin and intestinal morphology, antioxidant status, and fillet fatty acid profile

Substituting palm oil for fish oil in feeds for juvenile rohu, Labeo rohita: effects on growth performance, fillet fatty acid composition, and antioxidant capacity

Substituting palm oil for fish oil in feeds for juvenile rohu, Labeo rohita: effects on growth performance, fillet fatty acid composition, and antioxidant capacity

Assessment of open‐source fish‐free feeds ( F3 ) for pompano, Trachinotus carolinus (Perciformes, Carangidae), under hyposaline conditions

Florida pompanos (15.3 g initial average weight) were fed one of seven open-source experimental diets to examine the effects of the complete removal of fishmeal (FM) and fish oil (FO) upon growth over a 12-week period. Diets were compared against an investigational feed containing FM and FO. Three different oils, derived from flax, canola and an alga, alone or in combination, were evaluated as alternatives for FO. FM was replaced in the experimental diets using a blend of proteins that included poultry by-product meal, hydrolysed soy and soy and corn protein concentrates. The study was undertaken in a recirculating aquaculture system and under hyposaline (3 g/L) conditions with each diet being examined in triplicate. At trial end, fish fed some diets increased their initial body weight by over 300%, and there were no differences (p > 0.05) between diets for feed efficiency, condition or K-factor, whole-body composition, intraperitoneal fat (%), hepatosomatic index or fillet yield (%). All experimental diets achieved parity with the FM/FO control feed. Differences were detected in fillet fatty acids among diets, with the latter corresponding to dietary profiles. This study represents the first with pompano to evaluate diets simultaneously void of FM and FO and provides strong evidence to support the practicability of removing FM/FO from pompano diets.

Evaluation of nutritional quality and fatty acid profile of carp (Cyprinus carpio) fed with diet based on oil sources

Background: The Cyprinus carpio as commercial fish in Iran contains nutritive components and plays an important role in human health. The present study research evaluated the nutritive quality of carp including proximate and fatty acid compositions. Objective: The aim of the present study was to investigate the effects of diet based on oil sources on the fatty acids composition of fish fillets of Cyprinus carpio. Methods: The carp (Cyprinus carpio) were fed with four diets based on soybean oil (SO), palm oil (PO), fish oil (FO), and (soybean and palm) oil (SPO). Results: The quality of fatty acids in the body of fish fed with SO and PO diets was found significantly better (p &lt;0.05) than those fish fed with FO diet. Total SFA (Saturated fatty acids) was highest significant in the fillet fat of the carp fish fed with PO diet, but there were no significant differences between the MUFA (Mono unsaturated fatty acids), PUFA (Poly unsaturated fatty acids), HUFA (High unsaturated fatty acids), and n-3/n-6 fatty acids of fillet in the carp fish fed with the experimental diets. Fillet fatty acid composition reflected dietary fatty acid profile. The highest level of α-linolenic acid, linoleic acid, and oleic acid was observed in fish fillets fed FO and SO, respectively. Although the eicosapentaenoic acid level of fish fillets fed diets FO and SPO was higher than other treatments, no significant difference was found in docosahexaenoic acid content among all dietary treatments. Conclusion: The present study showed that the suitable diet fat sources (SO, PO, SPO) fed by the carp, Cyprinus carpio, for 56 days, was suitable their productivity.

Influence of dietary Plukenetia conophora seed on growth performance, hepatic antioxidant status, blood chemistry, fillet quality, fatty acid, and oxidative stability of Clarias gariepinus

This study assessed the effects of dietary supplementation of Plukenetia conophora seed (PCS) on growth performance, blood chemistry, hepatic antioxidant status, fillet fatty acids, and physicochemical properties of Clarias gariepinus. Two hundred and seventy post-juvenile Clarias gariepinus (14.2 ± 1.4 g, BW) were randomly assigned to either T1, a control diet without PCS; T2, diet containing 2.5% PCS; or T3, diet containing 5% PCS, and were fed the different diets for 70 d. Each treatment consisted of six replicates with 15 fish per replicate. Diet had no effect (P > 0.05) on feed intake, hepatosomatic index, viscerosomatic index and survival rate of C. gariepinus. Body weight gain and specific growth rate increased (P < 0.05) as the level of PCS increased in diet. The T3 C. gariepinus had lower (P < 0.05) feed conversion ratio compared with the control C. gariepinus. Leucocytes, serum LDL-cholesterol and total cholesterol were higher (P < 0.05) in the control C. gariepinus compared with the T2 and T3 C. gariepinus. Hepatic glutathione peroxidase, superoxide dismutase, and catalase increased (P < 0.05) with increase in PCS levels in diet. Hepatic glutathione S-transferase was higher (P < 0.05) in the control C. gariepinus compared with the supplemented C. gariepinus. The percentage of C18:3n-3, C22:5n3 and C22:6n-3 was higher (P < 0.05) while that of C18:2n-6 and C20:4n-6 was lower (P < 0.05) in the fillet of C. gariepinus fed on 2.5% and 5% PCS compared with the control C. gariepinus. Dietary PCS had no effect on fillet pH, chemical composition, carbonyl concentration, water holding capacity, color coordinates, and TBARS values in C. gariepinus. These results evince that dietary inclusion of PCS enhanced fillet n-3 polyunsaturated fatty acids and growth performance without instigating fillet oxidative spoilage in C. gariepinus.

Replacement of Fish Oil by ALA‐Rich Vegetable Oils in Diets of Gilthead Sea Bream: Effect on Final Eating Quality

AbstractThis study assesses the effect of inclusion of n–3 C18 rich oils on nutrient profile and quality of flesh in gilthead seabream (≈ 61.5 g) after feeding isoproteic and isolipidic diets in which camelina seed (CSO) or chia oil (CO) totally or partially replaces fish oil (FO) for 110 days. Fillet fatty acid (FA) profile reflects dietary FA profile, characterized by increased C18 polyunsaturated FA (PUFA) and a reduced highly unsaturated FA, whereas n–3/n–6 ratios are increased in fish fed diets with CSO or CO content. However, indices of atherogenicity and thrombogenicity, calculated from the fillet FA profile as indices for the health quality for consumers, are reduced with dietary addition of CSO or CO due to the increased fillet content of C18 n–3 PUFA in CSO and CO fed fish. In spite of the differences in fillet FA profiles, sensory quality of flesh does not vary among fish from different dietary groups. Instrumental texture and color analyses reveal significantly different values in cooked fillets in comparison to the raw fillets. Overall, dietary inclusion of CSO or CO enhances the nutritional value of fish flesh as well as the production of healthier fillets.Practical Applications: This study suggests fish oil could be totally replaced with camelina or chia oil in the diet of gilthead sea bream without negatively affecting sensory characteristics. The dietary inclusion of these oils could enhance the nutritional quality of fish fillets, and could receive wide application in the aquafeed and animal feed producing sector.

Effects of fasting and temperature on the biological parameters, proximal composition, and fatty acid profile of Chinook salmon (Oncorhynchus tshawytscha) at different life stages

We investigated the effects of temperature and fasting on chinook salmon (Oncorhynchus tshawytscha) at different life stages. In the first stage, fish were reared at 13 °C (198.5 ± 34.6 g) or 17 °C (218.3 ± 47.6 g) and fasted for 27 and 26 days, respectively. In the second stage, fish reared at 13 °C (481.8 ± 54.3 g) and 17 °C (597.3 ± 64.3 g) were fasted for 42 and 41 days respectively. At the third stage, fish were reared only at 17 °C (1065.7 ± 190.9 g) and fasted for 42 days. At the end of each fasting period performance, fillet and whole-body proximal composition, and whole-body fatty acid profile were compared among fish before and after fasting. Additionally, fillet fatty acid daily loss was compared in fasted fish from different treatments. The results showed that body weight was not significantly impacted by fasting. However, at 17 °C fasting at all three stages had a negative impact on fillet weight and total fatty acid daily loss. With few exceptions, saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids from n-6 series (n-6 PUFA) were preserved in fillet of fish at 17 °C, while higher daily losses of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and consequently polyunsaturated from n-3 series (n-3 PUFA) were observed in these same fish and in smaller fish at 13 °C. The results presented in this study provide important information regarding the influence of fasting and temperature on chinook salmon performance and metabolism, providing basis for future nutritional and compositional studies for this important commercial species.

Effect of dietary black soldier fly larvae meal on fatty acid composition of lipids and sn-2 position of triglycerides of marketable size gilthead sea bream fillets

Insects are an alternative protein source recently adopted in aquacultured carnivorous species. However, the replacement of marine ingredients with insect meal might cut down the n−3 polyunsaturated fatty acid (PUFA) of fish fillet, a fraction of great interest for human nutrition. Recently, it has been shown that different animal species and the human species better absorb the dietary fatty acids esterified in the sn-2 position of the triglyceride (TG) than those contained in the sn-1 and sn-3 positions. Hence, the present paper aimed to evaluate in which extent replacing fishmeal with insect meal could alter not only the fillet fatty acid (FA) profile, but even the FA distribution inside the TGs. Specifically, three-hundred and sixty gilthead sea bream (Sparus aurata L.) were randomly divided into four groups with three replicates each. The fish were fed for 120 days four isoenergetic, isolipidic and isoproteic diets where fishmeal was substituted by Hermetia illucens (HI) larvae meal. The inclusion levels were 0% (HI0), 9.2% (HI9), 18.4% (HI18) and 27.6% (HI27), corresponding to 0, 25, 50 and 75% of fishmeal substitution, respectively. At the end of the trial, 10 fish per group were analyzed for marketable traits, fillet color values and lipid composition. Dietary intervention did not affect any of the considered marketable traits and the fillet color. Major changes were observed in the FA profile of the fillet lipids. The fillets from fish fed HI18 and HI27 contained the highest amount of saturated fatty acids while their n-3 PUFA were significantly reduced in comparison with HI0 and HI9. Analogous variations were observed in the FA composition of the TG fraction. On the contrary, dietary HI did not reduce the overall n-3 PUFA positioned in the sn-2 of TG, nor eicosapentaenoic acid (EPA) percentage. In conclusion, dietary HI inclusion did not substantially modify the presence of important fatty acids for human nutrition (i.e., EPA and DHA) in the sn-2 position of the fillet triglycerides, increasing the chances to be better assimilated and absorbed by humans.

Effects of dietary supplementation with filamentous microalgae (Oedocladium sp. or Tribonema ultriculosum) on growth performance, fillet fatty acid composition, skin pigmentation, and immune response of yellow catfish Pelteobagrus fulvidraco

AbstractA 40‐day feeding trial was conducted to investigate the effect of dietary microalgae Oedocladium sp. or Tribonema ultriculosum supplementation on growth performance, fillet fatty acid composition, skin pigmentation, and immune response of yellow catfish Pelteobagrus fulvidraco. Two hundred and seventy experimental fish (51.19 ± 1.17 g) were distributed among nine net cages (2 × 2 × 2 m3) in a randomized design and were fed diets containing 0% (control), 4% Oedocladium meal (Oedocladium), and 5% T. utriculosum meal (Tribonema) to apparent satiation twice a day. After the feeding trial, a hypoxic stress test was conducted to evaluate the effect of dietary microalgal supplementation on fish immune response. Compared to the control, microalgal supplementation did not affect fish growth performance. Dietary supplementation of T. utriculosum significantly increased fillet contents of palmitoleic acid by 100.44% and eicosapentaenoic acid by 12.51%, while the supplementation of Oedocladium meal in diet significantly increased the fish skin ventral lutein content by 61.6%. In addition, dietary Oedocladium or T. utriculosum supplementation significantly increased the plasma total superoxide dismutase activity (before hypoxic stress) and complement component 3 contents (after hypoxic stress). The addition of T. utriculosum meal also significantly increased the plasma immunoglobulin M content regardless of hypoxic stress. These results demonstrated Oedocladium sp. and T. utriculosum can be used to enhance fillet nutritional quality, skin pigmentation, and fish immune response.

Growth, Chemical Composition, Histology and Antioxidant Genes of Atlantic Salmon (Salmo salar) Fed Whole or Pre-Processed Nannochloropsis oceanica and Tetraselmis sp.

New sustainable feed ingredients are a necessity for the salmon aquaculture industry. In this study, we examined the effect of pre-extrusion processing of two microalgae, Nannochloropsis oceanica and Tetraselmis sp., on the growth, fatty acid content in the flesh and health of Atlantic salmon. The fish were fed one of the following five diets for nine weeks: (1) CO: a fish meal-based control (basal) diet, (2) NU: a Nannochloropsis diet, (3) NE: a pre-extruded Nannochloropsis diet, (4) TU: a Tetraselmis diet, and (5) TE: a pre-extruded Tetraselmis diet. The algae-incorporated diets contained 30% of the respective microalgae. Our results showed that the best growth performance was achieved by the CO diet, followed by the NE diets. Feeding of unprocessed Nannochloropsis and Tetraselmis resulted in a significant reduction in enterocyte vacuolization compared to the CO feeding. A significant effect of processing was noted in the fillet fatty acid content, the intestine and liver structure and the expression of selected genes in the liver. The expression of antioxidant genes in both the liver and intestine, and the accumulation of different fatty acids in the fillet and liver of the extruded algae-fed groups, warrants further investigation. In conclusion, based on the short-term study, 30% inclusion of the microalgae Nannochloropsis oceanica and Tetraselmis sp. can be considered in Atlantic salmon feeds.