HUFA Levels Research Articles

The effects of diet, salinity and temperature on HUFA accumulation in Artemia

Artemia nauplii is an important live food item for marine fish and crustaceans. However, the HUFA content of Artemia from different origins varies greatly and is generally low. Compared with other species or strains, Artemia cysts in Tibet salt lakes have very high HUFA content, which may be related to their unique living conditions. This study determined the effects of dietary HUFA (P. tricornutum and C. zofingiensis), salinity (4%, 8%, and 12%), and temperature (14 °C, 19 °C, and 24 °C) on the HUFA accumulation of Lagkor Co Artemia tibetiana after 14-day culture, in comparison with Great Salt Lake Artemia franciscana. The results showed that the HUFA profile of Artemia was closely related to the dietary HUFA level, and the low temperature and low salinity could significantly increase the ARA, EPA, and DHA content. PCA results showed that the fatty acid distribution patterns of the two Artemia species were mostly affected by dietary fatty acids, which were greater than those of temperature, salinity, and Artemia species. RNA-seq analysis and qRT-PCR verification revealed that low temperature and low salinity could promote the gene expression of fatty acid binding protein gene, long chain fatty acid elongase, and desaturase, suggesting these genes may be involved in the process of HUFA accumulation in A. franciscana. In conclusion, diet is a key factor affecting HUFA accumulation in Artemia, while low temperature and low salinity led to higher HUFA retention. The findings of this study provide a reference for revealing the mechanism of HUFA synthesis and metabolism of Artemia, and to develop the Artemia products with high HUFA content through manipulation of culture conditions.

Evaluation of dietary genistein on the antioxidant capacity, non-specific immune status, and fatty acid composition of common carp (Cyprinus carpio .L)

This experiment was performed to determine the effect of dietary genistein on the growth, antioxidation, immunity, as well as lipid metabolism of common carp (Cyprinus carpio.L). Six experimental feeds containing 0 (control group), 25, 50, 100, 500 or 1000 mg/kg of genistein were respectively formulated. The feeds were randomly assigned to triplicate tanks with 30 fish (initial weight (20.59 ± 0.69) g) for 8 weeks. All the growth parameters were significantly improved by supplementation with 100 and 500 mg/kg genistein. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were reduced, but the acid phosphatase (ACP) activity was increased in serum of the 100 mg/kg genistein group. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) levels were significantly increased in serum when the feed was supplemented with 500 mg/kg of genistein. The total cholesterol (TC), triglyceride (TG), and low–-density lipoprotein cholesterol (LDL-C) levels in serum were reduced in the genistein (100 and 500 mg/kg) supplement groups. The mRNA expression levels of the pro-inflammatory cytokines, such as interleukin 1 (il-1), the nuclear factor kb (nf-kb), and il-8 were reduced, but the expressions of anti-inflammatory cytokines, such as transforming growth factor-b (tgf-b) and il-10 were enhanced in the head kidney and spleen tissues after genistein supplementation. Furthermore, the immune enhancement of genistein was confirmed by increasing the survival rate of common carp to Aeromonas hydrophila challenge. In addition, the fatty acids profile in the liver and muscle of common carp indicated that an increase of muscle total PUFA, especially n-3 PUFA and HUFA levels in 100 or 500 mg/kg genistein supplement groups. Meanwhile, after the feeding trial, the amount of total PUFA in the liver was significantly elevated in the 500 mg/kg genistein group. As the acsl6 and elovl5 mRNA expressions in the liver were enhanced after genistein treatment, the biosynthesis ability of endogenous HUFA may be enhanced. Moreover, lipogenesis-related genes in the liver were down-regulated after genistein treatment. Therefore, 100 and 500 mg/kg of genistein can significantly improve growth, body composition and lipid metabolism, enhance the antioxidant and immunity of common carp.

Regulation of growth, fatty acid profiles, hematological characteristics and hepatopancreatic histology by different dietary n-3 highly unsaturated fatty acids levels in the first stages of juvenile Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding experiment was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFAs) on growth performance, fatty acid profiles, hematological characteristics and hepatopancreatic histology in juvenile Pacific white shrimp (Litopenaeus vannamei) (initial average weight, 0.14 ± 0.01 g). Six isoproteic and isolipidic diets were formulated with graded levels of n-3 HUFA (0.24, 0.53, 0.86, 1.25, 1.58 and 1.97 % of dry matter), and the 0.24 % group was used as control group. The results revealed that shrimp fed the diet containing 0.86 % n-3 HUFA had highest weight gain (WG) and specific growth rate (SGR), and the feed conversion ratio (FCR) showed the minimum at the same level. Shrimp muscle fatty acid profiles reflected that of diet. The contents of triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) in serum decreased along with n-3 HUFA levels increasing. The activity of superoxide dismutase (SOD) in hepatopancreas was highest significantly at the level of 0.86 % n-3 HUFA group than that in other groups. The content of malondialdehyde (MDA) in hepatopancreas increased with the increasing of n-3 HUFA levels, which reached the maximum value in 1.97 % group and was significantly higher than that in control group. The levels of n-3 HUFA could obviously affect on the cell morphology and lipid deposition in hepatopancreas of L. vannamei. Results of this study suggested that shrimp fed moderate dietary n-3 HUFA could enhance growth, feed utilization, antioxidant capacity and reduces excess lipid deposition.

Utilization of grape seed oil as a dietary lipid source in rainbow trout (Oncorhynchus mykiss) diets

ABSTRACT A 60-day feeding trial was conducted to determine the effects of different levels of grape seed oil (GO) on growth performance, digestive enzyme activity, fillet proximate and fatty acid composition of rainbow trout (Oncorhynchus mykiss) juveniles (40.17 ± 0.04 g). Five experimental diets were formulated where fish oil (FO) was replaced with 0 (D1), 25 (D2), 50 (D3), 75 (D4) and 100 (D5) % GO. The growth performance was significantly improved with increasing GO levels up to 50% after which fish growth declined (P < .05). Fillet fatty acid composition was showed significantly highest n-6 PUFA levels with increasing GO in diets, while n-3 HUFA levels especially EPA and DHA were significantly decreased (P < .05). Fish fed on diets containing higher levels of GO revealed a decrease in α-amylase activity, whereas trypsin, total alkaline protease, and lipase activities increased significantly with increasing GO levels up to 50% and then decreased. Based on the findings of the present study, it could be concluded that GO could be included in diets up to 50% where it had the best performance over the other diets tested in the present experiment.

Effects of dietary n-3 highly unsaturated fatty acids on growth, non-specific immunity, expression of some immune-related genes and resistance to Vibrio harveyi in hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu)

This study was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) on growth performance, non-specific immunity, expression of some immune-related genes and resistance to Vibrio harveyi in juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatu). Six isoproteic and isolipidic experimental diets were formulated with graded levels of n-3 HUFA (0.65, 1.00, 1.35, 1.70, 2.05 and 2.40% of dry matter, respectively), and the 0.65% group was used as control group. Each diet was randomly allocated to triplicate groups of fish in 1000 L fiberglass tank, and each tank was stocked with 40 fish (initial weight 12.06 ± 0.01 g) for 8 weeks. Results showed that feed conversion ratio (FCR), survival rate (SR), hepatosomatic index (HSI) and condition factor (CF) were all not significantly affected by dietary n-3 HUFA levels (P > 0.05). Weight gain (WG) and specific growth rate (SGR) in 1.35% group were significantly higher than those in 2.40% group (P < 0.05). Crude lipid of body in 1.00% group was significantly lower than that in 1.70% and 2.40% groups (P < 0.05). Liver and muscle fatty acid profiles reflected that of diets. Before challenge with Vibrio harveyi, the activity of serum superoxide dismutase (SOD), catalase (CAT) and content of complement 3 (C3) in 1.35% and 1.70% groups significantly higher than those of control group (P < 0.05). After challenge with Vibrio harveyi, serum CAT, glutathione peroxidase (GSH-PX), lysozyme (LZM) and C3 all increased sharply, while SOD showed the opposite trend. Before challenge with Vibrio harveyi, the expression levels of intestine toll-like receptor 22 (TLR22) and myeloid differentiation factor 88 (MyD88) mRNA in 2.40% group were significantly increased, and the expression levels of tumour necrosis factor α (TNF-α) and interleukin 1β (IL-1β) mRNA in 2.05% group were significantly higher than those in 1.00% and 1.35% groups (P < 0.05). In addition, the TLR22 and IL-1β mRNA levels in kidney of 1.70% group were significantly lower than those in control group (P < 0.05). After challenge with Vibrio harveyi, the expression level of MyD88 mRNA in intestine of 1.35% group was significantly higher than that in 1.00% group and from 1.70% to 2.40% groups (P < 0.05), while TNF-α and IL-1β obtained minimum values in 1.70% group. In the kidney, the interleukin 10 (IL10) mRNA expression was significantly higher in 1.70% group than that in other groups, while the IL-1β expression in 1.70% group was on the contrary and significantly lower than that in 2.40% group (P < 0.05). Results of this study suggested that moderate dietary n-3 HUFA (1.47%–1.70% HUFA) could improve the growth performance, non-specific immunity and inhibit the inflammatory response of hybrid grouper.

Interactions of season, sex and size on nutrient composition of freshwater crayfish (Astacus leptodactylus Eschscholtz, 1823) from Lake Eğirdir

Effects of interaction of season, sex and size on nutrient composition and fatty acid profiles of freshwater crayfish (Astacus leptodactylus) caught from the Eğirdir Lake were investigated on a factorial level. In the factorial analysis; 4 levels of season factors (autumn, winter, spring, summer), 2 levels of sex factor (male, female) and 1 level size factor were available. According to the results of biochemical analysis, effects of seasons were determined on crude protein and moisture levels. Crude ash levels changed depending on sex and season. There were no interactions of these three factors on the crude fat levels. The season and sex affected on LA, α-LNA and ∑HUFA levels. ARA, EPA, DHA, ∑SFA and ∑PUFA levels were affected from seasonal changes. Interaction of season/sex affected to ∑MUFA levels. The crude protein content, DHA, EPA and n-3 contents in tail muscle of A. leptodactylus increased by feeding in summer while these contents decreased by gonadal development in autumn. Therefore, in terms of nutritional protein contents, EPA, DHA and n-3 of this species were higher in summer. EPA, n-3 and DHA contents are important for A. leptodactylus.

Effect of increasing n-3 HUFA content in enriched Artemia on growth, survival and skeleton anomalies occurrence of greater amberjack Seriola dumerili larvae

Elevated mortality during early stages and high occurrence of skeletal anomalies are major concerns in Greater amberjack (Seriola dumerili) juvenile's production. Identification of nutritional requirements during live prey feeding stages, particularly those related with n-3 HUFA would help to formulate specific diets for this species improving larval survival and reducing skeleton anomalies. In this study S. dumerili larvae were reared from 17 to 35 days post hatching (dph). Larvae were fed Artemia sp. containing five different n-3 HUFA levels from 2.7 to 20.5% TFA. Growth, survival, skeletal anomalies occurrence and larval biochemical composition were determined. Best growth, final survival and survival after air stress test were achieved in the range of dietary n-3 HUFA concentrations, between 5 and 20%TFA. The lowest occurrence of skeletal anomalies was achieved in fish fed 12% n-3 HUFA content in Artemia, and the occurrence of cranial anomalies was correlated to increased dietary n-3 HUFA levels. Besides, whole body larval fatty acid profiles showed a positive correlation with dietary n-3 HUFA. Based on the overall results the recommended n-3 HUFA dietary level during Artemia feeding for larval S. dumerili was suggested between 12 and 17%TFA.

Regulation of growth, antioxidant capacity, fatty acid profiles, hematological characteristics and expression of lipid related genes by different dietary n-3 highly unsaturated fatty acids in juvenile black seabream (Acanthopagrus schlegelii)

An 8-week feeding trial was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acid (n-3HUFA) on growth performance, antioxidant capacity, fatty acid profiles, hematological characteristics and expression of some lipid related genes of juvenile black seabream (Acanthopagrus schlegelii) (initial weight 3.77±0.00g). Five isonitrogenous and isolipidic experimental diets were formulated with graded levels of n-3 HUFA (0.23, 0.87, 1.29, 1.75 and 2.53% of dry weight, DHA/EPA ratio approximately at 1.0). The results revealed that fish fed the diet containing 1.75% n-3 HUFA had higher weight gain (WG) and specific growth rate (SGR) than those fed the control diet. Fish fed diets containing 1.29% and 1.75% n-3 HUFA had higher feed efficiency (FE) than those fed the other diets. Hepatic and muscular fatty acid profiles reflected that of diets. The content of malondialdehyde (MDA) increased both in the serum and liver of fish fed high n-3 HUFA level diets, and the highest hepatic activity of glutathione peroxidase (GSH-PX) was recorded in fish fed the diet containing 1.29% n-3 HUFA. The expression of accα, g6pd, fas, srebp-1, lpl, atgl, hsl, elovl5 and fads2 was down-regulated in fish fed the diets with high n-3 HUFA levels. However, the expression levels of 6pgd and pparα significantly increased when the dietary contents of n-3 HUFA increased from 0.23% to 1.29% and then decreased when dietary n-3 HUFA levels increased from 1.75% to 2.53%. The highest expression of cpt1a was found in fish fed the diet containing 1.75% n-3 HUFA. The content of cholesterol (CHOL) in serum increased along with n-3 HUFA level. Over all, this study indicated that fish fed moderate dietary n-3 HUFA (1.34–1.80% n-3 HUFA) could enhance growth, feed utilization and antioxidant capacity. Different dietary levels of n-3 HUFA could strongly affect expression levels of some lipid metabolism relevant genes of the juvenile black seabream. This may contribute to our understanding of the mechanisms related to lipid metabolism (anabolism and catabolism) effects of different dietary levels of n-3 HUFA.

Combination effects of dietary EPA and DHA plus alpha-tocopherol: effects on performance and physiological status of Caspian brown trout (Salmo trutta caspius) fry

The effects of dietary n-3 highly unsaturated fatty acids [eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)] with α-tocopherol on growth, non-specific immune response and oxidative status were investigated in Caspian brown trout, Salmo trutta caspius, fry. Six experimental diets containing three different dietary levels of n-3 HUFAs (low: 1 + 0.5% of total fatty acids, DHA+ EPA, medium: 2 + 1%, DHA + EPA, high: 4 + 2%, DHA + EPA) with two different levels of α-tocopherol (low: 300 and high: 1000 mg kg−1 diet) were prepared and named: LL, LH, ML, MH, HL and HH (HUFA/α-tocopherol) groups, respectively. Diets were fed to triplicate groups of 60 fry with an initial weight of 600 ± 25 mg for 10 weeks. Results showed that increase in dietary DHA and EPA up to high level improved fry growth in terms of the body weight and specific growth rate, particularly when dietary α-tocopherol levels were high, suggesting a higher antioxidant protection value when these fatty acids are high. At all dietary n-3 HUFA levels, increase in α-tocopherol from low to high level enhanced the alternative complement (ACH50) activity. Fry fed diets medium and high n-3 HUFA displaying significantly higher lysozyme activity (P < 0.05). Moreover, fish fed medium or high levels of n-3 HUFA had significantly lower prostaglandin E2 (PGE2) than those fed low n-3 HUFA (P < 0.05). Significant differences in antioxidant enzymes (catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase and superoxide dismutase) activity were also observed between groups, with higher activity in high levels of n-3 HUFA (P < 0.05). Results of this study suggest that the effect of dietary n-3 HUFA on examined non-specific immunity parameters are not uniform; however, these impacts are closely related to the α-tocopherol supplement and their interaction. In conclusion, increased dietary levels of n-3 HUFA and α-tocopherol would enhance growth performance and welfare of this species.

Effects of phospholipid addition to diets with different inclusion levels of fish oil on growth and fatty acid body composition of juvenile swimming crabPortunus trituberculatus

Six experimental diets were designed with two phospholipid (PL; 0% and 1.5%) and three fish oil levels (0%, 1% and 3%) to evaluate the effects of dietary fish oil and PL levels on growth, survival and fatty acid composition of juvenile swimming crab, Portunus trituberculatus. Diets were iso-energetic and iso-nitrogenous and each diet was fed to triplicate groups (initially weight, 24.88 ± 0.04 g per crab) for 59 days. Weight gain (WG) and specific growth rate (SGR) increased with dietary PL addition to 0% fish oil-supplemented diets (P < 0.05). On the other hand, WG and SGR decreased with dietary PL addition to 3% fish oil diets (P < 0.05). Crabs fed PL supplemented diets had higher haemolymph low-density lipoprotein cholesterol concentrations and muscle crude lipid levels (P < 0.05) than crabs fed a none PL supplemented diet. The percentage of highly unsaturated fatty acids (HUFA; % total FA) in both polar and neutral lipids fractions of muscle tissue only increased in case of PL addition to 0% and 1% fish oil-supplemented diets (P < 0.05). HUFA levels in the neutral lipids fraction of the hepatopancreas increased by dietary PL addition at each dietary fish oil level (P < 0.05). In this study, both dietary fish oil and PL addition contributed to a high n-3/n-6 ratio in muscle and hepatopancreas of P. trituberculatus. In conclusion, PL addition is only meaningful with fish oil-deficient diets, in which case it enhanced lipid transport and HUFA absorption efficiency, hence improving the nutritional value of the diet.

Biomarkers of bone development and oxidative stress in gilthead sea bream larvae fed microdiets with several levels of polar lipids and α-tocopherol

Although dietary marine phospholipids are able to improve culture performance of marine fish larvae in a further extend than soybean lecithin, both types of phospholipids (PL) markedly increase oxidative risk. The inclusion of a fat-soluble antioxidant such as the vitamin E α-tocopherol could allow a better control of oxidative stress. The objective of this study was to determine the combined effect of graded levels of α-tocopherol with different levels and sources of krill phospholipids (KPL) and soybean lecithin (SBL) on growth, survival, resistance to stress, oxidative status, bone metabolism-related genes expression and biochemical composition of sea bream larvae. Sea bream larvae were completely weaned at 16 dph and fed for 30 days seven microdiets with three different levels of PL (0, 40 and 80 g kg−1 diet) and two of α-tocopherol 1500 and 3000 mg kg−1 diet. Sea bream larvae fed diets without PL supplementation showed the lowest survival, growth and stress resistance, whereas increase in PL, particularly KPL, markedly promoted larval survival and growth. However, feeding SBL markedly increased TBARs and GPX gene expression increasing the peroxidation risk in the larvae. Besides, KPL inclusion improved incorporation of n-3 HUFA and, particularly, EPA into larval tissues, these fatty acids being positively correlated with the expression of BMP-4, RUNX 2, ALP, OC and OP genes and to bone mineralization for a given larval size class. The increase in dietary α-tocopherol tends to improve growth in relation to the n-3 HUFA levels in the diet, denoting the protective role of this vitamin against oxidation. Indeed, dietary α-tocopherol decreased the oxidative stress in the larvae as denoted by the reduction in larval TBARs contents and gene expression of SOD and CAT, but not GPX. Thus, increase in dietary α-tocopherol effectively prevented the formation of free radicals from HUFA, particularly EPA, but did not affect the incidence of bone anomalies or the expression of genes related to osteogenetic processes.

Ontogenetic changes in lipids, fatty acid, and body composition during larval stages of Caspian Kutum (Rutilus frisii kutum)

Body composition and fatty acid profile of the body tissue of Caspian kutum (Rutilus frisii kutum) fish larvae were determined from fertilized egg to 50 days post hatching (dph). Feeding with rotifer started from day 3 to day 7 thereafter they were fed with dry food until the end of the experiment. The changes observed in lipid content and the decrease in lipid levels during larval ontogeny reflect the utilization and mobilization of lipids during both embryogenesis and larvae development. During this study, palmitic and stearic acids were the most abundant saturated fatty acid (SAFA).In kutum larvae, no utilization of palmitic and stearic acids was observed until 20 dph. It thereafter was utilized as an energy source. Oleic and palmitoleic cacids were the predominant monounsaturated fatty acid (MUFA). Oleic and palmitoleic acids utilized until 10 and 25 dph, respectively thereafter they increased. DHA, EPA and ARA were the major polyunsaturated fatty acids (PUFA). The decrease in levels of DHA and EPA denotes their utilization as an energy substrate by kutum larvae. ARA decreased during larval ontogeny, reflecting dietary values. With regard to reared kutum larvae in fresh water and the low levels of HUFA in larval diet, it can be said that kutum larvae possibly are quite capable of elongating and desaturating C18 to C20 PUFA. In case of proximate analysis, the percentage of body protein and ash increased trend during ontogeny while the percentage of body lipid and moisture decreased trend during larval growth.

Replacement of Reduced Highly Unsaturated Fatty Acids (HUFA Deficiency) in Dilative Heart Failure: Dosage of EPA/DHA and Variability of Adverse Peroxides and Aldehydes in Dietary Supplement Fish Oils

Objectives: To explore the rationale for ω-3 fatty acids in heart failure treatment, the dosage of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) for replacing low levels of highly unsaturated fatty acids (HUFA deficiency) was examined. To judge the usefulness of various EPA/DHA preparations, their content of peroxides and aldehydes was determined. Methods: In 298 patients with dilative heart failure, the serum HUFA level was assessed by gas chromatography. In ω-3-acid ethyl esters 90 (Omacor/Lovaza, approved by the Food and Drug Administration and the European Medicines Agency) and 63 dietary supplement fish oils, oxidation products were determined by photometry. Results: Increasing serum HUFA from the lower (4.3 ± 1.0%) to the upper (9.5 ± 1.5%) tertile would be associated with an increased left ventricular (LV) ejection fraction (34.1 ± 9.9 vs. 28.3 ± 9.5%, p < 0.01) and reduced LV enddiastolic diameter (63.5 ± 7.1 vs. 66.9 ± 7.4 mm) requiring at least 2 g EPA/DHA daily. In fish oils, the peroxide and alkenal level varied greatly, i.e. peroxide value ≤5 mEq/kg in only 7 and ≤10 mEq/kg in 38 fish oils. Compared with equivalent doses of ω-3-acid ethyl esters 90, the mean peroxide intake would be 8.6 ± 6.1 and the alkenal intake 10.9 ± 4.4 times higher in fish oils. Conclusions: Levels of adverse oxidation products should be considered when targeting HUFA deficiency or treating patients with myocardial infarction or high triglycerides.

Effect of Dietary n‐3 highly unsaturated fatty acids on Growth, Body Composition and Fatty Acid Profiles of Juvenile Black Seabream, Acanthopagrus schlegeli (Bleeker)

AbstractAn 8‐wk feeding trial was conducted to investigate the effects of dietary n‐3 highly unsaturated fatty acids (n‐3 HUFA) on growth, body composition, and fatty acid profiles of juvenile Acanthopagrus schlegeli. Three replicate groups of fish (initial mean weight: 8.08 ± 0.09 g, mean ± SD) were fed diets with different levels of n‐3 HUFA (0.76%, HUFA0.76; 0.83%, HUFA0.83; 0.90%, HUFA0.90; 0.97%, HUFA0.97; 1.04%, HUFA1.04; 1.12%, HUFA1.12) at 12.9% of total lipid, with a constant eicosapentaenoic acid (EPA, 20:5n‐3) to docosahexaenoic acid (DHA, 22:6n‐3) ratio of about 2.1. Hepatosomatic index (HSI) and intraperitoneal fat (IPF) ratio were all linearly depressed by dietary n‐3 HUFA levels (P &lt; 0.05), and condition factor (CF) was not affected. Adipocyte diameter in IPF decreased with the elevation of dietary n‐3 HUFA and significance occurred between group HUFA0.90 and HUFA1.12. Lipid content in dorsal muscle was significantly lowered by dietary n‐3 HUFA compared to fish fed diet HUFA0.76. No significance was found in whole fish proximate composition. In liver, dorsal muscle and IPF, ∑SFA, 16:0 or ∑n‐3 HUFA were all positively correlated with dietary n‐3 HUFA, while DHA to EPA ratios remained constant in 2.68, 2.86, and 3.60, respectively. Fatty acid synthase (FAS, EC 2.3.1.85) activities of all treatments remained constant at first and then were significantly elevated by dietary n‐3 HUFA higher than 0.97% (P &lt; 0.05). In contrast, hormone sensitive lipase (HSL, EC 3.1.1.3) changed following an opposite tendency. Quadratic analysis based on weight gain rate (WGR) indicated that dietary n‐3 HUFA requirement for juvenile black seabream was 0.94% of the diet in 12.9% lipid diets.

Effect of short-term fresh food supplementation on reproductive performance, biochemical composition, and fatty acid profile of Litopenaeus vannamei (Boone) reared under biofloc conditions

A 40-day trial was performed to evaluate the effect of short-term natural fresh food (FF) supplementation 20 days prior to ablation in Litopenaeus vannamei broodstock raised under biofloc conditions. Changes in biochemical composition and fatty acids profile were used as indicators of nutritional condition. Females that received FF supplementation (FLOC + FF) achieved better eggs production, spawned more promptly, and presented higher levels of HUFA in eggs as compared to those that did not received FF (FLOC). Proximate analysis of biofloc and microorganisms assessment showed a higher crude protein and lipid content in the FLOC + FF treatment (26.3 and 0.7 %) compared to FLOC treatment (18.4 and 0.3 %) and also demonstrated a higher concentration of filamentous cyanobacteria and nematodes. The better outcomes obtained in females that received short-term FF supplementation justified the FF use in L. vannamei broodstock.

Effects of dietary n-3 highly unsaturated fatty acids on growth, nonspecific immunity, expression of some immune related genes and disease resistance of large yellow croaker ( Larmichthys crocea) following natural infestation of parasites ( Cryptocaryon irritans)

The study was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acid (n-3 HUFA) on growth, nonspecific immunity, expression of some immune related genes and disease resistance of juvenile large yellow croaker ( Larmichthys crocea) following natural infestation of parasites ( Cryptocaryon irritans). Six isoproteic and isolipidic diets were formulated with graded levels of n-3 HUFA ranging from 0.15% to 2.25% of the dry weight and the DHA/EPA was approximately fixed at 2.0. Each diet was randomly allocated to triplicate groups of fish in floating sea cages (1.0 × 1.0 × 1.5 m), and each cage was stocked with 60 fish (initial average weight 9.79 ± 0.6 g). Fish were fed twice daily (05:00 and 17:00) to apparent satiation for 58 days. Results showed that moderate n-3 HUFA level (0.98%) significantly enhanced growth compared with the control group (0.15% HUFA) ( P < 0.05), while higher n-3 HUFA levels (1.37%, 1.79% and 2.25%) had detrimental effects on the growth though no significance was found ( P > 0.05). Nitro blue tetrazolium (NBT) positive leucocytes percentage of head kidney and serum superoxide dismutase (SOD) activity increased with increasing n-3 HUFA from 0.15% to 0.60%, and decreased with further increase of n-3 HUFA from 0.60% to 2.25% ( P < 0.05). Serum lysozyme activity increased significantly as n-3 HUFA increased from 0.15% to 1.37%, and then decreased with n-3 HUFA from 1.37% to 2.25% ( P > 0.05). There were no significant differences in phagocytosis index (PI) of head kidney leucocytes among dietary treatments ( P > 0.05). The hepatic mRNA expression of Toll-like receptor 22 (TLR22) and Myeloid differentiation factor 88 (MyD88) was significantly up-regulated in fish fed the diets with low or moderate levels, while in kidney this increment was only found at specific sampling time during the natural infestation of parasites. The 13 d cumulative mortality rate following natural infestation of parasites decreased with n-3 HUFA increased from 0.15% to 0.60% ( P < 0.05), and significantly increased with n-3 HUFA from 0.60% to 2.25% ( P < 0.05). Results of this study suggested that fish fed low or moderate dietary n-3 HUFA had higher growth, nonspecific immune responses, expression levels of some immune related genes and disease resistance of large yellow croaker following natural infestation of parasites and dietary n-3 HUFA may regulate fish immunity and disease resistance by altering the mRNA expression levels of TLR22 and MyD88.

Requirements for n-3 highly unsaturated fatty acids in feeding juvenile Iranian sturgeon (Acipenser persicus) and its effects on growth, carcass quality, and fatty acid composition

A 60-day feeding experiment was carried out on juvenile Iranian sturgeon (Acipenser persicus) to evaluate the effects of different percentages of canola oil and fish oil containing n-3 highly unsaturated fatty acids (n-3 HUFA) on fish growth and fatty acid composition. The requirement for n-3 HUFA of juvenile Iranian sturgeon (48.4 ± 1.98 g) was studied by feeding the fish with various diets containing six different percentage of n-3 HUFA ranging from 1.56 to 17.25 (% of total fatty acids). Neither the weight gain, feed conversion ratio, condition factor, specific growth rate nor the protein efficiency ratio showed any significant differences between the dietary treatments nor in the body composition of juvenile Iranian sturgeon (P > 0.05); also there were no significant difference with respect to the effect of the dietary treatment (P > 0.05) on the blood parameters, for the content of plasma protein, glucose, cholesterol, and triglyceride. The fatty acid composition of the carcass of the Iranian sturgeon fed with the diets containing various levels of n-3 HUFA was reflected by the dietary fatty acid composition. The content of n-3 HUFA in the fish increased with an increase in dietary n-3 HUFA levels. The results indicate that the dietary n-3 HUFA had no effect on the growth of juvenile Iranian sturgeon.

Effect of dietary n-3 HUFA on growth performance and tissue fatty acid composition of gibel carp Carassius auratus gibelio

A 12-week growth trial was conducted with gibel carp Carassius auratus gibelio (initial weight: 2.69 g) to evaluate the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) on growth performance and tissue fatty acid composition. Five diets of different n-3 HUFA levels from 0 to 17 g kg(-1) diet were supplemented at 80 g kg(-1) dietary lipid by including fish oil (FO) at 0, 25, 50, 75 and 100% of supplemental lipid. The remainder was coconut oil. The results showed that fish fed FO25 and FO50 obtained highest specific growth rate and lowest with FO0. Feed efficiency was highest at FO100 and lowest at FO0. Apparent digestibility coefficient of lipid increased with increasing dietary n-3 HUFA. The fish fed FO0 diet had the lowest thiobarbituric acid reactive substance in serum and muscle and highest moisture and lowest lipid content in viscera. Fatty acid compositions of muscle and liver were correlated with dietary fatty acids. Fish muscle concentration of 20:5n-3 increased with increasing dietary n-3 HUFA while the concentration of 22:6n-3 was distinctly reduced in FO0 group. It suggested that 4 g kg(-1) n-3 HUFA in diet could permit gibel carp normal growth performance and provide considerable n-3 HUFA in fish muscle. Excessive n-3 HUFA showed impact on growth performance of gibel carp.

Dietary effects of n-3 highly unsaturated fatty acid levels on egg and larval quality, and the fatty acid composition of the eggs of Chilean flounderParalichthys adspersusbroodstock

The effects of dietary n-3 highly unsaturated fatty acid (n-3 HUFA) on eggs and larval quality were investigated in the Chilean flounder Paralichthys adspersus. Broodstock were fed with three formulated diets with similar proximate compositions but different n-3 HUFA (2.1%, 3.1% or 4.1%) estimated levels from 5 months before and during the spawning period. The diet with an intermediate n-3 HUFA level resulted in a significantly higher (P<0.05) percentage of buoyant eggs (68.2 ± 2.9%), fertilization (92.8 ± 3.9%), normal cell cleavages (93.5 ± 1.9%), hatching rate (87.7 ± 4.1%) and normal larvae (76.3 ± 3.7%) compared with the other two diets. In contrast, high levels of n-3 HUFA produced larvae with a higher survival capacity when subjected to fasting. The diet with the lowest content of n-3 HUFA produces lower quality eggs and larvae. The n-3 HUFA level in eggs increased with an increase in the dietary level, and the n-3/n-6 ratios were 1:1, 2:1 and 3:1. The DHA/EPA and EPA/ARA ratios of 2 and 4 in eggs, respectively, were associated with improved egg and larval quality and were similar to the ratios found in eggs from wild broodstock. Attainment of optimal fatty acid contents in broodstock diets is one of the key factors for producing the high-quality spawning required for managed culture of this flounder.

Fatty acid profiles of microdiets for marine fish in Turkey

Lipid contents and fatty acid profiles in the commercial microdiets for farming marine fish species were determined. Twenty microdiet samples were taken from marine fish farms on the Aegean region of Turkey throughout 2006-2007. Of the 20 microdiet samples, 5 were produced in Turkey and 15 were imported. The fatty acid analysis of the microdiets was made by gas-liquid chromatography using helium as the carrier gas. The lipid levels of the microdiets produced in Turkey by different companies ranged from 9.5 ± 0.05% to 11.6 ± 0.14% (P < 0.05). In contrast, the lipid levels of imported microdiets were between 10.6 ± 0.20% and 17.2 ± 0.14% (P < 0.05). n-3 polyunsaturated fatty acids (n-3 PUFA) levels in the microdiets ranged from 7.1 ± 0.03% to 24.8 ± 0.03% of total fatty acids (P < 0.05). Similarly, n-3 highly unsaturated fatty acid (n-3 HUFA) levels in the microdiets ranged from 6.1 ± 0.01% to 22.8 ± 0.02% of total fatty acids (P < 0.05). n-3 highly unsaturated fatty acids (n-3 HUFA) levels in the microdiets were found between 0.6 ± 0.00% and 3.6 ± 0.01% of dry weight of diets (P < 0.05). Docosahexaenoic acid (DHA) levels of these microdiets were between 0.3 ± 0.00% and 2.0 ± 0.03% of the dry weight of diets (P < 0.05). Eicosapentaenoic acid (EPA) levels in the dry weight of diets were between 0.3 ± 0.01% and 2.2 ± 0.01% (P < 0.05). Arachidonic acid (ArA) levels in the microdiets were also found between 0.3 ± 0.01% and 0.9 ± 0.01% of total fatty acids (P < 0.05). The value of DHA/EPA ratios in the microdiets ranged from 0.5 ± 0.01 to 2.0 ± 0.01 (P > 0.05). The results showed that the total lipid or n-3 and n-6 HUFA percentages especially DHA, EPA, ArA levels, and DHA/EPA ratios in the microdiets covered essential fatty acid (EFA) needs for larvae or early juvenile sea bass and sea bream. However, microdiets 3 and 13 had a slightly lower ratio of n-3 HUFA levels required for larval or early juvenile of these species.