Lipid Content Of Fish Research Articles

PAHs in Water, Sediment and Biota in an Area with Port Activities.

The study reports concentration of 16 PAHs in sediment, water, plankton and in muscle and liver of sampled fishes from Paranagua Bay in Southern Brazil. According to the range of PAHs concentration found in sediments (ΣPAHs 15.33-133.61µgg-1) and water (ΣPAHs 51.20-162.37µgL-1), the area was characterized as slightly polluted. In contrast, significant concentration of PAHs was found in fish and plankton, ranging from 26.52 to 2055.00µgg-1 and 175.41 to 2096.10µgg-1, respectively. The concentrations were 15 times more than in sediments. Even though the concentration of PAHs in water and sediments are low, the concentration in fish tissues are alarmingly. The hypothesis of bioaccumulation is not discharged. Accumulation levels of PAHs in the biota were used to calculate biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For example, fish sampled from site 11 had a BAF of 49 and BSAF of 2.3, whereas for plankton the BAF was 16.3 and BSAF 0.7. Mean values of BAF and BSAF were higher in plankton samples. It is known that PAHs are enzymatically metabolized by organisms, thus the lower BSAF in fish might have resulted from biochemical transformation. Statistical analysis indicates no significant correlation between total PAHs concentration in fish tissues and total lipid content in fishes (p > 0.1).Accumulation in tissues is controlled by lipid content, although factors, such as spatial distribution of compounds, trophic level, and behavior of each species in the environment, must be considered. Besides, size and nutritional conditions can affect both absorption as well as metabolic process and excretion. A positive and significant correlation was found between total PAHs and trophic positions obtained from FishBase data (r2 = 0.784; p < 0.05). Thus, it seems that the area, with great influence of urban and industrial activities, and the bioaccumulation compounds, such as PAHs, depend on others factors, as well as resuspension of sediments and releasing of compounds for biota.

Taurine requirement for growth and nitrogen accretion of European sea bass (Dicentrarchus labrax, L.) juveniles

A growth trial was conducted to determine the dietary taurine requirement for European sea bass juveniles fed plant feedstuffs-based diets. Eight isoproteic (45% crude protein) and isolipidic (18% crude lipid) diets were formulated containing a mixture of plant feedstuffs and fish meal (corresponding to 80% and 20% of total dietary protein, respectively) and taurine (Tau) levels ranging from 0.2 to 1.7% (diets 0.2Tau; 0.3Tau; 0.4Tau; 0.5Tau; 0.7Tau; 0.9Tau; 1.2Tau; 1.7Tau). Triplicate groups of 12 fish (IBW = 55 g) were fed each diet for 10 weeks. Dietary Tau level up to 0.7% improved growth performance while maximum feed efficiency and protein efficiency ratios were obtained with a dietary Tau level of 1.2%. Whole-body lipid content of fish fed the 1.2 and 1.7% Tau diets was lower than in the other groups, while whole-body protein and ash contents, and hepatosomatic and visceral indexes were not affected by diet composition. Daily growth index, nitrogen retention, and feed efficiency were fitted to Tau levels using different models. The five-saturation kinetics model was selected as the more parsimonious model, and based on this model the dietary Tau requirement for European sea bass juveniles under the present experimental conditions was estimated to be 0.47–0.50% DM.

Efficiency of Dietary β-glucan Supplementation on Growth, Body Composition, Feed, and Nutrient Utilization in Juveniles of Pompano Fish (Trachinotus ovatus, Linnaeus, 1758)

An 8-week experiment was conducted to examine the effect of increasing levels of dietary β-glucan on the growth performance, feed utilization, and body composition of juvenile pompano (Trachinotus ovatus). Pompano (mean initial weight, 6.45 g) were fed five diets containing five levels of β-glucan (D1 (control): 0%; D2: 0.05%; D3: 0.10%; D4: 0.20%; and D5: 0.40%. Results showed that growth performance, body composition, efficacy of feed and nutrient utilization were significantly affected by dietary β-glucan levels. After 8-weeks of feeding, weight gain, daily weight gain, specific growth rate, final body weight, coefficient of variation were highest in pompano fed 0.05% and 0.10% β-glucan in the diet (P ≤ 0.034), while growth of fish fed 0.2% and 0.4% β-glucan did not significantly differ compared to fish fed the control diet (P ≥ 0.170). Survival rate of juvenile pompano was not influenced by β-glucan supplement in the diet (P ≥ 0.383). In addition, feed utilization daily feed intake, feed conversion ratio, and feed conversion efficiency were significantly lower in fish fed diets supplemented with 0.01–0.10% β-glucan (P ≤ 0.027). In contrast, feeds supplemented with 0.2 to 0.4% β-glucan did not influence the feed utilization of pompano after 56 days of diet feeding (P ≥ 0.051). Protein was significantly higher in the flesh of pompano fed 0.05% to 0.10% β-glucan (P ≤ 0.001), while lipid content in fish decreased significantly with graded levels of β-glucan in the diet (P ≤ 0.044). After 56 days, protein efficiency ratio (PER), protein productive value (PPV), and fractional rates of protein growth (Kg), were significantly higher in fish fed diets supplemented with 0.05 -0.10% β-glucan (P ≤ 0.025).

Growth, Survival, and Whole‐body Proximate and Fatty Acid Composition of Haddock, Melanogrammus aeglefinus L., Postlarvae Fed a Practical Microparticulate Weaning Diet

AbstractFurther development of high‐quality feeds for hatchery‐reared haddock in the North Atlantic would benefit from a standard formulation that can be used as a reference for hatcheries and laboratory studies. A practical microparticulate diet (PMD) developed and evaluated with newly metamorphosed juvenile haddock, Melanogrammus aeglefinus L., postlarvae is proposed. Survival of fish fed PMD was just as high (88–89%; P &gt; 0.05) as those fed a high‐quality imported feed (Biokyowa). Alternatively, fish fed PMD had higher (P &lt; 0.05) final fork lengths (39.5 vs. 35.1 mm), wet weights (851.3 vs. 580.2 mg) and weight gains (1637.2 vs. 1115.7%). No differences (P &gt; 0.05) in whole‐body moisture (846–857 g/kg), ash (17–18 g/kg), or protein (101 g/kg) contents were found. Lipid content of fish fed PMD (26 g/kg) was higher (P &lt; 0.05) than those fed Biokyowa (21 g/kg) despite PMD containing 15 g/kg lower dietary lipid, suggesting higher intake and/or lipid retention. The PMD formulation proved to be a highly suitable weaning diet for haddock postlarvae based on high feed acceptance, survival, and fish growth. Given the economic and logistical difficulties associated with importing commercial weaning feeds, this easily produced practical weaning diet has good potential for use by laboratory researchers and farm managers for hatchery‐based nutrition research with haddock postlarvae.

Effect of dietary fatty acid composition on growth, fatty acids composition and hepatic lipid metabolism in juvenile turbot (Scophthalmus maximus L.) fed diets with required n3 LC-PUFAs

A 12-week feeding experiment was conducted to investigate the effects of dietary fatty acids composition on growth performance, lipid deposition and some genes expression of hepatic lipid metabolism in juvenile turbot (Scophthalmus maximus L.) (mean initial body weight, 9.49±0.03g) fed diets with required n3 LC-PUFA. Juvenile turbot were fed diets with palm oil (PO), rapeseed oil (RO), soybean oil (SO) or linseed oil (LO) replacing the same levels of fish oil (FO), respectively. Each diet was randomly fed to triplicate tanks, and each tank was stocked with 35 fish. The results showed that growth performance and feed utilization of turbot fed diets with required n3 LC-PUFA were independent of dietary fatty acids composition. As expected, C16:0, C18:1n, C18:2n-6, C18:3n-3 and n3 LC-PUFAs level in liver were up to the maximum in the PO, RO, SO, LO and FO group, respectively, and significantly higher than that in the other groups (P<0.05). Fish fed the diet with RO had the lowest plasma triglyceride and the highest HDL-c/LDL-c, although no significant difference of plasma triglyceride had been found between the RO group and the LO group. Hepatic lipid content in fish fed diets with SO, RO, and LO was significantly higher compared with PO and FO groups. The higher activities of hepatic G6PD and ME were found in fish fed diets with PO or FO compared to LO. The relative expression of LPL, LXR, and ApoB-100 gene in the RO group and the LO group, MTP gene in the LO group, PPARα and FAS genes in the PO group, and PPARγ gene in the SO group were significantly higher than those in the FO group. These results indicated that the increase in hepatic lipid deposition of turbot induced by the SO, RO, and LO diets are associated with up-regulation of some genes involved in lipids biosynthesis metabolism.

Mercury levels of yellowfin tuna (Thunnus albacares) are associated with capture location

Mercury is a toxic compound to which humans are exposed by consumption of fish. Current fish consumption advisories focus on minimizing the risk posed by the species that are most likely to have high levels of mercury. Less accounted for is the variation within species, and the potential role of the geographic origin of a fish in determining its mercury level. Here we surveyed the mercury levels in 117 yellowfin tuna caught from 12 different locations worldwide. Our results indicated significant variation in yellowfin tuna methylmercury load, with levels that ranged from 0.03 to 0.82 μg/g wet weight across individual fish. Mean mercury levels were only weakly associated with fish size (R2 < 0.1461) or lipid content (R2 < 0.00007) but varied significantly, by a factor of 8, between sites. The results indicate that the geographic origin of fish can govern mercury load, and argue for better traceability of fish to improve the accuracy of exposure risk predictions.

Fitness consequences of habitat variability, trophic position, and energy allocation across the depth distribution of a coral-reef fish

Environmental clines such as latitude and depth that limit species’ distributions may be associated with gradients in habitat suitability that can affect the fitness of an organism. With the global loss of shallow-water photosynthetic coral reefs, mesophotic coral ecosystems (~30–150 m) may be buffered from some environmental stressors, thereby serving as refuges for a range of organisms including mobile obligate reef dwellers. Yet habitat suitability may be diminished at the depth boundary of photosynthetic coral reefs. We assessed the suitability of coral-reef habitats across the majority of the depth distribution of a common demersal reef fish (Stegastes partitus) ranging from shallow shelf (SS, <10 m) and deep shelf (DS, 20–30 m) habitats in the Florida Keys to mesophotic depths (MP, 60–70 m) at Pulley Ridge on the west Florida Shelf. Diet, behavior, and potential energetic trade-offs differed across study sites, but did not always have a monotonic relationship with depth, suggesting that some drivers of habitat suitability are decoupled from depth and may be linked with geographic location or the local environment. Feeding and diet composition differed among depths with the highest consumption of annelids, lowest ingestion of appendicularians, and the lowest gut fullness in DS habitats where predator densities were highest and fish exhibited risk-averse behavior that may restrict foraging. Fish in MP environments had a broader diet niche, higher trophic position, and higher muscle C:N ratios compared to shallower environments. High C:N ratios suggest increased tissue lipid content in fish in MP habitats that coincided with higher investment in reproduction based on gonado-somatic index. These results suggest that peripheral MP reefs are suitable habitats for demersal reef fish and may be important refuges for organisms common on declining shallow coral reefs.

Nghiên cứu sử dụng rong xanh (Cladophora sp.) làm nguồn thức ăn cho cá rô phi (Oreochromis niloticus)

The study was conducted to assess potential of using green seaweed (Cladophora sp.) as a feed for tilapia (Oreochromis niloticus). Seven feeding regimes were applied with triplicate tanks, and fish was fed daily either commercial feed or fresh/dried green seaweed: (1) single commercial feed daily as a control treatment, (2 and 3) single fresh/dried green seaweed everyday and 2 alternative feeding regimes where (4 and 5) 1 day commercial feed and 1 consecutive day fresh/dried green seaweed, (6 and 7) 2 consecutive days fresh/dried green seaweed. Fish with initial weight of 3.94±0.26 g was stocked in the 250L tanks at salinity of 10 ppt with continuous aeration. After 60 days of culture, survival of tilapia was not affected by the feeding treatments, and in the range of 93.3-98.3%. Growth rates of experimental fish fed alternative 1 day commercial feed and 1 day green seaweed were not significantly different from the control group (p>0.05). Application of alternative feeding regime, pellet feed could be reduced from 29.6% to 38.6% and water quality was better than compared with the control treatment. For proximate composition of fish muscle, the highest crude lipid content in fish fed commercial feed while the moisture, crude protein and ash contents had no influenced by feeding treatments. These results indicated that fresh/dried green seaweed can be used as a feed to partially substitute commercial feed for rearing tilapia which could contribute to save feed cost.

Polycyclic Aromatic Hydrocarbons (PAHs) and Organochlorinated Pesticides (OCPs) in Yellowtail (Seriola lalandi) from three Spatially Distinct Locations along the Coast of South Africa: Levels, Sources and Fish Size Effec

Polycyclic aromatic hydrocarbons (PAHs) and organochlorinated pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT), endosulfan and benzenhexachloride (BHC) were evaluated in yellowtail (Seriola lalandi) fish species. These hardous compounds were studied in fish sampled from three locations: Port Elizabeth, Yzerfontein and Struis Bay. The aim of the study was to investigate the profiles, levels and sources of PAHs and pesticides in yellowtail from the selected locations in relation to fish size and lipid content. Significant variations (p<0.05) were observed in the levels of PAHs measured in fish sampled from the three locations. Fish from Port Elizabeth had the highest PAHs concentrations (533.95 ± 34.36), followed by Yzerfontein (221.40 ± 33.03) and Struis Bay (88.97 ± 2.83) μg/kg wet weight. benzo(a)pyrene (as PAHs biomarker) exceeded the recommended EU limit (2 μg/kg) in samples from Port Elizabeth and Yzerfontein whereas samples from Struis Bay did not exceed. DDT was detected only in samples from Port Elizabeth and Yzerfontein with mean total concentrations (7.48 ± 5.18 and 11.14 ± 1.44 respectively) not significantly different. Fish size (weight) correlated positively with lipid content (0.65; p<0.01) and a stronger positive correlation with AE©PAHs (0.83; p<0.01). PAHs input source in fish from Port Elizabeth reflected a mixture of petrogenic and pyrogenic whereas, Yzerfontein and Struis Bay showed input source as petrogenic. In conclusion, consumption of large sized fish in locations with high PAHs burden can predispose consumers to health risk. Further investigation into human dietary exposure with the species is recommended.

Chicken Viscera Meal as a Main Component in Diet for African Catfish Clarias gariepinus (Burchell 1822) Reared in Earthen Ponds

The effects of replacement of fishmeal (FM) with chicken viscera meal (CVM) on growth, body composition and production of Clarias gariepinus fingerlings (initial body weight 11.3 ± 0.1 g) was studied for 90 days. Three isonitrogenous (43 % crude protein) and isoenergetic (20 KJ/g) diets were formulated to containing 0% (diet CMV0), 30% (diet CVM30) and 50% (diet CVM50) of chicken viscera meal (CVM), as FM replace. Diet CVM0, without CVM, acted as a control whereas the commercial diet coppens developed for C. gariepinus was used to validate the experimental design. Feed intake value (247.17-262.0 g) was similar in fish fed Coppens, CMV0 and CMV50, and significantly higher in fish fed CMV30 (p 0.05). Food conversion ratio (1.11-1.19) was significantly higher in fish fed CMV50 diets (p 0.05). Lipid content in fish fed with CVM-based-diets was significantly higher, whereas ash significantly decreased (p<0.05). The study demonstrated that up to 30 % of CVM could be incorporated in the diets of C. gariepinus without negative effects on growth and whole body composition. Therefore, we recommended that CVM could be used to partially replace the expensive and imported FM.

Dietary marine-derived long-chain monounsaturated fatty acids and cardiovascular disease risk: a mini review.

Regular fish/fish oil consumption is widely recommended for protection against cardiovascular diseases (CVD). Fish and other marine life are rich sources of the cardioprotective long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) eicosapentaenoic acid (C20:5 n-3; EPA) and docosahexaenoic acid (C22:6 n-3; DHA). The lipid content and fatty acid profile of fish, however, vary greatly among different fish species. In addition to n-3 PUFA, certain fish, such as saury, pollock, and herring, also contain high levels of long-chain monounsaturated fatty acids (LCMUFA), with aliphatic tails longer than 18 C atoms (i.e., C20:1 and C22:1 isomers). Compared with well-studied n-3 PUFA, limited information, however, is available on the health benefits of marine-derived LCMUFA, particularly in regard to CVD. Our objective in this review is to summarize the current knowledge and provide perspective on the potential therapeutic value of dietary LCMUFA-rich marine oil for improving CVD risk factors. We will also review the possible mechanisms of LCMUFA action on target tissues. Finally, we describe the epidemiologic data and small-scaled clinical studies that have been done on marine oils enriched in LCMUFA. Although there are still many unanswered questions about LCMUFA, this appears to be promising new area of research that may lead to new insights into the health benefits of a different component of fish oils besides n-3 PUFA.

Polybrominated diphenyl ethers (PBDEs) in Great Lakes fish: Levels, patterns, trends and implications for human exposure

Levels of polybrominated diphenyl ethers (PBDEs) were measured in edible portions of Great Lakes fish, with the goal of examining patterns/trends and evaluating implications for human exposure. A total of 470 fillets of 18 fish species collected from various parts of the Canadian waters of the Great Lakes between 2006 and 2013 were analyzed for 17 (expanded to 33 in 2009) PBDEs. For a limited number of species, fillet to whole body and fillet to eggs PBDEs were compared to examine pattern and concentration among tissue types. Levels and patterns of PBDEs varied dramatically within and among the 18 fish species. Bottom dwelling Common Carp (and White Sucker) exhibited the highest ∑PBDE levels (27–71ng/g). Lake Trout and Lake Whitefish from Lake Superior had higher levels than those from the other Great Lakes; otherwise the spatial trend was Lake Ontario≫Erie~Huron~Superior. The measured levels would result in restriction on consumption of only Common Carp from the Toronto waterfront area, which is in proximity to the most urbanised region on the Canadian side of the basin. Deca-BDE was the major congener in panfish, while BDE-47 was the major congener in top predators and its contribution to ∑PBDE increased with the contamination. Although ∑PBDE was related to fish length and lipid content when all measurements were pooled, the relationships were variable for individual sampling events (species/location/year). Whole body ∑PBDE for bottom dweller Brown Bullhead and Common Carp were 2.6–4.9 times greater and egg ∑PBDE for four fatty Salmon/Trout species were same to 6.5 times greater than the corresponding fillet concentrations. Levels of major lower brominated PBDEs appear to have declined in fish fillets by 46–74% between 2006/07 and 2012. Although PBDE in existing consumer items will remain in-use for a while, it will likely not result in appreciable accumulation of PBDEs in fish. Based on an overall assessment, regular monitoring of PBDEs in Great Lake fish can be replaced with targeted surveillance and focus can be shifted to other in-use flame retardants.

Persistent organic pollutants in selected fishes of the Gulf of Finland

Fish samples of Baltic herring, sprat, flounder, perch, salmon, and river lamprey were collected from the Gulf of Finland in 2013 and 2014 with the aim to get an overview of the occurrence of pollutants in fish caught in Estonian waters. The content of non-dioxin-like polychlorinated biphenyls (ndl PCBs), polybrominated diphenyl ethers (PBDEs), organic tin (OT) and perfluorocompounds (PFAS) are examined and discussed in the study. The results revealed that potentially higher content of organo-tin compounds, perfluorocompounds and polybrominated diphenyl ethers in Baltic herring, salmon and river lamprey may cause concern regarding human exposure. It is important to link pollutant content to lipid content of fish taking into account their seasonal variation in different age classes.

Dry whey meal as a protein source in practical diets for Nile tilapia, Oreochromis niloticus fingerlings

ABSTRACTThis study was conducted as a trial of using dry whey meal (DWM) as a substitute for fish meal (FM) in practical diets for Nile tilapia, Oreochromis niloticus. Triplicate fish groups were fed on five isonitrogenous (30.2%) and isolipidic (6.9%) diets. The control diet (D1) used FM as the sole protein source. In the other four diets (D2–D5), FM protein was substituted by 25, 50, 75, or 100% DWM. Fish (3.5 ± 0.1 g) were stocked at a rate of 20 fish per 100-L aquarium and fed one of the tested diets up to satiation twice daily for 12 weeks. Fish growth, feed utilization, protein efficiency ratio, apparent protein utilization, and energy utilization for fish fed DWM diets up to 75% FM (D2–D4) tended to be higher but were not statistically different than the control diet. No significant effect of diet was found in whole-body moisture, crude protein, and total ash contents. Whole-body lipid content in fish fed the 100% DWM (D5) diet was significantly higher than that for fish fed the control diet. The optimal replacement level of FM by DWM was estimated by second-order polynomial regression to be 62.5%.

Growth, Survival, and Body Composition of Transgenic Common Carp Cyprinus carpio 3rd Generation Expressing Tilapia Growth Hormone cDNA

Transgenic has been known as one of the applicable methods to improve growth performance of cultured fish. This study was performed to evaluate the growth performance, survival, and body composition of the 3rd generation of growth hormone (GH) transgenic common carp (TG). Juveniles (BW: 1.53 ± 0.03 g) were reared for 60 days in 250-L glass aquarium with stocking density of 25 fishes/aquarium. Fishes were fed with commercial feed (protein content 36%), three times a day to satiation. Growth and survival were measured every 20 days. Our results showed that TG fish has 1.49 times higher in average weight growth (p < 0.05) compared with the non-transgenic common carp (NT). Higher total feed consumption, survival, body protein content, protein and lipid retention, hepatosomatic index, and lower feed conversion ratio were also shown on TG fish compared with NT fish (p < 0.05). However, body lipid content and blood glucose level of TG fish were lower (p < 0.05) compared with the NT fish. Total ammonium nitrogen level in rearing media of TG fish was 51.78% lower (p < 0.05) than that of the NT fish. In conclusion, culturing of GH-TG common carp showed potential to achieve high productivity, efficient, and environmental-friendly aquaculture.

Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes

Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.

Effects of Artemia Salina Substitution by Maggot Meal on Growth Performance and Body Composition of Africa Catfish Heterobranchus Longifilis (Valenciennes, 1840) Larvae

Housefly Musca domestica larvae meal used as substitute of Artemia salina in catfish larvae diets has increased in recent researches. In this study, a feeding trial was conducted to determine the optimal level of Artemia meal substitution by maggot meal for Heterobranchus longifilis larvae growth. Four diets were formulated at 35% crude protein by replacement of Artemia meal by maggot meal of 25%, 50%, 75% and 100% in the control diet on protein based. Fish initial body weight of 0.0071 g were stocked at 1 larvae/L and fed ad libitum to triplicate groups three times a day for 49 days. Results revealed that all levels of dietary maggot meal inclusion have improved the larvae growth. Growth and survival parameters were better at 75% of Artemia meal replacement followed by 50%. At the end of the experiment, significantly highest carcass ash content was recorded with fish fed with 75% and 100% of maggot meal inclusion while the fish lipid content was higher in fish fed control diet at 25% and 50% of Artemia meal replacement. Present results showed that 75% of Artemia substitution in 35% protein diet was the best level to improve growth of Heterobranchus longifilis larvae without adverse effects on fish biochemical composition.

Interannual and Seasonal Dynamics in Lipidic Signatures of Trichiurus lepturus

ABSTRACTInterannual and seasonal (premonsoon, monsoon, and postmonsoon) variability in the lipid, fatty acids, and total cholesterol content of ribbon fish, Trichiurus lepturus were determined for a period of 4 years (2008–2011) along the southwest (SW) and southeast (SE) coasts of India. The lipidic compositions were studied along with chlorophyll-a concentration and sea surface temperature (SST) data obtained from MODIS and Sea WiFS. The lipid content shows seasonal fluctuations with higher values in the postmonsoon season along the SE coast and during the monsoon in the SW coast. Among polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA) dominated over eicosapentaenoic acid (EPA) throughout the seasons except in winter on the SE coast. The health indices such as atherogenic/thrombogenicity indices, total cholesterol, and hypocholesterolemic/hypercholesterolemic ratio of ribbon fish were found to be ideal, which contributed toward its parameters to be qualified as a potential health food.

Short-term fasting increases skeletal muscle lipid content in association with enhanced mRNA levels of lipoprotein lipase 1 in lean juvenile red seabream (Pagrus major)

Cultured fish are often subjected to short-term fasting for a few days prior to transport or slaughter. This intervention reduces waste and oxygen consumption during transport and improves flesh quality, but little is known about how it affects the muscle lipid content. Even less is known for wild-caught fish that are also sometimes fasted before slaughter. To investigate the effects of short-term fasting on muscle lipid content, we performed three fasting experiments using adult, lean juvenile, and fatty juvenile red seabream (Pagrus major). In the first experiment using adult specimens (performed at 20°C), fasting for 10days caused up to 2.3-, 7.8-, and 3.7-fold increases in muscle mRNA levels of lipoprotein lipase 1 (LPL1), LPL2, and peroxisome-proliferator-activated receptor gamma (PPARγ), respectively (n=6 each). These genes all participate in lipid accumulation. The second experiment was performed on 5 groups of lean juvenile red seabream [considered as wild-caught fish; 19°C, n=5 each except for one group (n=4)]. Fasting for 5days significantly increased muscle lipid content (percentage of wet weight) and LPL1 mRNA levels up to 2.2- and 11-fold, respectively. The mRNA levels of LPL2 and PPARγ could not be determined possibly due to their low expression levels. The lipid amount (mg) in the liver decreased by 88% during fasting, whereas adipose tissue apparently disappeared after fasting for 10days. These results suggest that lipid mobilization from liver and adipose tissue anticipated the muscular utilization of lipid, resulting in the counterintuitive increase in muscle lipid content during fasting. The third experiment was conducted on 7 groups of fatty juvenile red seabream [considered as cultured fish; 20°C, n=5 each except for one group (n=4)]. Fasting up to 10days did not increase muscle lipid content or LPL1 mRNA levels. The lipid amount in the liver, but not in the adipose tissue, decreased during the experiment. Fasting for 10days was not enough to induce active lipid mobilization when fish were well fed prior to fasting. Contrary to our expectations, regression analysis using data from juvenile specimens found a significant inverse relationship between LPL1 mRNA levels and lipid amount in the liver, which might indicate that LPL1 mRNA levels are a reflection of temporal tissue demand for lipids. Overall, these results suggest that short-term fasting for ~5days increases muscle lipid content of wild-caught lean fish possibly by an LPL1-dependent lipid transport mechanism. Statement of relevanceWe showed that short-term fasting improves flesh quality.

Optimal Dietary Protein and Lipid Levels for Growth of Juvenile Israeli Carp Cyprinus carpio

A feeding trial of four dietary protein levels (20, 30, 40, and 50%) and two lipid levels (7 and 14%) with a factorial design was conducted to determine the optimal dietary protein and lipid levels for juvenile Israeli carp Cyprinus carpio. Triplicate groups of fish (average body weight, 1.3 ± 0.02 g) were fed the experimental diets for 9 weeks. Survival of fish was not affected by either dietary protein or dietary lipid level. Weight gain and feed efficiency increased as dietary protein levels increased up to 40 and 50%, respectively. Weight gain was higher in fish fed the high-lipid diets with 20 and 40% protein content. Feeding efficiency increased as the dietary lipid level increased for the 30, 40, and 50% protein diets. Daily feed intake decreased with increasing protein level and the minimum feed consumption was observed in fish fed the 50% protein diet with 14% lipid content. Moisture and lipid contents of the whole body were affected by both dietary protein and lipid levels. The crude lipid content of fish fed the 14% lipid diet was higher than that of fish fed the 7% lipid diet at each protein level. The results of this study indicate that a diet containing 40% protein with 14% lipid content is optimal for the growth and effective protein utilization of juvenile Israeli carp.