Nutritional Qualities of the Low-Value Bivalve Mollusks Paphia malabarica and Villorita cyprinoides at the Estuarine Waters of the Southwestern Coast of India

The bivalve mollusks Paphia malabarica and Villorita cyprinoides collected from the estuarine system located in the southwest coastal waters of India were evaluated for their nutritional composition. A balanced essential to nonessential amino acid ratio (> 1.0) with a greater quantity of sulfur-containing amino acids in these species demonstrated that they could provide well-balanced protein depositions. The n-3/n-6 polyunsaturated fatty acid ratio in P. malabarica was found to be greater than 2, and, therefore, can be considered as a healthy diet. The C₂₀–C₂₂ long-chain polyunsaturated n-3 fatty acids (for example, docosahexaenoic acid and eicosapentaenoic acid) accounted for more than 23% of the total fatty acid content in P. malabarica as compared to about 7% in V. cyprinoides. P. malabarica showed greater hypocholesterolemic/hypercholesterolemic ratio (1.7) and lesser atherogenicity (0.7), thrombogenicity (0.3) indices when contrasted with those in V. cyprinoides, thereby indicating the nutritional superiority of the former. A greater content of vitamin D₃ (> 150 IU), along with significant quantities of calcium and phosphorus (> 500 mg/100 g) in the clams, signified their importance in preventing osteoporosis. This study demonstrated the importance of bivalves, in particular, P. malabarica as a valued species for human consumption.     

Enrichment of C20-22 Polyunsaturated Fatty Acids from Refined Liver Oil of Leafscale Gulper Shark,Centrophorus squamosus

The C_20-22 polyunsaturated fatty acids (C_20-22 PUFAs), mainly eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), were concentrated from the refined liver oil of deep sea leafscale gulper shark, Centrophorus squamosus, by sequential processes of winterization, urea complexation, and argentation chromatography. Winterization at 4°C using acetonitrile as solvent showed significant reduction of the total saturated fatty acid content (12%) with a concomitant increase of polyunsaturated fatty acids (36.3%). The urea complexation process significantly enriched the total polyunsaturated fatty acids (49.5%), with a reduction in saturated fatty acids (83.9%). Silica gel based argentation chromatography further concentrated the esters of C_20-22 PUFA (>99 percent purity). Nuclear Magnetic Resonance spectroscopy was used as a chemical fingerprinting tool to study the enrichment of C_20-22 PUFAs at various stages of the purification process. An increase in the proton signal intensity at the olefinic region (at δ 4–6) and a decrease in the aliphatic signals (at δ 0.5–2) showed that the process successfully enriched the C_20-22 PUFAs.

Abbreviations: PUFA, polyunsaturated fatty acid; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; FAME, fatty acid methyl esters; SFA, saturated fatty acid; MUFA, monounsaturated fatty acid; NMR, nuclear magnetic resonance; GCMS, gas chromatography mass spectrometry; FFA, free fatty acid.     

Compartmental changes in the contents of total lipid, lipid classes and their associated fatty acids in developing yolk-sac larvae of Atlantic halibut, Hippoglossus hippoglossus (L.)

Total lipid, lipid classes and their associated fatty acids have been measured in whole halibut, Hippoglossus hippoglossus (L.) larvae and in dissected animals separated into yolk and body compartments. At hatching the larval body contained 17 μg ind^?1 of lipid (11% of larval body dry weight), while the yolk contained 190 μg ind^?1. Phosphatidylcholine (PC) accounted for 57% of total yolk lipids while phosphatidylethanolamine (PE), triacylglycerol (TAG), cholesterol and sterol ester (SE) accounted for 12%, 12%, 9% and 6% respectively. The main fatty acids in the PC fraction were 22:6n-3 (25.6 μg ind^?1), 16:0 (19.2 μg ind^?1) and 20:5n-3 (12.6 μg ind^?1). Between hatch and 200 day-degrees post hatch (D°PH) a net decline in total lipids of 29% was seen. There seemed to be some, but relatively minor, changes in the relative composition of lipids in the yolk throughout development, which are indicative of a non-selective endocytotic bulk uptake of lipids from the yolk. Towards first-feeding there was a selective catabolism of PC and a net synthesis of PE in the developing body, resulting in a shift in the lipid class composition in the body compared with that of the yolk. The fatty acids released from lipid hydrolysis were mainly used as energy substrates by the growing halibut larvae; 22:6n-3 was quantitatively one of the most important fatty acid fuel in energy metabolism. At the same time 38% and 23% of the 22:6n-3 released from PC was retained by the PE and neutral lipids in the growing larval body respectively. Except for 20:5n-3 (2%, 14%) no similar retention was seen in any of the other fatty acids. The observed net synthesis of PE in developing yolk-sac larvae of Atlantic halibut and the preferential retention of 22:6n-3 into it, increasing from 28% at hatching to 45% at 200 D°PH, may point to a high biological value of this compound.     

Effect of crude oil extracts from trout offal as a replacement for fish oil in the diets of the Australian native fish Murray cod Maccullochella peelii peelii

The efficacy of trout oil (TO), extracted from trout offal from the aquaculture industry, was evaluated in juvenile Murray cod Maccullochella peelii peelii (25.4±0.81 g) diets in an experiment conducted over 60 days at 23.7±0.8 °C. Five isonitrogenous (48% protein), isolipidic (16%) and isoenergetic (21.8 kJ g^?1) diets, in which the fish oil fraction was replaced in increments of 25% (0–100%), were used. The best growth and feed efficiency was observed in fish fed diets containing 50–75% TO. The relationship of specific growth rate (SGR), food conversion ratio (FCR) and protein efficiency ratio (PER) to the amount of TO in the diets was described in each case by second‐order polynomial equations (P<0.05), which were: SGR=–0.44TO²+0.52TO+1.23 (r²=0.90, P<0.05); FCR=0.53TO²–0.64TO+1.21 (r²=0.95, P<0.05); and PER=–0.73TO²+0.90TO+1.54 (r²=0.90, P<0.05). Significant differences in carcass and muscle proximate compositions were noted among the different dietary treatments. Less lipid was found in muscle than in carcass. The fatty acids found in highest amounts in Murray cod, irrespective of the dietary treatment, were palmitic acid (16:0), oleic acid (18:1n‐9), linoleic acid (18:2n‐6) and eicosapentaenoic acid (20:5n‐3). The fatty acid composition of the muscle reflected that of the diets. Both the n‐6 fatty acid content and the n‐3 to n‐6 ratio were significantly (P<0.05) related to growth parameters, the relationships being as follows. Percentage of n‐6 in diet (X) to SGR and FCR: SGR=–0.12X²+3.96X–32.51 (r²=0.96) and FCR=0.13X²–4.47X+39.39 (r²=0.98); and n‐3:n‐6 ratio (Z) to SGR, FCR, PER: SGR=–2.02Z²+5.01Z–1.74 (r²=0.88), FCR=2.31Z²–5.70Z+4.54 (r²=0.93) and PER=–3.12Z²–7.56Z+2.80 (r²=0.88) respectively. It is evident from this study that TO could be used effectively in Murray cod diets, and that an n‐3:n‐6 ratio of 1.2 results in the best growth performance in Murray cod.     

Antioxidative Status of a Nutrient Enriched Formulation of Perna viridis in a Time Series Shelf-Life Study

ABSTRACT

The freeze-dried concentrate of green mussel, Perna viridis, was added with naturally derived antioxidative oleoresins of rosemary and turmeric along with trace amounts of other natural additives to prepare different treatments and was subjected to accelerated shelf life study (50°C) to evaluate its oxidative stability. The total oxyradical scavenging activities of samples with higher concentrations of turmeric over rosemary demonstrated the prominent role of the turmeric extracts to arrest free radical chain reactions. Time dependent antioxidative status in relation to the nutritional compositions was evaluated to identify the oxidative changes for different treatments. The addition of natural additives with polyphenolic moieties in the treatments shielded the mussel’s unsaturated fatty acids against oxidation as evident by higher polyunsaturated fatty acids in the two treatments as compared to control after 90 days of accelerated shelf-life study. Higher n-3/n-6 ratios after 90 days’ storage were also observed in these treatments. A threshold level of combined turmeric (0.8 g/100 g) and rosemary (0.4 g/100 g) was sufficient for optimum antioxidant activity and to maintain nutritional composition of the green mussel extract at desired levels.     

Nutritional Quality and Safety of the Important Commercial Cuttlefish Sepia lycidas

Proximate composition, amino acid, fatty acid composition, and contaminants (As, Cd, Hg, and Pb) of the kisslip cuttlefish Sepia lycidas were determined and compared with the recommendations and maximum allowed levels. The ratio of essential amino acids (EAA) to nonessential amino acids (NEAA) was 0.82. All of the amino acid scores were > 100, except for valine (93), and the highest essential amino acid score was obtained for tryptophan (327). The fatty acids profile was dominated by polyunsaturated fatty acids (PUFA; 45.01% of total fatty acids), and docosahexaenoic acid (DHA; 24.54% of total fatty acids) was the dominant fatty acid. S. lycidas was rich in n-3 PUFA, and the ratio of n-3/n-6 PUFA was 2.48. Regarding contaminants, As, Cd, and Pb concentrations in S. lycidas were 2.2, 0.28, and 0.02 mg kg^?1, respectively. Moreover, Hg values were below the detection limit (0.01 mg kg^?1).     

Effects of salinity on the fatty acid compositions of total lipid and individual glycerophospholipid classes of Atlantic salmon (Salmo salar) and turbot (Scophthalmus maximus) cells in culture

Cells from a relatively stenohaline marine species, turbot (Scophthalmus maximus) (TF) and an anadromous species, Atlantic salmon (AS) were cultured in media supplemented with NaCl to produce OPs varying from 300 to 500 mOsm kg^–1 and the direct effects of OP (salinity) on the fatty acid compositions of the main glycerophospholipid classes were determined. The most dramatic effects of salinity on total lipid fatty acids were observed in polyunsaturated fatty acids (PUFA) in TF cells. There was a graded decrease in the percentage of 18:2n-9, and consequently total n-9 PUFA, and concomitantly increased percentages of both total n-3 and n-6 PUFA with increasing salinity. The increased n-3 and n-6 PUFA was due to significantly increased percentages of the major fatty acids in each of these groups, namely 22:6n-3 and 20:4n-6, respectively. The reciprocal changes in n-9 PUFA and n-3/n-6 PUFA in TF cell total lipid resulted in the percentage of total PUFA not being significantly affected by changes in salinity. The graded decrease in 18:2n-9 with increasing salinity in TF cells was observed in all the major glycerophospholipids but especially PE, PI and PS. Increasing salinity resulted in graded increases in the percentages of 22:6n-3 in PE and PS in TF cells. The quantitatively greatest increase in the percentage of n-6 PUFA in TF cells occurred with 20:4n-6 in PC, PE and PL. There were less significant changes in the fatty acid compositions of glycerophospholipids in AS cells. However, the proportion of total n-3 + n-6 PUFA in PE varied reciprocally with the proportion of dimethylacetals in response to salinity. Similar reciprocal changes between fatty acids in response to salinity were also evident in the quantitatively more minor glycerophospholipids PS and Pl. In PS, the percentage of 22:6n-3 was significantly lower at 400 mOsm kg^–1 whereas the proportion of total monoenes was significantly higher at that salinity. A similar inverse relationship between total monoenes and 20:4n-6 (and, to a lesser extent total saturates) in response to salinity was noted in PI. The results show that environmental salinity, without whole-body physiological stimuli, has direct effects on the fatty acid composition of major glycerophospholipid classes in fish cells and that these effects differ in cells from different fish speciesAbbreviations ANOVA analysis of variance - BHT butylated hydroxytoluene - BSA bovine serum albumin - DMA dimethylacetals - EMEM Eagle's minimal essential medium - FCS fetal calf serum - GC gas chromatography - HBSS Hank's balanced salt solution (without Ca²⁺ and Mg²⁺) - OP osmotic pressure - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography     

Nutritional Composition of Edible Oysters (Crassostrea madrasensis L.) from the Southwest Coast of India

ABSTRACT

Nutritional composition of edible oysters (Crassostrea madrasensis) from the wild and cultured growth habitats from the southwest coast of India were evaluated over 4 years (2008–2011) during the premonsoon season. The important nutritional qualities of this species have been correlated with chlorophyll-a concentration, sea surface temperature, and phytoplankton density in their growth environments. The higher proportions of total polyunsaturated fatty acids, eicosapentaenoic, and docosahexaenoic acids in the edible oysters collected from the wild habitats were significantly correlated with chlorophyll-a concentration revealing the role of the phytoplanktons to contribute to the occurrence of these vital fatty acids. The ideal atherogenic index (AI); thrombogenicity index (TI); hypocholesterolemic/hypercholesterolemic ratio (HH); and balanced quantities of vitamins, minerals, amino acids, and low cholesterol contents qualified C. madrasensis as a potential health food.     

Fatty Acid Profiles and Lipid Oxidation Status of Sun Dried,Deep Fried,and Smoked Sardine (Rastrineobola argentea) from Lake Victoria,Tanzania

Freshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constituting 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 µmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.     

Fatty Acid Profiles of Different Shrimp Species: Effects of Depth of Catching

The aim of this study was to investigate fatty acid profiles of different shrimp species caught from deep water and shallow water. The shrimp species investigated in the study were Aristeus antennatus, Aristeomorpha foliacea, Plesionica martia, Parapenaeus longirostris, and Plesionica edwardsi from deep water; and Metapenaeus monoceros, Penaeus semisulcatus, Penaeus kerathurus, and Penaeus japonicus from shallow water.

Fatty acid composition of shrimps varied. The main fatty acids were C18:1n9, C16:0, C25:6n3, C22:5n3, and C18:0. Saturated, monounsaturated, and polyunsaturated fatty acid (PUFA) contents of P. longirostris, P. edwardsi, and M. monoceros were markedly different, respectively. The ratio of n6/n3 of the edible tissue of M. monoceros was found to be 0.795, whereas this value was 0.152 in A. foliacea. Among the species studied, the highest docosahexaenoic acid + eicosapentaenoic acid value was found for P. kerathurus. The levels of PUFAs of shallow water shrimps (ranging from 33.44 to 42.77%) were found to be higher than those of deep water shrimps (ranging from 29.68 to 33.95%). Marine animals in the upper water layers gain nutrition through phytoplankton which provides n-3 PUFA depending on solar energy. Shallow water shrimp species provide a satisfying amount of PUFA.     

Salinity and Temperature Effects on the Lipid Composition of Mullet Sea Fry (Mugil cephalus, Linne, 1758)

A large part of the extensive aquaculture in Tunisia was based on the transfer of mullet fry from the marine coastal areas to the continental fresh water lakes, the aim of this work is the monitoring of the changes made in the lipid composition of Mugil cephalus fry according to salinity and temperature acclimation. Fish acclimated to 14 °C and 0.5 psu salinity, contained 55% less total fatty acid than those acclimated to the seawater at the same temperature. Low salinity induces an increase in the percentage of some polyunsaturated fatty acid such as the 22:5 (n-3), the 22:6 (n-3) and the 20:4 (n-6), as a result of change in the level of triacylglycerol content or the activation in the synthesis of those fatty acids. The transition of the acclimation temperature from 26 to 14 °C in seawater is followed by a 215% increase in the amount of total fatty acids in the fourth week of acclimation. The total fatty acid levels of all fish at 1 week were higher than most values at 4 weeks. There was an increase of polyunsaturated fatty acids percentages due to the decrease of the temperature at the low salinity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of dietary lipids on the fatty acid composition of triglycerides and phospholipids in tissues of white sturgeon

Eight purified diets were fed to juvenile white sturgeon, Acipenser transmontanus Rick, for 9 weeks to investigate the effect of dietary lipids on the fatty acid composition of phospholipids and triglycerides from muscle, liver and brain. The diets contained 150 g kg^?1 of oils from canola, corn, cod liver, lard, linseed, soybean, safflower, or a control mixture (corn oil/cod liver oil/lard, 1:1:1, by wt). Dietary lipids significantly (P≤ 05) affected the composition of tissue triglycerides and phospholipids. Tissue triglyceride fatty acid composition ranged widely, in parallel with the dietary lipids, while phospholipids changes were more conservative. Brain phospholipid fatty acid composition was less responsive to diet compared with that in muscle and liver. Considerable amounts of n-6 and n-3 long chain polyun-saturated fatty acids (> C₂₀) were found in triglycerides and phospholipids with all diets, demonstrating that white sturgeon can desaturate and elongate linoleic acid (18:2n–6) and linolenic acid (18:3n–3). Further, the products of the Δ6 desaturase, i.e. 18:3 n–6 and 18:4n–3, were relatively abundant in triglyceride, suggesting that the Δ6 desaturase might not be a limiting step in the process in white sturgeon. Nevertheless, accumulation of both EPA and DHA was greater in the sturgeon fed fish oil than those fed linseed oil, indicating that muscle triglyceride EPA and DHA levels are best enhanced by diets rich in preformed EPA and DHA.     

Growth response and fatty acid composition of juvenile red claw crayfish (Cherax quadricarinatus) fed different sources of dietary lipid

A study was conducted to determine the effects of different sources of dietary lipid that differ in fatty acid (FA) composition on growth, feed conversion ratio (FCR), survival, and whole‐body proximate and FA composition of juvenile red claw. Juvenile red claw (0.55 ± 0.02 g) were reared over a 12‐week period. Five practical diets were supplemented with 70 g kg^?1 oil (by weight) from either linseed oil (LO), canola oil (CAO), corn oil (CO), beef tallow (BT) or menhaden oil (MO) and formulated to contain 400 g kg^?1 crude protein. Red claw were fed three times daily (800, 1200 and 1600) to controlled excess. At the conclusion of the experimental period, there were no significant differences (P > 0.05) found in percentage survival and FCR among dietary treatments and values averaged 85.4% and 3.4, respectively. However, final mean weight and specific growth rate of red claw fed Diet 1 (LO) was significantly higher (16.44 g and 3.95% day^?1, respectively) compared with that of red claw fed Diet 4 (BT; 12.24 g and 3.43% day^?1, respectively), but not different from red claw fed the other three diets. Likewise, red claw fed Diets 1 (LO) and 2 (CAO) had significantly higher percentage weight gain (2990 and 2880%, respectively) compared with the BT diet (2124%), but not different from red claw fed Diets 3 (CO) and 5 (MO). Whole‐body fat and ash composition was significantly affected (P < 0.05) by source of added lipid, but no differences were found in whole‐body moisture and protein. Moreover, whole‐body FA composition showed differences among the varying oil sources and primarily reflected the FA in the diets. Results of the present study indicate that plant oils LO, CAO and CO rich in linolenic acid (18:3n‐3), linoleic acid (18:2n‐6) and oleic acid (18:1n‐9) perform as well as MO containing high levels of n‐3 highly unsaturated fatty acids eicosapentanoic acid (20:5n‐3) and docosahexaenoic acid (22:6n‐3) for juvenile red claw crayfish grown indoors lacking natural food items. Further, red claw fed a diet containing BT, which has a high percentage of saturated FA, performed poorly compared with LO and CO in regards to weight gain. It appears that juvenile red claw can be fed diets containing less expensive plant‐based oils with high levels of 18‐carbon unsaturated fatty acids. This could reduce diet costs for producers and allow for profitability.     

Efficient utilization of dietary lipids in Octopus vulgaris (Cuvier 1797) fed fresh and agglutinated moist diets based on aquaculture by‐products and low price trash species

The aim of this study was to evaluate growth, biochemical composition and dietary nutrients utilization in Octopus vulgaris fed on four diets based on bogue Boops boops, from different origin and in two presentations: fresh discarded bogue (aquaculture by‐product) (DB‐f), fresh wild bogue (low price trash species) (WB‐f), discarded bogue agglutinated moist diet (DB‐m) and wild bogue agglutinated moist diet (WB‐m). Diets based on DB showed higher lipid content (19–26% dw) than those based on WB (5–6% dw). Octopuses fed on DB‐based diets showed higher growth (1.5–1.9% day^?1) and higher protein efficiency ratio (0.64–0.69) than those fed on WB‐based diet (1.1–1.5% day^?1 and 0.36–0.37 respectively), which suggests good utilization of dietary lipids and also a possible protein sparing effect by lipids in O. vulgaris. Octopuses fed on diets presented fresh showed a higher growth (1.9–1.5% day^?1) and a higher feed efficiency (62–65%) than those fed on agglutinated diets (1.1–1.5% and 52–60% day^?1 respectively). Regarding fatty acids, the digestive gland clearly reflected dietary lipid and fatty acid profile, while muscle showed a more stable composition. Low dietary ARA content reflected in octopus tissues, especially in specimens fed on DB‐based diets, which did not seem to affect growth during the experimental period.     

Replacing dietary fish oil with increasing levels of rapeseed oil and olive oil – effects on Atlantic salmon (Salmo salar L.) tissue and lipoprotein lipid composition and lipogenic enzyme activities

Six groups of Atlantic salmon, initial weight 142 ± 1 g, were fed increasing dietary inclusion of rapeseed oil (RO) in a regression design and one group was fed a 50% olive oil/50% capelin oil diet. Fatty acid composition was measured in red and white muscle, liver, and fatty acid and lipid class composition was measured in plasma and in the lipoproteins; very low density lipoprotein, low density lipoprotein, high density lipoprotein and nonlipoprotein fraction after 22 and 42 weeks of feeding. Further, the activities of liver NADH‐isocitrate dehydrogenase (ICDH), malic enzyme, glucose‐6‐phosphate dehydrogenase (G6PDH) and 6‐phosphogluconate dehydrogenase were measured at each sampling point. After 42 weeks of feeding the experimental diets, the tissue and lipoprotein fatty acid composition was highly affected by dietary fatty acid composition. Regressions showed that 22:1n ? 11, 18:1n ? 9, 18:3n ? 3 and 18:2n ? 6 are readily metabolized in all tissues analysed. Further, 20:5n ? 3 seems to be metabolized in muscle and retained in liver. 22:6n ? 3 was selectively retained in all the analysed tissues, and with higher retention in liver and plasma with higher polar lipid/neutral lipid ratio compared to white and red muscle. Liver from salmon fed 100% RO showed decreased G6PDH and increased ICDH activities compared to the other dietary groups; however, no linear relationship related to increased RO inclusion was detected. The amount of plasma lipoproteins, liver monoene fatty acid level and lipogenic enzyme activity decreased from the autumn to the winter sampling with concomitant decrease in temperature.     

池塘底泥生物组成的季节性变化对刺参食物来源的影响

为分析刺参养殖池塘底泥生物组成的季节变化及其对刺参食物来源的影响,本研究于2012年5—12月以16:1(n-7)/16:0及EPA作为硅藻的特征脂肪酸标志,20:4(n-6)作为褐藻的特征脂肪酸标志,DHA及DHA/EPA作为鞭毛藻或原生动物的特征脂肪酸标志,18:1(n-7)及奇数碳和支链脂肪酸(oddbr FAs)作为细菌的特征脂肪酸标志调查了荣成靖海湾刺参养殖池塘底泥和刺参脂肪酸组成的季节性变化特征。结果显示,硅藻、褐藻、多种异养细菌及鞭毛藻或原生动物为底泥的主要组成生物,且各类生物组成的季节变化显著,其中硅藻的特征脂肪酸16:1(n-7)/16:0及EPA最高值出现在冬季,褐藻的特征脂肪酸20:4(n-6)含量为秋季最高,细菌的特征脂肪酸18:1(n-7)及(oddbr FAs)最高值出现在夏季,鞭毛藻或原生动物的特征脂肪酸DHA含量为冬季最高。相关性分析显示,刺参食物中的硅藻、鞭毛藻或原生动物和细菌主要来源于底泥。研究表明,刺参养殖池塘底泥中主要生物组成季节性变化显著,进而引起刺参食物来源的季节性变化。     

Nucleic acids and fatty acids of the common octopus, Octopus vulgaris, in relation to the growth rate

The aim of this study was to investigate changes in the ribonucleic acid (RNA)/deoxyribonucleic acid (DNA) ratio and the fatty acid composition of cultured Octopus vulgaris (50–750 g) in relation to recent (last 30 days) specific growth rate (SGR). Wild animals (80–500 g), collected in the field throughout the year (Aegean Sea, Mediterranean), were also examined for the aforementioned biochemical parameters. Octopuses were reared in a closed seawater system at three different temperatures (15, 20 and 25 °C). The octopuses were fed on squid (Loligo vulgaris). The cultured animals showed a high n‐3 (33–52.9%) and n‐6 (3.3–13.7%) polyunsaturated fatty acid content, but with a high variation for 22:6n‐3 [docosahexaenoic acid (DHA)], 20:5n‐3 [eicosapentaenoic acid (EPA)] and 20:4n‐6 [arachidonic acid (AA)]. The proportion of these fatty acids (% total fatty acids) and the RNA/DNA ratio were linearly (P<0.0001) related to SGR. Specifically, RNA/DNA (0.5–1.9) and AA (2.7–10.7%) increased, while EPA (10.4–19.7%) and DHA (20.8–31.9%) decreased, with increasing SGR (0.4–1.7% day⁻¹). The highest levels of SGR, RNA/DNA and AA were detected in small (50–150 g) octopuses reared at 20 and 25 °C and in large (500–750 g) animals reared at 15 °C. Similar RNA/DNA levels and fatty acid percentages were found in wild octopuses. It is concluded that RNA/DNA, DHA, EPA and AA could be used as biochemical indices for predicting the growth rate of O. vulgaris.     

Changes in some components of the muscle lipids of three freshwater fish species under natural extreme cold and temperate conditions

Fatty acid composition, conjugated linoleic acid and cholesterol contents in the muscles of three freshwater fish species (Barbus plebejus escherichi, Capoeta capoeta capoeta and Rutilus rutilus) were determined under natural extreme temperate (July) and cold (January) conditions. The aim of the study was to determine whether there were differences in these components of the muscle lipids among these three fish species under extreme natural conditions. Samples were analyzed using gas chromatography. Palmitic, oleic, docosahexaenoic and eicosapentaenoic acids were the predominant fatty acids in all fish in both months. The percentages of polyunsaturated fatty acids, n − 3 polyunsaturated fatty acids, n − 6 polyunsaturated fatty acids and eicosapentaenoic + docosahexaenoic acids in the muscle of B. plebejus escherichi and C. capoeta capoeta were significantly higher in January (P < 0.05) than in July. The ratio of n − 6 to n − 3 polyunsaturated fatty acids was lower than 0.60 in all fish species, with C. capoeta capoeta showing the lowest ratio in January (0.36). The levels of cholesterol and conjugated linoleic acid ranged from 103.46 to 150.10 mg/100 g oil and from 16.27 to 35.45 mg/100 g oil, respectively, for all samples in both months. There were no statistical differences in cholesterol levels among the three fish species in July and January. Conjugated linoleic acid contents were significantly higher in January in B. plebejus escherichi and C. capoeta capoeta. Of the three species tested, the extreme temperate and cold conditions affected B. plebejus escherichi the most.     

养殖博氏鱼芒肉营养成分的分析及评价

采用国家标准方法测定湖北英山博氏(鱼芒)肉一般营养成分、氨基酸、脂肪酸和矿物质元素含量.结果表明,博氏(鱼芒)肉中水分、粗蛋白、粗脂肪和粗灰分的含量分别为75.36％±1.07％、17.90％±0.43％、5.13％±0.18％和0.98％±0.09％;18种氨基酸总量为(69.01±0.07) g/100 g(干重),其中5种鲜味氨基酸占氨基酸总量的41.70％,8种人体必需氨基酸占氨基酸总量的48.68％,必需氨基酸与非必需氨基酸比值为95.06％;粗脂肪中含24种脂肪酸,油酸含量38.41％±0.29％最高,单不饱和脂肪酸含量占脂肪酸总量的42.68％±0.10％,n-6多不饱和脂肪酸与n-3多不饱和脂肪酸的比值为1.48;矿物质元素中钾含量最高,为(1 118.51±30.67) mg/100 g(干重),微量元素中,铁、锌含量最高,分别为(1.19±0.10)和(1.18±0.05)mg/100 g(干重).与其它鱼类相比,博氏(鱼芒)肉蛋白质质量较高,氨基酸组成比例均衡,富含n-3多不饱和脂肪酸,矿物质元素含量丰富,有较高的营养价值.     

Nutritional status of a nereidid polychaete cultured in sand filters of mariculture wastewater

This study examined the nutritional composition of the intertidal marine polychaete Perinereis helleri (Nereididae) when artificially cultured in sand filters treating mariculture wastewater. Moisture levels in harvested P. helleri ranged from 758 to 855 g kg^?1, and ash, from 23 to 61 g kg^?1 wet matter (WM). Stocking density and graded size after harvest significantly affected their composition. Higher total lipid contents were found in large (>0.6 g) P. helleri (16–19 g kg^?1 WM) and those grown at the lowest density (1000 m^?2: 18 g kg^?1 WM) than in small (≤0.6 g) ones (14 g kg^?1 WM) and those grown at the highest densities (4000–6000 m^?2: 13–16 g kg^?1 WM). Several fatty acids within a very broad profile (some 30 identified) reflected this pattern, yet their ARA/EPA/DHA ratios were relatively unaffected. Feeding the polychaete‐assisted sand filters (PASF) with fish meal to increase worm biomass productivity significantly increased their DHA content. Other components (e.g. protein, phospholipids, cholesterol, carbohydrate, amino acids, nitrogen, minerals and bromophenols) and nutritional factors (e.g. maturity, feeding seaweed and endemic shrimp viral content) were also investigated. Results suggest that PASF‐produced P. helleri have a well‐balanced nutritional profile for penaeid shrimp and fish broodstock.