The effect of temperature and dietary fat level on tissue lipid composition in Atlantic salmon (Salmo salar) fed wax ester‐rich oil from Calanus finmarchicus

Copepod oil (CO) from the marine zooplankton, Calanus finmarchicus, is a potential alternative to fish oils (FOs) for inclusion in aquafeeds. The oil is composed mainly of wax esters (WE) containing high levels of saturated fatty acids (SFAs) and monounsaturated fatty alcohols that are poorly digested by fish at low temperatures. Consequently, tissue lipid compositions may be adversely affected in salmon‐fed CO at low temperatures. This study examined the lipid and FA compositions of muscle and liver of Atlantic salmon reared at two temperatures (3 and 12 °C) and fed diets containing either FO or CO, supplying 50% of dietary lipid as WE, at two fat levels (～330 g kg^?1, high; ～180 g kg^?1, low). Fish were acclimatized to rearing temperature for 1 month and then fed one of four diets: high‐fat fish oil (HFFO), high‐fat Calanus oil (HFCO), low‐fat fish oil (LFFO) and low‐fat Calanus oil (LFCO). The fish were grown to produce an approximate doubling of initial weight at harvest (220 days at 3 °C and 67 days at 12 °C), and lipid content, lipid class composition and FA composition of liver and muscle were determined. The differences in tissue lipid composition between dietary groups were relatively small. The majority of FA in triacylglycerols (TAG) in both tissues were monounsaturated, and their levels were generally higher at 3 °C than 12 °C. Polyunsaturated fatty acids (PUFA), particularly (n‐3) PUFA, predominated in the polar lipids, and their level was not significantly affected by temperature. The PUFA content of TAG was highest (～26%) in the muscle of fish fed the HFCO diet at both temperatures. Tissue levels of SFAs were lower in fish‐fed diets containing HFCO than those fed HFFO, LFFO or LFCO, particularly at 3 °C. The results are consistent with Atlantic salmon being able to incorporate both the FA and fatty alcohol components of WE into tissue lipids but, overall, the effects of environmental temperature on tissue lipids were more pronounced in fish fed the CO diets than FO diets.     

Liver lipids of female Carcharias taurus (spotted raggedtooth) sharks: a comparison between seasons

Female raggedtooth sharks (Carcharias taurus) migrate from the waters off the eastern Cape past KwaZulu-Natal and up to southern Mozambique and then back on an annual basis. They mate off the KwaZulu-Natal coast, gestate the pups off Mozambique, then deliver same off the eastern Cape. Prior to mating, they hypertrophise their livers and store large amounts of lipid, then towards the end of gestation subsist on this stored lipid as well as using it to feed their pups in utero. Raggedtooth sharks are aplacental, and hepatic lipids provide nutrients to the pups via continued ovulation throughout pregnancy. The fact of the liver hypertrophy was well documented, but whether the nature of the stored lipid or the amount of lipid per Kg of liver changed with season was unknown. Samples from raggedtooth females caught throughout the year were analysed for their lipid and fatty acid contents and significant differences noted between lipid, but not fatty acid, concentration with certain seasons. Liver mass decreased from spring to winter (16.3–9.9 kg) as did lipid concentration (572–326 mg/g). Within the fatty acids, 22:6n3 was ±17%, 20:5n3 ±7%, total n3 ±30% and total n6 ±7%. Also, both total polyunsaturates (±36%) and total monounsaturates (±33%) were greater than the total saturates (±28%).     

Planktivorous vendace (Coregonus albula) utilise algae‐derived fatty acids for biomass increase and lipid deposition

Spatial and seasonal variation in the abundance and composition of phytoplankton and other basal resources (bacteria, terrestrial detritus) influence the availability of essential polyunsaturated fatty acids (PUFA) for upper trophic levels in lake food webs. We studied accumulation, composition and content of fatty acids in planktivorous vendace (Coregonus albula) muscle tissue during the summer feeding period (May to late September) in six boreal lakes. Vendace muscle fatty acid content increased from ~17.7 mg/g DW to ~28.1 mg/g DW from spring to summer, corresponding to a ~59% increase in total fatty acids. PUFA accounted for 45%–65% of all fatty acids, and the most abundant fatty acid was docosahexaenoic acid (DHA, 22:6n‐3). The DHA content remained relatively constant throughout the sampling period (~7–8 mg/g DW), but the proportion of DHA decreased from ~40% in spring to ~30% in summer and autumn. The decrease in DHA proportion was due to accumulation of other fatty acids, primarily C₁₈ PUFA (predominantly synthetised by algae) and monounsaturated fatty acids. A similar fatty acid accumulation pattern was observed in lipid storing copepods, an important prey for planktivorous vendace. The abundance of bacterial and terrestrial biomarker fatty acids in vendace muscle and prey items was low (<5% and <0.1% respectively). The increase in weight and the deposition of internal energy stores in vendace were achieved predominantly by algae‐based food chain. This has ecological implications, as vendace requires sufficient lipid stores for reproduction in autumn and survival over winter.     

Proximate Composition,Cholesterol, and Fatty Acid Content of Brown Shrimp (Crangon crangon L. 1758) from Sinop Region,Black Sea

Proximate composition, cholesterol, and fatty acid content of brown shrimp (Crangon crangon L. 1758) harvested from the Sinop region of the Black Sea in Turkey was determined. Crude protein, lipid, moisture, and ash contents were 18.47 ± 0.09 g/100 g, 0.95 ± 0.05 g/100 g, 79.21 ± 0.01 g/100 g, and 1.39 ± 0.01 g/100 g, respectively. Cholesterol content was 173.56 ± 0.24 mg/100 g. Fatty acid composition was 33.04% saturated (SFAs), 22.17% monounsaturated (MUFAs), and 29% polyunsaturated (PUFAs). Among the SFAs, palmitic acid (C16:0) was predominant at 20.69% of the total fatty acid composition. Oleic acid (C18:1) was the predominant MUFA (14.25%), and the highest PUFAs were eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3), contributing 41% and 32% to the total PUFA content of the lipids, respectively. Thrombogenicity (TI) and atherogenicity (AI) index values were 0.31 and 1.34, respectively. The highest essential amino acids were leucine, lysine, valine, and isoleucine; while the highest levels of non-essential amino acids were aspartic acid, glutamic acid, glycine, and alanine, respectively.     

Characteristics and Functional Properties of Ovary from Squid Loligo Formosana

The characteristics and functional properties of the ovary from Loligo formosana were studied. Moisture (72.07 ± 0.24%) was dominant, followed by protein (18.64 ± 0.51%) and carbohydrate (7.44 ± 0.2%). Ash (1.39 ± 0.03%) and lipids (0.46 ± 0.5%) were found as the minor constituents. Albumin (79.02 ± 0.79%) was the major protein of the squid ovary, followed by glutelin-1 (8.31 ± 0.62%) and globulin (6.68 ± 0.08%). Nevertheless, prolamin and glutelin-2 constituted approximately 1% of the total proteins. Based on the electrophoretic studies, albumin had the largest band intensity. The squid ovary was rich in non-essential amino acids (52.26%) and high in hydrophobic amino acids (48.03%). It was also rich in polyunsaturated fatty acid (PUFA, 43.76 ± 0.84%), followed by saturated fatty acid (SFA, 39.36 ± 0.12%) and monounsaturated fatty acid (MUFA, 12.94 ± 0.55%). Ovary lipids had a high amount of docosahexaenoic acid (C22:6) (28.59%). At pH 3, the squid ovary powder (SOP) had the maximum solubility (96.39%), whereas the lowest solubility (38.33%) was observed at pH 9. The foaming capacity and stability of SOP were increased with increasing concentration up to 8% (p < 0.05). The globulin fraction showed the higher foaming capacity, as compared to albumin and glutelin-1 fractions. The squid ovary had good nutritional value and possessed excellent foaming properties. Therefore, the squid ovary could serve as a novel food additive or ingredient.     

南极磷虾粉脂质及脂肪酸组成分析

为分析南极磷虾粉的脂质成分,实验采用薄层层析法分离制备不同脂质组分,通过酸甲酯化衍生结合气相色谱/质谱法对不同脂质的脂肪酸组成进行比较研究.结果显示:①南极磷虾粉中脂质丰富,总脂含量高达11.37％,且以甘油三酯、磷脂和游离脂肪酸为主,胆固醇含量较低;②总脂脂肪酸主要为C16:0、C18:1n-9、C18:1n-7、C20:5n-3和C22:6n-3,且C20:5n-3和C22:6n-3占总脂肪酸含量的30.67％,表明南极磷虾粉在脂质方面具有较高的营养价值和开发潜力.③不同脂质的脂肪酸组成差异显著,胆固醇酯和甘油三酯中饱和脂肪酸和单不饱和脂肪酸含量均显著高于游离脂肪酸和磷脂(P＜0.05);而游离脂肪酸和磷脂富含多不饱和脂肪酸,两者含量分别为48.50％和49.96％,远高于胆固醇酯和甘油三酯的13.11％和24.36％,具有显著差异(P＜0.05).     

Proximate Composition and Nutritional Quality of the Meat of the Squat Lobster Munida gregaria (Fabricius 1973)

ABSTRACT

The squat lobster Munida gregaria has been recognized as a potential resource in several countries. However, data about its composition and nutritional value are scarce. This study provides information about the nutrients and nutritional quality of M. gregaria meat. Meat yield, proximate composition, cholesterol content, and fatty acid (FA) and amino acid (AAs) profiles were analyzed, and nutritional quality indexes were estimated. The average meat yield was 9.93%. The yearly average of the proximate composition of the M. gregaria meat (g/100 g meat) was moisture = 77.6, protein = 13.7, lipids = 3.84, and ash = 2.19. The average annual cholesterol content was 6.60 mg/100 g. The predominant FA (%) was C20:5ω3 (23.6), followed by C18:1ω9c (20.9), C22:6ω3 (18.5), and C16:0 (16.3); the unsaturated fatty acids were 72.8% of the total FA. The main AAs (g/100 g protein) were glutamic acid (15.1), leucine (9.47), and aspartic acid (8.51). Regarding the nutritional quality, the polyunsaturated FA/saturated FA ratio (1.99), ω3/ω6 ratio (8.62), atherogenic index (0.26), thrombotic index (0.56), hypocholesterolemic/hypercholesterolemic ratio (4.07), and polyene index (2.58) showed that M. gregaria meat provides lipids that are beneficial to the human diet. Moreover, M. gregaria meat provides high-quality proteins, which are well balanced in their essential AAs composition.     

Effect of replacement of fish oil with camelina (Camelina sativa) oil on growth, lipid class and fatty acid composition of farmed juvenile Atlantic cod (Gadus morhua)

Camelina (Camelina sativa) oil was tested as a replacement for fish oil in diets for farmed Atlantic cod (Gadus morhua). Camelina differs from other plant oilseeds previously used in aquaculture with high lipid (40 %), α-linolenic acid (40 %), antioxidants and low proportions of saturated fats. Dietary treatments were fed to cod (19 g fish^?1 initial weight) for 9 weeks and included a fish oil control (FO), 40 % (CO40) and 80 % (CO80) replacement of fish oil with camelina oil. There was no effect of replacing fish oil with camelina oil included at levels up to 80 % on the growth performance. Cod fed CO80 stored more lipid in the liver (p < 0.01), including more neutral lipid (p < 0.05) and triacylglycerol (p < 0.05). Cod fed CO80 decreased in total polyunsaturated fatty acids (PUFAs) in muscle compared to CO40 and FO (p < 0.05), increased in monounsaturated fatty acids (p < 0.01), decreased in total ω3 fatty acids (FO > CO40 > CO80; p < 0.01) and increased in total ω6 fatty acids (FO < CO40 < CO80; p < 0.01). In the liver, long-chain (LC) PUFA such as 20:4ω6, 20:5ω3, 22:5ω3 and 22:6ω3 decreased when fish oil was removed from the diet (p < 0.05), and increased in 18-carbon fatty acids (p < 0.01). Camelina oil can reduce the amount of fish oil needed to meet lipid requirements, although replacing 80 % of fish oil reduced LC PUFAs in both tissues. A comparison of BF₃ and H₂SO₄ as catalysts to transmethylate cod liver and muscle lipids revealed small but significant differences in some fatty acid proportions.     

Fatty acids in muscle of wild and farmed red porgy, Pagrus pagrus

The total fat content and the fatty acids of total lipids (TL), phospholipids (PL) and triacylglycerols (TAG) were analysed in white muscle from wild and reared red porgy, Pagrus pagrus (L.). The fat percentage was higher in reared (3.03 ± 0.57%) (mean ± SE) than wild (0.65 ± 0.03%) fish. The fatty acid pattern of reared porgy TL reflected the diet's lipid. Wild red porgy showed higher levels of ω3 and ω6 polyunsaturated fatty acids (PUFA) than reared, but both the atherogenic index and the index of thrombogenicity were very low for both wild and reared red porgy. The lipid fractions showed that the PL were composed of very high levels of PUFA, especially 22:6ω3, and their composition seemed to be better regulated than the composition of TAG. TAG showed greater differences between wild and reared fish, presumably because they reflected the dietary content of lipids. PUFA were the principal component of wild red porgy TAG.     

The Effects of Season and Site of Catch on Morphometric Characteristics,Mineral Content,and Fatty Acids of Sardines (Sardina pilchardus) Caught on the Algerian Coast

The variation of morphometrics, mineral content, and fatty acid composition of sardines was determined in relation to season and site of catch in the Mediterranean Sea. Sardines were caught in two regions of the Algerian coast: Mostaganem and Béni-Saf. In both sites, the contents of phosphorus (223 and 211 mg 100 g^?1) and sodium (95 and 10 mg 100 g^?1) were higher in June than in February. Total lipid content was related to the season, being low in winter (2.9%) and high in summer (11.3%). The fatty acid composition shows a high content of polyunsaturated fatty acids (PUFA) dominated by n-3 fatty acids eicosapentaenoic acid (EPA C20:5 n-3; 10%) and docosahexaenoic acid (DHA C22:6n-3; 25%). However, the content of n-6 fatty acids was relatively low both in winter (3.4%) and summer (4.7%). The saturated fatty acid (SFA) content was appreciable in sardines, which range from 34% to 37% according to season. This is in agreement with the literature related to the Mediterranean sardine.     

红螯螯虾胚胎发育过程中的生化成分变化

采用生物化学方法对红螯螯虾胚胎发育过程中主要生化成分(糖类、蛋白质及氨基酸、脂类及脂肪酸)进行了测定和分析,以期了解胚胎形态发生与营养需求的关系.结果显示:红螯螯虾胚胎发育过程中糖类总体含量很低.总蛋白与总氨基酸(TAA)的含量在胚胎发育过程中均呈下降趋势.在必需氨基酸(EAA)中亮氨酸(Leu)和精氨酸(Arg)的含量较高,而在非必需氨基酸中谷氨酸(Glu)和天冬氨酸(Asp)的含量较高.总脂在胚胎发育过程中的含量总体呈下降趋势,其中性脂和磷脂的主要脂肪酸均为C16:0、C18:0 、C18:1ω9和C18:3ω3.研究认为:在红螯螯虾胚胎发育过程中,糖类主要参与多种特异复合物的合成以及甲壳构建,这些特异复合物在细胞分化中起着重要的信号传递作用.蛋白质和脂类都是红螯螯虾胚胎发育过程中主要的结构和能源物质,蛋白质主要在早期被利用而脂类主要在晚期起作用.饱和脂肪酸(SFA)和单不饱和脂肪酸(MUFA)(C16:0,C18:0,C16:1ω7 和 C18:1ω9)主要作为能源物质被消耗而高不饱和脂肪酸(PUFA)(20:5ω3和22:6ω3)在胚胎发育过程中对于构建细胞膜以及调节中枢神经系统的发育起重要作用.     

长江口雌性成体刀鲚不同组织的脂肪酸组成分析

刀鲚(Coilia nasus)是一种江海生殖洄游性鱼类,长江口是刀鲚重要的洄游通道。本研究首次关注洄游至长江口卵巢发育比较成熟的繁殖群体的营养状况,并比较分析了其不同组织总脂和脂肪酸组成,为探明长江口水域刀鲚繁殖群体的营养状况及繁殖性能提供参考信息。结果显示,肌肉、肝脏和卵巢中的水分含量依次降低,总脂含量依次增加。饱和脂肪酸(SFA)总量在肝脏中最高,肌肉中最低,3种组织间差异显著(P<0.05);单不饱和脂肪酸(MUFA)中C18:1n9c的含量最高,其在肌肉、肝脏和卵巢中的含量依次为(40.88±0.19)%、(35.06±1.84)%和(42.85±2.14)%,肝脏中含量显著低于其他2个组织(P<0.05);多不饱和脂肪酸(PUFA)、n3-PUFA及二十二碳六烯酸(DHA)含量在肌肉、肝脏和卵巢中依次升高,卵巢中的含量显著高于肝脏和肌肉(P<0.05),而后二者间的差异不显著(P>0.05)。肌肉、肝脏和卵巢中不饱和脂肪酸(UFA)/SFA的比值依次为2.35、1.67和4.49,n3-PUFA/n6-PUFA的比值依次为4.94、3.87和5.13...     

雌性成体点篮子鱼不同组织的脂肪酸组成分析

测定和比较了性腺发育至Ⅲ期的雌性成体点篮子鱼肌肉、肝脏和卵巢组织中总脂含量及其脂肪酸组成。结果表明:(1)肌肉、肝脏和卵巢中的总脂含量分别为(2.79±0.15)%、(12.78±1.30)%和(2.85±0.17)%。肌肉与卵巢间总脂含量差异不显著(P>0.05),肝脏总脂含量约为肌肉和卵巢总脂含量的6倍,呈显著性差异(P<0.05);(2)肝脏中SFA总量明显高于肌肉和卵巢,3种组织中SFA含量呈显著性差异(P<0.05)。单不饱和脂肪酸(MUFA)中,C18∶1ω9 c1(顺式)在3种组织中含量最高,肌肉、肝脏和卵巢中的含量分别为21.86%、23.66%和23.96%,肝脏与卵巢间无显著差异(P>0.05),而与肌肉间差异显著(P<0.05);多不饱和脂肪酸(PUFA)、3PUFA和6PUFA在卵巢中含量最高,其次是肌肉,肝脏中含量最低,且三者之间的差异显著(P<0.05)。     

Changes in proximate composition,lipid class and fatty acid profile in Greenshell™ mussels (Perna canaliculus) over an annual cycle

Greenshell? mussel (GSM, Perna canaliculus) is New Zealand's most important aquaculture species. This study looked at changes in the proximate composition, lipid class and fatty acid profile of male and female market ready mussels over a year from April 2016 through to March 2017. There were differences over the season as well as differences between male and female mussels. Winter GSM had lower lipid, carbohydrate and protein concentrations than other seasons. Female mussels had a higher lipid (on average 1.8 ± 0.5 g/100 g ww) and carbohydrate (on average 5.0 ± 1.1 g/100 g ww) compared with the males (lipid, 1.5 ± 0.4 g/100 g ww and carbohydrate 4.5 ± 1.2 g/100 g ww). The major differences observed between seasons in the omega 3 and fatty acids content of the GSM were driven by the fat content, with the highest fat content found in female mussels in the spring prior to spawning. The majority of lipids found in mussels are polar lipids. Overall, this study provides the most comprehensive data on the composition and the lipid content of GSM to date and provides solid base‐line data as the New Zealand GSM industry continues to improve their production procedures. The enhanced nutritional payload of mussels harvested outside of winter (particularly female mussels in spring) could drive a differentiated higher value mussel product.     

Fatty acid composition of female and male clams (Ruditapes philippinarum): energy intake and temperature reliance

We analysed the effect of temperature, coupled with food ingestion rate (IR), on the fatty acid (FA) profile of female and male clams conditioned in two groups: L (low IR at 14 and 18 °C) and H (high IR at 18 and 22 °C). Significant differences for group L, both 18L and 14L with low IR and slow gonadal development, owed to differences in energy balance between 18L clams (negative energy balance) and 14L clams (positive energy balance). Plasmalogens (DMA 18:0) and non‐methylene‐interrupted FAs might protect against reactive oxygen species and preserve the integrity of the cell membranes during food stress in 18L clams. Differences in composition for group H, both 18H and 22H with high food intake, positive energetic balance and complete and similar gonadal occupation index (GOI), probably owed to the greater energy levels at 18 °C than at 22 °C. Clams at 22 °C H increased the oxidation of short‐chained PUFA 18:3ω3 and 18:3ω6 to maintain the same GOI as 18H clams. Regarding the sexual differences, the greater accumulation of 20:5ω3 and 20:4ω6 in females might be related with oocyte maturation and release during spawning, while the greatest levels of 22:6ω3 in males might be involved in spermatocyte membranes synthesis.     

Interacting effects of dietary lipid level and temperature on growth, body composition and fatty acid profile of rohu, Labeo rohita (Hamilton)

Three isonitrogenous (320 g kg^?1 crude protein, casein and gelatine) semi‐purified diets with 80 (L8), 130 (L13) and 180 (L18) g kg^?1 lipid (sunflower oil at increasing levels and cod liver oil fixed at 50 g kg^?1) at three digestible energy levels (12 096, 13 986 and 15 876 kJ kg^?1 dry weight) and were tested, in triplicate, on rohu fingerlings (3.2 ± 0.08 g) at two different temperatures (21 and 32 °C). Fish were fed to apparent satiation, twice daily, at 09.00 and 15.00 h, 7 days a week for 56 days. Maximum growth was obtained at a lipid level of 80 g kg^?1 (L8) at 21 °C (439.37%) and 130 g kg^?1 (L13) at 32 °C (481.8%). In general growth rate was higher at 32 °C than at 21 °C at all lipid levels. Tissue monounsaturated fatty acid (MUFA) contents decreased with increasing lipid level at 32 °C, but the reverse occurred at 21 °C. At 21 °C, Polyunsaturated fatty acid (PUFA) level increased significantly (P > 0.05) over initial values, but was affected insignificantly by dietary lipid level. At 32 °C, fish fed diet L13 had more n‐3 fatty acid (FA) in liver and muscle than the other two dietary groups while at 21 °C, both liver and muscle FA profiles exhibited significant change (P > 0.05) in n‐3 and n‐6 FA content which corresponded to variation in percent addition of dietary lipid. However, n‐3/n‐6 ratio was higher for fish fed diet L13 at 32 °C and diet L8 at 21 °C and may be correlated with fish growth.     

Proximate,Fatty Acid,and Amino Acid Compositions of Fish Muscle and Egg Tissue of Hilsa (Tenualosa) ilisha

The total lipid profile including the fatty acid composition and amino acid composition in eggs of Hilsa (Tenualosa) ilisha was studied in comparison with its muscle tissue. The eggs contained 30.4% lipid (on dry basis), which was 1.2 times higher than that of the muscle tissue lipid. The major portion of the egg lipid was composed of wax ester (about 47.6%) followed by triacylglycerol (TAG), phospholipid (PL), and cholesterol. The muscle tissue lipid contained TAG as the major fraction (41.8 ± 1.48%). Total amount of polyunsaturated fatty acids (PUFAs) was about 43 ± 0.05% and 32.4 ± 0.24% in egg PL and body tissue PL fractions, respectively. Among fatty alcohols of egg wax ester, 16:0 alcohol is predominant (56.4 ± 3.02%). Both the egg and muscle tissues are rich in all essential amino acids. The results indicate that muscle and eggs from Hilsa are rich in essential amino acids, PUFA, and phospholipids which are essential for human health and membrane development.     

Nutritional evaluation of fatty acids for the open thelycum shrimp, Litopenaeus vannamei: II. Effect of dietary n-3 and n-6 polyunsaturated and highly unsaturated fatty acids on juvenile shrimp growth, survival, and fatty acid composition

This study evaluated the nutritional value of dietary n‐3 and n‐6 polyunsaturated fatty acids (PUFA) such as linoleic (LOA) and linolenic (LNA) acids, and highly unsaturated fatty acids (HUFA) such as arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids for juvenile Litopenaeus vannamei, based on their effects on growth, survival, and fatty acid composition of hepatopancreas and muscle tissue. Diets contained 5% total lipid. A basal diet contained palmitic and stearic acids each at 2.5% of diet. Five diets contained 0.5% dry weight of LOA, LNA, AA, EPA, or DHA. An additional diet evaluated HUFA in combination by supplementing at 0.5% of diet, a mixture of n‐3 HUFA. All HUFA showed higher nutritional value than PUFA for shrimp and produced significantly (P < 0.05) higher final weight, weight gain, and total lipid in shrimp muscle. Fatty acid profiles of shrimp tissues reflected the composition of the dietary lipids. In general, saturated fatty acids were more abundant in the neutral factions, while PUFA and HUFA were more abundant in the polar fractions of tissues. Under these experimental conditions, HUFA had much greater nutritional value than PUFA for juvenile L. vannamei; moreover, dietary requirements for PUFA were not demonstrated.     

Changes in lipid class and fatty acid composition of adult male Litopenaeus vannamei (Boone) in response to culture temperature and food deprivation

The effects of culture temperature and food deprivation on lipid class and fatty acid composition of adult male Litopenaeus vannamei (Boone) were investigated. Shrimp were maintained in recirculating seawater systems at temperatures of 26 and 32°C and fed 75% dry commercial feed and 25% fresh‐frozen squid for 42 days. Additionally, groups of fed and non‐fed shrimp were maintained at 26°C for 17 days. In shrimp fed at either 26 or 32°C, polar lipids were the main constituents of total identified lipid classes in muscle tissue (66–71%), while neutral lipids were more abundant in hepatopancreas (82–88%). Higher levels of triglycerides were observed in lipids of shrimp hepatopancreas kept at 32°C, but no other lipid class was affected by temperature. A significantly higher proportion of 22:6n‐3 was consistent in muscle and hepatopancreas polar and neutral lipids of shrimp maintained at 26°C. In response to food deprivation, the amount of polar lipids, but not neutral lipids, was reduced by approximately 28% in muscle tissue, whereas all lipid reserves were almost depleted in the hepatopancreas. The variable consumption of some individual fatty acids was observed in polar and neutral lipids of both tissues.     

A study of the arachidonic acid requirements of the giant tiger prawn, Penaues monodon

This study examined the dietary requirement of arachidonic acid (ARA) when that of linoleic acid (LOA), the natural precursor to ARA, was also satisfied with linolenic acid (LNA) and also with and without the other key dietary highly unsaturated fatty acids (HUFA). Growth by prawns fed diets supplemented with ARA was poorer than in diets where it was not present. Supplementation of ARA to diets with either optimized HUFA or just optimised poly unsaurated fatty acids (PUFA) (i.e. LOA, LNA) resulted in poorer growth. Growth was poorest by prawns (215 ± 13%) fed diets with ARA supplemented at 20% of the total fatty acids but including 7% LOA, 21% LNA and 4% of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Growth was best in prawns fed diets devoid of ARA but with 7% LOA and 21% LNA (350 ± 19%). Prawns fed the reference diet (348 ± 21%) and the other diet devoid of ARA but containing about 7% LOA, 21% LNA and 4% of both EPA and DHA (345 ± 18%) had similar growth. The growth responses were not effects of altered lipid or fatty acid digestibilities. Indeed supplementation of ARA to the diet marginally improved the digestibility of the total neutral lipid in the diet and the digestibilities of some other dietary fatty acids. The amount of lipid in the digestive glands of prawns fed with the diets was reduced by the inclusion of ARA in the dietary lipids. Composition of the lipids in the digestive gland (DG) of the prawns was almost directly related to the composition of their dietary lipids. The proportion of ARA in the total fatty acids increased with level of supplementation of dietary ARA. An increased level of dietary ARA reduced the proportion of EPA, DHA in the DG lipid and also the total n‐3 and n‐6 fatty acids in the DG lipid. The results of this study support that addition of ARA to the diet of Penaues monodon when the other key essential fatty acids (EFA) have been optimized, does not improve their growth performance. It is suggested that key cause for this response may lie in the importance of the balance of the n‐3 to n‐6 fatty acids in the diet of these animals.