Effects of docosahexaenoic, eicosapentaenoic, and arachidonic acids on the early growth, survival, lipid composition and pigmentation of yellowtail flounder (Limanda ferruginea): a live food enrichment experiment

The role of dietary ratios of docosahexaenoic acid (DHA, 22:6n−3), eicosapentaenoic acid (EPA, 20:5n−3) and arachidonic acid (AA, 20:4n−6) on early growth, survival, lipid composition, and pigmentation of yellowtail flounder was studied. Rotifers were enriched with lipid emulsions containing high DHA (43.3% of total fatty acids), DHA+EPA (37.4% and 14.2%, respectively), DHA+AA (36.0% and 8.9%), or a control emulsion containing only olive oil (no DHA, EPA, or AA). Larvae were fed differently enriched rotifers for 4 weeks post-hatch. At week 4, yellowtail larvae fed the high DHA diet were significantly larger (9.7±0.2 mm, P<0.05) and had higher survival (22.1±0.4%), while larvae fed the control diet were significantly smaller (7.3±0.2 mm, P<0.05) and showed lower survival (5.2±1.9%). Larval lipid class and fatty acid profiles differed significantly among treatments with larvae fed high polyunsaturated fatty acid (PUFA) diets having higher relative amounts of triacylglycerols (18–21% of total lipid) than larvae in the control diet (11%). Larval fatty acids reflected dietary levels of DHA, EPA and AA while larvae fed the control diet had reduced amounts of monounsaturated fatty acids (MUFA) and increased levels of PUFA relative to dietary levels. A strong relationship was observed between the DHA/EPA ratio in the diet and larval size (r²=0.75, P=0.005) and survival (r²=0.86, P=0.001). Following metamorphosis, the incidence of malpigmentation was higher in the DHA+AA diet (92%) than in all other treatments (50%). Results suggest that yellowtail larvae require a high level of dietary DHA for maximal growth and survival while diets containing elevated AA exert negative effects on larval pigmentation.     

三种海胆性腺总脂的脂肪酸组成的研究

本文采用了ＦＦＡＰ石英毛细和气相色谱柱,对光棘球海胆,虾夷马粪海胆及海刺猬的性腺中总脂的脂肪酸组成进行了研究。结果表明这几种海胆含有四十种以上的脂肪酸,分布十分相似。主要的ＨＵＦＡ为１８：４ｎ－３（３．２％－７．４）,２０：４ｎ－６（６．４％－１６．７％）及２０：５ｎ－３（６．６％－１２．１％）,并含有非常罕见的ｎ－５及ｎ－７烯酸。     

Dietary α‐linolenic acid affects lipid metabolism and tissue fatty acid profile and induces apoptosis in intraperitoneal adipose tissue of juvenile grass carp (Ctenopharyngodon idella)

A 56‐day feeding trial was conducted to elucidate the effects and mechanism action of dietary α‐linolenic acid (ALA, 18:3n‐3) on lipid accumulation and fatty acid profile of muscle, hepatopancreas and intraperitoneal fat (IPF) in juvenile grass carp using three isonitrogenous and isoenergetic semi‐purified diets containing 0.0% (control group), 1.0% and 2.0% ALA, respectively. The lowest intraperitoneal fat (IPF) ratio was found in 2.0% group. In the muscle, hepatopancreas and IPF, docosahexaenoic acid (DHA, 22:6n‐3) and eicosapentaenoic acid (EPA, 20:5n‐3) contents increased with the increase in dietary ALA. In the IPF, caspase 3, caspase 8 and caspase 9 showed the highest activities in 2.0% group, while the value of Bcl‐2/Bax (B‐cell leukaemia 2/Bcl‐2‐associated X protein) reached the lowest. Meanwhile, swelling of the IPF mitochondria was observed in 2.0% group. The gene expressions of fatty acid desaturase (FAD) and fatty acid elongase (ELO) in the hepatopancreas and muscle showed significantly higher levels in the treatment groups, whereas an opposite trend was existed in the IPF. Fatty acid synthase (FAS), sterol regulatory element binding protein‐1c (SREBP‐1c) in the IPF and hepatopancreas reached the lowest in 2.0% group. Overall, dietary ALA could promote n‐3 highly unsaturated fatty acids (HUFAs) synthesis and suppress the accumulation of lipid by decreasing the expression of related genes and promoting the apoptosis in IPF.     

Changing of fat content and fatty acid profile of reared pike (Esox lucius) fed two different diets

Fat content and fatty acid profile of two pike yearling groups grown on two different diets were compared. The groups originated from culture on artificial feed. One group (cultured pike fed first pellet then prey‐fish (PF)) was fed with natural food, live prey‐fish, while the other one (cultured pike fed exclusively pellet (PP)) by trout feed through a 3‐month experimental period. Growth of pike was lower with PP than with PF. The trout feed resulted in an increase of the fat content of fillet and the formation of abdominal fat depots. Feeding of natural food decreased the fat content. The proportion of the saturated fatty acids in fillet was higher in the (PF) group. The n‐6 fatty acids (arachidonic C20:4n‐6 and docosatetraenic C22:4n‐6 acids) were lowest in PP‐fed pike. Regarding total n‐3 fatty acids ratio there was no significant difference between the groups, but the level of α‐linolenic (C:18:3n‐3) acid showed significant difference among groups.     

Use of differently enriched rotifers,Brachionus plicatilis,during larviculture of haddock,Melanogrammus aeglefinus: effects on early growth,survival and body lipid composition

We evaluated the effects of enriched rotifers on growth, survival and on the lipid composition of haddock larvae. The treatments tested were (1) AlgaMac 2000^®, (2) AquaGrow^® Advantage and (3) Pavlova sp. paste and AlgaMac 2000^®. The treatments did not influence larval growth rate throughout the experimental period (P = 0.70). Larvae from all treatments grew approximately 8% of their dry weight per day between 1 and 29 days post hatch (dph). Treatment 3 resulted in the best survival, estimated to be 3 on a scale from 0 to 5, whereas for the two other groups the survival estimates were 0 and 2. Rotifers from treatment 1 had low sterol concentrations, high eicosapentaenoic acid/arachidonic acid ratio and their feeding resulted in high larval mortality. Rotifers enriched with Pavlova sp. had the lowest proportions of the sum of saturated fatty acids, docosahexaenoic acid and sum of ω3 and the highest proportions of the sum of monounsaturated fatty acids (ΣMUFA). This was partially reflected in larvae from treatment 3 in that they had the highest proportions of ΣMUFA and the lowest proportions of Σω3 (P < 0.0001 for both analyses). In addition, these larvae had the highest and lowest ΣC₂₀ and ΣC₂₂ polyunsaturated fatty acids (PUFA) respectively (P < 0.0001 for both analyses). We suggest that more research with ω3 and ω6 PUFA can lead to improvements in the rearing of haddock larvae produced in hatcheries.     

Apparent digestibility coefficient of protein and amino acids of acid, biological and enzymatic silage for Nile tilapia (Oreochromis niloticus)

Using the fish silage to partially replace proteic feedstuff in aquafeeds is an alternative to mitigate sanitary and environmental problems caused by the lack of adequate destination for fisheries residues. It would also lower feed costs, consequently improving fish culture profitability. However, using fish silages in aquafeeds depends on determination of its apparent digestibility coefficients (ADC). This work aimed to determining the ADC of crude protein and amino acids of acid silage (AS), biological silage (BS) and enzymatic silage (ES) for juvenile Nile tilapia (94.5 ± 12.7 g). The ADC_CP was: 92.0%, 89.1% and 93.7% for AS, BS and SE respectively. The average ADC of amino acids was: 91.8%, 90.8% and 94.6% for AS, BS and ES respectively. Results encourage the use of AS, BS and ES to partially replace protein sources in balanced diets for neotropical fish.     

食用油反式脂肪酸傅里叶红外光谱重组检测技术

以食用油、反式脂肪酸标样及矿物精油为试验材料,采用傅里叶红外光谱重组(SR-FTIR)技术检测食用油中反式脂肪酸含量,并与标准红外分析方法(SB-ATR-FTIR法)进行比较.结果表明:SR-FTIR模型反式脂肪酸含量预测值与实际加入量高度线性相关,斜率为1.02,标准差小于0.05;SR-FTIR模型的灵敏度要比标准方法模型高20余倍.     

鱼类解偶联蛋白（UCP）基因研究新进展

通过生理性解偶联调节氧化磷酸化效率可能是进化早期发展起来的一种普遍策略,对生命的存在至关重要. 解偶联蛋白（uncoupling protein,UCP）家族是位于线粒体内膜的转运蛋白,哺乳动物基因组中已发现5个成员,其中UCP1~UCP3紧密相关,而UCP4和UCP5（即BMCP1,brain mitochondrial carrier protein-1）与它们差异较大. UCP1~UCP4不仅在哺乳类、鸟类等恒温脊椎动物中普遍存在,而且在鱼类等变温动物中也被证实存在,但UCP5目前仅在哺乳类中被发现. 哺乳动物褐色脂肪组织的UCP1,介导呼吸链产生的质子梯度泄漏,使氧化产生的能量以热的形式散发,但鱼类等变温动物UCP1的功能尚待进一步研究确立. UCP2和UCP3在产热、控制活性氧生成、脂肪酸氧化以及肥胖、糖尿病的发生中均发挥重要作用,二者的转录调节较复杂. UCP4和UCP5与其他UCP关系较远,UCP4仅在脑中表达,而UCP5在脑中高表达,它们的功能还不十分明确,但研究表明很可能与UCP2和UCP3的功能相似.     

乳酸菌培养液中活菌数与吸光度的关系研究

通过平板计数法测定脱脂乳为培养基的发酵液中乳酸菌的活菌数,并测其对应的吸光度,研究两者之间的相关关系。结果表明:在发酵过程中以脱脂乳为培养基的发酵液中乳酸菌的活菌数与吸光度之间呈线性相关关系。因此,通过测定发酵液的吸光度可以评定发酵乳制品中乳酸菌的活菌数。     

HPLC紫外法同时检测生鲜乳中环丙沙星和恩诺沙星残留

[目的]建立能同时检测环丙沙星和恩诺沙星残留的HPLC紫外检测法。[方法]采用10%三氯乙酸为提取液,直接从生鲜乳中提取环丙沙星和恩诺沙星,并进行HPLC检测。[结果]环丙沙星和恩诺沙星的最低检测限为5μg/L,在10~200μg/L浓度范围内呈良好的线性关系(r0.99),平均回收率为84%~112%,变异系数均小于5%。[结论]该方法不仅除蛋白和脂肪效果好,而且回收率较为理想,可以很好满足确证方法的要求,且重现性好。