Effect of different dietary polar lipid levels and different n−3 HUFA content in polar lipids on gut and liver histological structure of gilthead seabream (Sparus aurata) larvae (original) (raw)
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Aquaculture Nutrition, 2001
Dietary supplementation of phospholipids seems to be extremely important to promote growth and survival in ®sh larvae. Several studies also suggest the importance of n-3 highly unsaturated fatty acids (HUFA) rich phospholipids to further enhance larval performance. In the present study, four dierent diets were formulated in order to compare the eect of total dietary polar lipid contents, of soya bean lecithin supplementation and of feeding n-3 HUFA in the form of neutral or polar lipids on ingestion and incorporation of labelled fatty acids in gilthead seabream larvae. These diets were prepared including radiolabelled fatty acids from palmitoyl phosphatidylcholine, glycerol trioleate, free oleic acid (FOA) and free eicosapentaenoic acid (FEPA) and were fed to 25 day-old larvae. The results of these experiments showed that the elevation of the dietary polar lipid levels signi®cantly improved microdiet ingestion, regardless of the origins of the polar lipids. This eect caused an improved incorporation of phosphatidylcholine fatty acids to the larval polar and total lipids (TL) as the dietary polar lipids increased. Nevertheless, a better incorporation of fatty acids from dietary polar lipids in comparison with that of fatty acids from dietary triglycerides into larval lipids was found in gilthead seabream, whereas a better utilization of dietary triglycerides fatty acids than dietary free fatty acids could also be observed. Besides, the presence of n-3 HUFA rich neutral lipids (NL) signi®canlty increased the absorption eciency of labelled oleic acid from dietary triglycerides, but the presence of n-3 HUFA rich polar lipids, particularly improved the incorporation of FEPA. This fatty acid was preferentially incorporated into larval polar lipids in comparison with FOA.
Recent advances in lipid nutrition in fish larvae
Fish Physiology and …, 2000
Due to the importance of dietary lipid utilization for larval rearing success, increasing attention has been paid during the last years to different aspects of larval lipid nutrition such as digestion, absorption, transport and metabolism, which are frequently studied by different research groups. The present study reviews the published information on these aspects, including some recent results obtained in our laboratory, that contribute to a better understanding of larval lipid nutrition.
Aquaculture, 2007
A growth depressing effect of high dietary neutral lipid levels in marine fish larvae has been reported. This may be a result of a decrease in the efficiency or activity of digestive enzymes, a reduction in absorption efficiency and/or a decrease in food intake. The present work reviews recent studies carried out on commercially valuable species (Atlantic herring, Senegalese sole, European seabass and gilthead seabream) that investigated the effects of neutral lipid level and lipid source (fatty acid composition) on some of these key factors influencing larval growth. The results seem to collectively indicate that lipid transport from the enterocytes into the body may be more problematic in larval stages dealing with high neutral lipid diets than lipolytic enzymatic capacity, although both factors are likely to intervene. In seabass, lipase activity was significantly affected by the source of dietary lipid but not by its dietary level. Lipid sources differing in chain length and degree of saturation of their fatty acids may thus affect the efficiency or synthesis of neutral lipase through effects on substrate specificity. Phospholipid digestion appears to be more efficient than that of neutral lipids, although neutral lipase synthesis might not be a limiting factor for larval growth. High neutral lipid larval diets result in the accumulation of large lipid droplets in the enterocytes, which may in turn reduce fatty acid absorption efficiency and ultimately larval growth. Nonetheless, not all fatty acids are equally affected and mechanisms of specific essential fatty acid absorption probably exist. Food intake in seabream larvae is not strictly regulated by total lipid content of the diet and lipid source may have an important role in controlling ingestion. Therefore, the neutral lipid level in diets for marine fish larvae has a significant impact in several factors influencing growth but clearly it cannot be dissociated of its fatty acid composition, which appears to play a central role on the nutritional and physiological effects of dietary lipid, at the ingestion, digestion and absorption levels.
Fish Physiology and Biochemistry, 1993
The present study tested the effect of dietary lecithin and exogenous lipase on the incorporation of oleic acid in the tissue lipids of gilthead seabream larvae (Sparus aurata). Two of four microdiets were prepared by the addition of [1 4 C]oleic acid as free fatty acid (FFA) to diets containing either 5% cuttlefish liver oil (CLO) or 5% soybean lecithin. Glycerol tri[l-1 4 C]oleate was similarly incorporated in two other diets identical in lipid (4% cuttlefish liver oil, 1% soybean lecithin) and non-lipid composition but differed in that one contained a supplement of 0.05% porcine lipase. The effect of these diets was tested by following the incorporation of the label (dpm/mg larvae DBW) in the neutral and phospholipid fractions of seabream larvae at four different ages (21, 27, 32 and 45 days after hatching).
The significance of lipids at early stages of marine fish: a review
Aquaculture, 1997
The present work reviews the significance of lipids at different early stages of marine fish larvae. Lipids in broodstock nutrition are considered to be important for the quality of the larvae. Lipids affect the spawning and the egg quality of many fish species and a deficiency in (n-3) highly unsaturated fatty acids (HUFA) in broodstock negatively affects fecundity, fertilization rate and hatching rate of the species studied. Lipids as a source of energy at the embryonic and larval stage (before first-feeding) are evaluated in relation to other sources of energy such as protein and carbohydrates. After hatching and prior to first-feeding, some marine species show a preference in catabolizing phosphatidylcholine, whereas phosphatidylethanolamine tends to be synthesized. The effect of long-term (LT) and short-term (ST) enrichment techniques on the lipid composition of rotifers has been documented using various marine oils/emulsions. The quantitative and qualitative lipid class and fatty acid composition of diets influenced the lipid and fatty acid composition of both LT-or ST-enriched rotifers. The nutritional improvement of Artemia is also important and may follow the general methods used for rotifers. The functions of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) during early stages of marine fish larvae are apparently different. High amounts of EPA in relation to DHA may create an imbalance in the structural composition of the phospholipids, which could affect the normal growth and the quality of the larvae. Turbot larvae tended to exhibit lower pigmentation success with lower DHA:EPA ratio in the total lipid fraction of the larvae, especially when the absolute amounts of EPA were high compared to those of DHA (in the total lipid and phospholipid fraction of the larvae). Considerable research is
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2006
Contrary to larval essential fatty acid (EFA) requirements, the effect of dietary neutral lipid supply has been little investigated in marine fish larvae. The present work investigates the effect of feeding Senegalese sole larvae on Artemia enriched with higher or lower doses of lipid emulsion. Two lipid sourcessoybean oil and fish oilwere compared. From 16 days after hatching (DAH) onwards, larvae were fed one of four experimental treatments: Artemia enriched on a high or low dose of soybean oil emulsion (HS and LS) or Artemia enriched on a high or low dose of fish oil emulsion (HF and LF). In terms of growth, the dietary lipid level did not have a significant effect while the soybean oil treatments induced a lower growth than the fish oil-enriched Artemia. The fatty acid (FA) composition of the larvae closely reflected the dietary quantitative and qualitative FA profile. Only slight dietary effects were noted in the activity of trypsin, lipase and alkaline phosphatase. A higher amount of lipid droplets was noticeable in the posterior intestine epithelia and in the hepatocytes of larvae fed Artemia enriched with higher lipid doses, while LS-Artemia induced the lower lipid accumulation on the basal zone of the enterocytes, in accordance with the lowest total lipid level measured in this treatment. These results suggest an important effect of dietary total lipid level on lipid accumulation in the enterocytes and on FA absorption. At 33 DAH a tube feeding trial was conducted with 14 C-labelled oleic acid (OA) or triolein (TRI), showing that the lower accumulation of lipid droplets in the larvae fed LS was associated with a significantly higher absorption and retention in the gut and body tissues of the TRI label. For OA no significant differences between treatments were found. TRI label was considerably more evacuated than OA, indicating that sole larvae may have a lower capacity to incorporate a triacylglycerol, which needs to be digested. Finally, OA appears to be preferentially utilized for energy production, accumulating more in larval tissues when absorbed in higher amounts.
Comparative study on the fatty acid and lipid composition of four marine fish larvae
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1992
Atlantic halibut (Hippoglossus hippoglossus L.), plaice (Pleuronectes platessa), cod (Gadus morhua) and turbot (Scophthalmus maximus) at hatching and prior to first feeding. 2. Total fatty acid content decreased in the four species with up to 50% reduction in one of the halibut groups. Docosahexanaoic acid (22:6 n-3) was especially utilized. 3. Low lipid utilization was found in turbot in relation to the other three species. 4. Water environmental temperature may explain some of the differences in the fatty acid utilization and the source of metabolic energy between cold water species (halibut, cod, and plaice) and temperate species (turbot), in the period from hatching to prior to first feeding. 5. Relative amounts of neutral lipids and phospholipids were similar in plaice, cod and halibut, approximately 25% and 75% of total lipids, respectively, and were approximately constant during the yolk-sac stage. Neutral lipids were dominant for turbot at hatching, accounting for 53-55% of the total lipids, while phospholipids predominated prior to first feeding, being 56-59%. 6. Phosphatidylcholine was catabolized in halibut, plaice and cod but not in turbot, while phosphatidylethanolamine tended to be synthesized in all four species.
Journal of Fish Biology, 1997
Two feeding experiments were conducted to evaluate the suitability of two commercial microdiets as a complementary food for the rearing of larval gilthead seabream Sparus aurata. The effect of these diets on growth, survival and total lipid composition, as well as the histological structure of the liver were examined. The results of the first trial highlighted water quality as an important factor for the survival of microdiet-fed larvae. An increase in water flow rate improved larval survival despite a reduction in live food supply. An effect of tank design on larval growth and survival was observed also and seems to be related with the light level inside the tanks; wider light grey tanks gave better results than narrower black ones. Microdiet feeding significantly improved larval growth and increased hepatocyte diameter and presence of PAS positive vacuoles suggesting an increased glycogen storage in comparison with that of larvae fed live prey only. Artificial diets provided the larvae with a higher amount of lipids and polyunsaturated fatty acids of the n-3 series, resulting in a higher DHA content in the total lipid of the larvae fed on microdiets.