Dietary neutral lipid level and source in Senegalese sole (Solea senegalensis) larvae: Effect on growth, lipid metabolism and digestive capacity

Abstract

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 sources -soybean oil and fish oil -were 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.

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…REQUIREMENT Fish probably have an absolute requirement for phospholipids (PL), mainly phosphatidylcholine (PC) and possibly phosphatidylinositol (PI) (Coutteau et al 1997). The most striking example of this is seen in some marine larvae where lipid droplets tend to accumulate, sometimes in livers (Salhi et al 1999), but most commonly in enterocytes upon feeding with artificial or supplemented live feeds (Deplano et al 1989;Geurden et al 1997;Salhi et al 1999;Morais et al 2006;. The cause appears to be linked to impaired enterocyte lipoprotein synthesis where PC (and apolipoproteins) is needed to form a coat around the absorbed TAG enabling it to be transported out of the cell.…”

Stocking density and sex influence individual growth of Senegalese sole (Solea senegalensis)

“…Following some promising trials in early 80s, rearing of S. senegalensis has succeeded in key points such as reproduction (Anguis and Cañavate, 2005), weaning (Cañavate and Fernández-Díaz, 1999;Engrola et al, 2009), or nutrition (Rønnestad et al, 2001;Aragão et al, 2003;Morais et al, 2006;Conceição et al, 2007). However, diverse growth performance and high size variability is still an important issue when rearing Senegalese sole in captivity (Dinis et al, 1999;Flos et al, 1995, Flos et al, 2001Rueda-Jasso et al, 2004).…”

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“…Lipids seemed to be absorbed mainly by the posterior intestine, similarly as described for turbot Scophthalmus maximus (Koven et al, 1994), for Senegal sole Solea senegalensis (Morais et al, 2006) and brill Scophtalmus rhombus (HacheroCruzado et al, 2009). In S. aurata larvae the supranuclear vacuoles observed are of protein nature (González de Canales García et al, 1997).…”