Different phosphatidylcholine and n-3 HUFA contents in microdiets for gilthead seabream (Sparus aurata) larvae: effects on histological changes in intestine and liver

The aim of the present study was to study the effect of different dietary phospholipids derived from Krill (KPL) and soybean lecithin (SBL) with different levels of phosphatidylcholine (PC) and n-3 HUFA on the performance and histological changes in intestine and liver of seabream larvae. Sea bream larvae (16 dph) were fed for one month five microdiets formulated by using two different sources of phospholipids (Control, 7KPL, 9KPL, 7SBL and 9SBL). The larvae fed dietary KPL rich in phosphatidylcholine and n-3 PUFA showed better performance in terms of survival and growth than those fed SBL. The inclusion of KPL up to 7% PL (3.8% PC and 7.7% n-3HUFA) in diet was sufficient enough to significantly improve larval survival and growth compared to the highest dietary 9% PL of SBL (2.5% PC and 5.6% n-3HUFA) due to the higher content of PC and n-3 HUFA in dietary KPL. The larval performance in terms of survival and total length was positively correlated to dietary PC and n-3HUFA contents. Also, inclusion of SBL was associated with a higher relative accumulation of lipid droplets in the supranuclear zone of the enterocytes (intestinal steatosis) and in hepatocytes (hepatic steatosis) compared to larvae fed dietary KPL. The intestinal and hepatic steatosis were negatively correlated to dietary PC content. In conclusion, dietary 7 % KPL (3.8 % PC and 7.7% n-3 HUFA) improved significantly the larval performance and decreased significantly the intestinal and hepatic steatosis compared to SBL, denoting better dietary lipid absorption, transportation and energetic utilization