Influence
of dietary polar lipids’ quantity and quality on ingestion and
assimilation of labelled fatty acids by larval gilthead seabream
Abstract:
Dietary supplementation of phospholipids seems to be
extremely important to promote growth and survival in fish 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 different diets were formulated in order to compare the
effect 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 palmityl 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 significantly improved microdiet ingestion,
regardless of the origins of the polar lipids. This effect 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) significanlty increased the absorption efficiency 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.
(Grupo de Investigación en Acuicultura, ILPGG &
ICCM, P.O. Box 56, E-35200, Las Palmas, Spain)