Growth performance and fatty acid tissue profile in gilthead seabream juveniles fed with different phospholipid sources supplemented in low-fish meal diets

Abstract

The aim of the present study was to evaluate the phospholipid requirements for gilthead seabream, fed with low-fish meal diets. A 70-day feeding trial was performed to evaluate the dietary effects of marine versus plant-based phospholipid sources in low-fish meal diets on growth, body composition, liver, muscle and intestinal fatty acid profiles (polar and neutral), as well as liver morphology. Three levels of krill (marine) or soy lecithin (plant) as phospholipid source, at 0.53%, 1% and 2%, were supplemented in diets with 10% fish meal inclusion. The effects were compared to a high-fish meal diet (65%) as a positive control, and a low-fish meal diet without addition of phospholipids as a negative control. Growth, feed and protein efficiency parameters were improved by the addition of phospholipids in the low-fish meal diets, irrespective of the source, but all parameters were lower compared to the positive control. Krill phospholipid supplementation showed optimal results at 0.5% levels and soybean lecithin supplementation at 1% level. Significant differences by the phospholipid supplementation were found in both the neutral and polar lipid profile in the liver and muscle, while only in the neutral lipids in the intestine. Evaluation of liver histology indicated mild improvement of steatosis symptoms. Overall, our results indicate that phospholipid supplementation in low-fish meal diets can improve the growth and liver status in gilthead seabream juveniles.