Effect of soybean phospholipid supplementation in formulated microdiets and live food on foregut and liver histological changes of Pelteobagrus fulvidraco larvae

The effect of supplementation of soybean phospholipid (PL) to Pelteobagrus fulvidraco larvae diets on growth and histological changes in intestine and liver were investigated. P. fulvidraco larvae were fed from day 6 to 21 posthatch with four diets containing the same basal diet, coated with different lipid fractions (6% diet). The lipid fractions consisted of increasing levels of soybean PL (0, 2, 4 or 6% of diet) and decreasing levels of mixed oil (fish oil:soybean oil, 2:1). A group of larvae was fed rotifers as a control. The body weight and total length of larvae increased as a result of PL supplementation. Larvae fed diet supplemented with 6% PL exhibited the best growth performance and similar to those fed rotifers. Larvae fed 6% PL and larvae fed rotifers had normal appearance of enterocytes and liver. The addition of PL to the diet caused a reduction in the degree of lipid accumulation and an increased number of goblet cells in the enterocytes of the anterior intestine. The degree of lipid accumulation in the anterior intestine and in the liver on day 21 was lower than that on day 14, which indicated that the ability of PL synthesis was enhanced as the fish aged. These results confirm that PL has a growth-promoting effect and indicate that soybean PL is suitable as a lipid and PL source in microdiets for P. fulvidraco larvae feed.