Search

This study was carried out to investigate the effects of five formulated feeds with different lipid sources (colza oil (CO), fish oil (FO), linseed oil (LO), soybean oil (SO), or palm oil (PO)) and kelp (Laminaria japonica) on the growth, reproductive performance of broodstock, and early larvae quality of sea urchin (Strongylocentrotus intermedius). The experimental diets were randomly allocated to a total of 48 (eight urchins per experimental group) individually cultured S. intermedius(initial weight 90.51 ± 0.82g) and the feeding period lasted for 12 weeks. The results showed that the weight gain rate of female sea urchins fed kelp was significantly higher than those fed formulated feeds while the gonadosomatic index of spawned female sea urchins fed kelp was significantly lower than those fed formulated feeds.S. intermedius broodstock fed FO showed the largest egg diameter and fecundity, which could be due to the abundant n-3 LC-PUFA deposited in the gonads of this group. Sea urchins fed SO showed the lowest fecundity and hatching rate, and the highest inflammation level. Sea urchins fed CO showed the highest content of oleic acid in the gonads and eggs, but the lowest fertilization rate. The highest hatching rate was observed in the kelp treatment, which was comparable to that in the LO and PO but was significantly higher than that in CO, FO, and SO. Before mouth opening, all prismatic larvae showed no significant differences in survival during the first 2 days post hatchery (DPH). At the 3 DPH, the survival of S. intermedius larvae was highest in the FO group, followed by those in the PO group, with the lowest survival observed in the kelp group. Thus, FO was accepted as the most ideal lipid source based on growth, reproductive performance, and early larval quality. These results could contribute to adopting an efficient feeding strategy to promote the reproductive performance and offspring quality by choosing the optimal lipid source for S. intermedius broodstock.

This study was conducted to investigate the effects of soya lecithin (SL) addition on the growth, antioxidant capacity, gonad development and nutritional quality of adult sea urchin (Strongylocentrotus intermedius). Five palm oil (PO)-based feeds were formulated with graded addition of SL (0%, 1.5%, 3%, 4.5%, and 6%). Fish oil (FO)- based feed (6% fish oil + 0% SL) and fresh kelp (Saccharina japonica) were used as the control diets. Each diet was randomly assigned to ten cages of sea urchins. The feeding experiment was performed in autumn season and lasting for 30 days. The results showed that the weight gain rate and gonadosomatic index were decreased due to moderate or higher addition level (3–6%) of SL. A low dosage (1.5%) of SL resulted in the most ideal attractive color and antioxidant capacity. The promoting effects of SL on the gonad development were observed at a low dosage, and were reflected by more sperm, larger oocytes and a thicker oocyte layer. However, the promoting effects of SL on gonad development were eliminated as the addition level increased to 4.5%. Male S. intermedius fed 1.5% SL showed comparable gametogenesis (stage III) to that of males fed FO and kelp. However, female S. intermedius fed formulated feeds showed markedly slower gonad development than those fed kelp, with all individuals staying in stage I and II. The deposition of arachidonic acid (ARA, 20:4n-6) increased while eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and n-3/n-6 polyunsaturated fatty acid (PUFA) decreased as the SL addition increased. Although FO resulted in the highest growth rate and LC-PUFA deposition, it negatively affected the antioxidant capacity. In conclusion, the optimal SL requirement was recommended to be no more than 1.5% in the PO-based diets for adult S. intermedius from the perspective of growth, antioxidant capacity, gonad development and nutritional quality. PO based diets showed comparable effects to FO based diets on the growth performance and gonad development. These results can contribute to optimization of the feed formulation for producing S. intermedius gonads that are high in quantity and quality.