Title of the article：Effects of the supplementation of lysophospholipid in low-lipid diets on juvenile Pacificwhite shrimp

                                     Publication time：November 2024

                                     Publish journal：Aquaculture Researc

Abstract  

The shortage of lipid sources has been a limiting factor of the aqua-feed industry. Lysophospholipid (LPL) is a highly efficient lipid emulsifier, which may help improve lipid utilization efficiency and thus spare the dietary lipid. This study aimed to evaluate the effects of LPL on growth performance, fatty acid composition, and lipid metabolism of juvenile Litopenaeus vannamei (averagely, 2.4 g). Five diets were prepared: a control diet with 6.5% lipid, the control diet supplemented with 0.05% or 0.1% LPL (0.05% LPL and 0.1% LPL), a moderately low-lipid (MLL) diet supplemented with 0.05% LPL (0.05% LPL-MLL), and an extremely low-lipid (ELL) diet supplemented with 0.1% LPL (0.1% LPL-ELL). Each dietary group had triplicate tanks (30 shrimp in each tank). The feeding experiment lasted 8 weeks. Compared with the control group, the addition of 0.05% LPL promoted the growth by 9.95%; diet 0.05% LPL-MLL resulted in a comparable growth to the control, but diet 0.1% LPL-ELL tended to adversely affect the growth. Dietary LPL had little effect on the whole-body proximate composition. The content of 18:2n−6 and 18:3n−3 was significantly higher in the 0.05% LPL group compared to the control. The 20:5n−3 content was the highest in the 0.05%LPL-MLL group. In addition, the 0.05% LPL and 0.1% LPL group increased the plasma high-density lipoprotein-cholesterol content. Meanwhile, all LPL groups reduced the low-density lipoprotein-cholesterol content. The addition of LPL significantly regulated the messenger RNA (mRNA) expression of genes related to cholesterol homeostasis, such as ldlr, srb1, abca1, and abcg8. In conclusion, dietary supplementation with 0.05% LPL tended to promote shrimp growth and can spare 15% dietary lipid. However, when the dietary lipid content decreased from 6.5% to an extremely low level of 4.8%, dietary LPL was ineffective to spare lipids. This was the first study to validate the lipid-sparing effect of dietary LPL in shrimp.

Result

1.Compared with the control group, the 0.05% LPL group increased weight gain by 9.95%, while the 0.1% LPL-ELL group decreased weight gain by 11.34%.

图1 实验对虾的增重（平均值±标准误）。

Figure 1: Weight gain of experimental shrimp (mean ±SE)

2.There was no significant difference in body composition among the groups, indicating that the addition of LPL did not affect the protein and fat content of whole shrimp even under low-fat conditions.

3. The content of 20:2n-6, n-6PUFA, and 18:3n-3 in the muscle of the 0.05% LPL-MLL group significantly increased, and the content of 20:5n-3 significantly increased; The levels of 22:1n-9, 18:2n-6, 20:2n-6, n-6 polyunsaturated fatty acids (PUFAs) and 18:3n-3 in the muscles of the 0.1% LPL-ELL group were significantly reduced, while the levels of 20:3n-3 and the n-3/n-6 ratio were significantly increased.

4.The HDL-C content in the 0.05% LPL group was significantly higher than that in the low-fat group. Adding LPL can reduce plasma LDL-C and MDA content, and the control group was significantly higher than the 0.05% LPL-MLL group.

                                                                                                                                                      FIGURE 2: Biochemical parameters in the plasma of experimental shrimp (mean±SE).

Data bars not sharing the same letter on top were significantly (P<0:05)

(a) HDLC:high-density lipoprotein cholesterol;

(b) LDL-C: low-density lipoprotein cholesterol;

(c)MDA: malondialdehyde.

5.The MDA content in each LPL group in the liver was significantly lower than that in the control group.

FIGURE 3:The level of malondialdehyde in the liver of experimental shrimp (mean±SE）

Data bars not sharing the same letter on top were significantly (P<0:05)

6.The expression level of abca1 in the 0.1% LPL group was significantly lower than that in the control group and the 0.05% LPL-MLL group. The expression of abcg8 in the 0.1% LPL group and 0.1% LPL-ELL group was significantly lower than that in the 0.05% LPL group. The expression of ldlr and srb1 in the 0.1% LPL-ELL group was significantly lower than that in the control group.

 Conclusion:

The supplementation of 0.05% LPL can spare 1% lipid in the diet, but this lipid-sparing effect was not effective when the dietary lipid was reduced from 6.5% to 4.8% (of dry matter). Dietary LPL had only slight effects on the proximate and fatty acid composition of the shrimp body. Diet LPL may have the potential to regulate cholesterol transport and antioxidant capacity.