Astaxanthin (AST), functioning as an efficient antioxidant and pigment, is one of the most expensive additives in shrimp feeds. How to improve the uptake efficiency of dietary astaxanthin into farmed shrimp is of significance. The present study investigated the effects of lysophosphatidylcholine (LPC), an emulsifier, on dietary astaxanthin efficiency, growth performance, body color, body composition, as well as lipid metabolism of juvenile Pacific white shrimp (average initial body weight: 2.4 g). Three diets were prepared: control group, the AST group (supplemented with 0.02% AST), and the AST + LPC group (supplemented with 0.02% AST and 0.1% LPC). Each diet was fed to triplicate tanks, and each tank was stocked with 30 shrimp. The shrimp were fed four times daily for eight weeks. The AST supplementation improved the growth of white shrimp, while LPC further promoted the final weight of shrimp, but the whole-shrimp proximate composition and fatty acid composition were only slightly affected by AST and LPC. The LPC supplementation significantly increased the astaxanthin deposition in the muscle. The LPC supplementation significantly increased the shell yellowness of both raw and cooked shrimp compared to the AST group. Moreover, the dietary LPC increased the high-density lipoprotein-cholesterol content but decreased the low-density lipoprotein-cholesterol content in the serum, indicating the possible regulation of lipid and cholesterol transport. The addition of astaxanthin significantly up-regulated the expression of npc2 in the hepatopancreas compared to the control group, while the addition of LPC down-regulated the expression of mttp compared to the AST group. In conclusion, the LPC supplementation could facilitate the deposition of dietary astaxanthin into farmed shrimp and further enlarge the beneficial effects of dietary astaxanthin. LPC may also independently regulate shrimp body color and cholesterol transportation. This was the first investigation of the promoting effects of LPC on dietary astaxanthin efficiency.

This study evaluated the effects of replacing fish meal (FM) with corn peptide (CP) in juvenile tiger puffer in indoor tanks. Four diets were formulated for a 53-day feeding trial: a control group (CP0), and diets with 5% (CP5), 10% (CP10), and 15% (CP15) CP replacing FM. Each diet was fed to triplicate tanks. No significant difference in weight gain was observed between CP5 and control (p > 0.05). However, when the CP inclusion level exceeded 10%, growth performance began to decline, with the CP15 group being significantly lower than the control. The feed intake was linearly increased by CP. The proximate body composition revealed no significant difference among treatments. The CP10 group showed significantly higher serum malondialdehyde content than the control. Significantly lower muscle fiber density was observed in CP10 and CP15 compared to the control. The taurine content was significantly reduced in CP10, while no significant differences were found for other amino acids. Compared with the control group, the CP5 group showed significantly elevated levels of free proline and glutamic acid. The intestinal expression of the peptide transporter gene pept1 was significantly up-regulated by CP. In conclusion, the appropriate inclusion level of corn peptide was 5% for juvenile tiger puffer.

Our previous studies found that lipid emulsifiers can promote the absorption and deposition of liposoluble pigments in shrimp. The present study aimed to further investigate the effects of liposoluble pigments lutein (LUT) and lycopene (LYC), and their combination with lysophospholipids (LPL), on the growth performance, body coloration, and lipid composition of Pacific white shrimp Penaeusvannamei. Five diets were formulated: a control diet (Control), Control + 0.02% lutein (LUT), Control + 0.02% lycopene (LYC), LUT + 0.1% LPL (LUT + LPL), and LYC + 0.1% LPL (LYC + LPL). The feeding trial lasted for 8 weeks. There were no significant differences in shrimp growth and body composition among all groups. Both LUT and LYC increased the redness (a*) and yellowness (b*) of cooked shrimp. LPL synergistically enhanced the pigmentation-improving effects of LUT but weakened those of LYC. Additionally, LYC decreased the redness and yellowness of raw shrimp. Both LUT and LYC reduced the contents of saturated fatty acids and EPA while increasing the DHA content; LPL further enhanced this modulatory effect. In conclusion, LPL acts synergistically with LUT to improve the body coloration and modify the fatty acid composition of Pacific white shrimp, but its effect with LYC is limited.

Bile acids are important for lipid digestion and metabolic regulation, but the roles of individual bile acids in crustaceans remain unclear. This study evaluated the effects of six dietary monomeric bile acids on growth and lipid metabolism in juvenile Pacific white shrimp. Juvenile shrimp (2.5 g) were fed a basal diet or the same diet supplemented with 0.04% bile acid (cholic acid, hyodeoxycholic acid, chenodeoxycholic acid, deoxycholic acid, ursodeoxycholic acid, or hyocholic acid) for 8 weeks. Each treatment was assigned to three replicate 100-L tanks, with 30 shrimp per tank. Dietary monomeric bile acids did not significantly affect growth performance, body composition, or muscle fatty acid composition. Compared with the control group, chenodeoxycholic acid, deoxycholic acid, and hyocholic acid significantly reduced the hemolymph triglyceride levels, while cholic acid, chenodeoxycholic acid, and hyocholic acid lowered the hepatopancreatic lipid levels. All bile acid treatments reduced the hepatopancreatic malondialdehyde content compared with the control group. Expression of genes related to bile acid transport, sterol metabolism, and lipid catabolism was generally upregulated by bile acids, indicating enhanced bile acid circulation and lipid turnover. In conclusion, monomeric bile acids mainly regulate lipid metabolism and oxidative status rather than directly promoting growth under the present dietary condition, with chenodeoxycholic acid, cholic acid, and deoxycholic acid showing relatively stronger effects.