Effects of Dietary Chenodeoxycholic Acid Supplementation in a Low Fishmeal Diet Containing Clostridium autoethanogenum Protein on Growth, Lipid and Cholesterol Metabolism, and Hepatopancreas Health of Litopenaeus vannamei

SIMPLE SUMMARY: Due to the scarcity of fishmeal resources, alternatives that provide the necessary nutrients for Litopenaeus vannamei are being sought. While fishmeal has been the main nutrition source of Litopenaeus vannamei due to its rich nutrients, the search for protein sources to replace it is becoming increasingly important. The protein derived from Clostridium autoethanogenum protein shows great potential as a substitute for fishmeal owing to its exceptional nutritional value. However, previous studies have suggested that the growth of Litopenaeus vannamei may be adversely affected by the fishmeal replacement of Clostridium autoethanogenum protein. Research has demonstrated that chenodeoxycholic acid can improve the growth and intestinal health of Litopenaeus vannamei. Five diets were formulated with varying concentrations of chenodeoxycholic acid to feed Litopenaeus vannamei. The results revealed that replacing partial fishmeal with Clostridium autoethanogenum protein and adding 0.06% chenodeoxycholic acid led to significant improvements in the growth performance, lipid metabolism, and sterol metabolism. Additionally, the hepatopancreas health of the Litopenaeus vannamei was also improved. The conducted experiment has set the groundwork for further investigation into determining the most effective quantity of chenodeoxycholic acid to be utilized in low fishmeal diets. ABSTRACT: The study aimed to assess the impact of adding chenodeoxycholic acid (CDCA) to the diet of Litopenaeus vannamei on their growth performance, lipid and cholesterol metabolism, and hepatopancreas health while being fed a low fishmeal diet. Five diets were formulated, one of which contained 25% fishmeal (PC); fishmeal was partially replaced with Clostridium autoethanogenum protein in the remaining four diets and supplemented with 0, 0.03, 0.06, and 0.09% CDCA (NC, BA1, BA2, and BA3, respectively). In this study, four replicates of each diet were assigned and each replicate consisted of 30 shrimp with an average weight of (0.25 ± 0.03 g). The shrimp were fed four times a day for a period of 56 days. The results of this study indicate that the inclusion of CDCA in the diet had a positive impact on the growth performance of the shrimp. The final body weight (FBW), weight gain (WG), and specific growth rate (SGR) of the shrimp in the PC group were similar to those in the BA2 group, and significantly higher than those in the other three groups. The survival rate (SR) was similar among all groups. In comparison to the PC group, the low fishmeal groups exhibited a significant decrease in the crude lipid content of the whole shrimp, as well as the Total cholesterol (T-CHOL), Low-density lipoprotein (LDL-C), and High-density lipoprotein (HDL-C) levels in the hemolymph. Regarding the sterol metabolism, the dietary supplementation of CDCA up-regulated the mRNA expression of intracellular cholesterol transporter 1-like (npc1), 7-dehydrocholesterol reductase (7dhcr), Delta (24) sterol reductase (Δ24), HMG-CoA reductase membrane form (hmgcr), and sterol carrier protein 2 (scp). In the lipid metabolism, the mRNA expression of sterol-regulatory element binding protein (srebp) was significantly down-regulated in the shrimp fed the BA1 diet and the expression of AMP-activated protein kinase (ampk) was significantly up-regulated in the shrimp fed the BA1 and BA3 diets compared to the PC group. The mRNA expression of triacylglycerol lipase (tgl) was significantly up-regulated in the shrimp fed the BA2 diet compared to the NC group. Compared with the shrimp fed the PC diets, the dietary supplementation of CDCA significantly down-regulated the protein expression of SREBP1. The lumen damage in the BA1 group was significantly less severe than those in the NC group. The addition of 0.06% CDCA to low fishmeal diets can improve the growth performance, lipid and cholesterol metabolism, and hepatopancreas health of L. vannamei.