Dietary Bile Acids Supplementation on Growth Performance and Metabolism in Pacific White Shrimp (Litopenaeus...

Optimizing bile acids (BAs) inclusion in commercial diets and understanding its molecular mechanisms in Pacific white shrimp (Litopenaeus vannamei) are crucial for improving growth performance. The present study investigated the effect of dietary BAs on shrimp growth and metabolic mechanisms using multiomics approaches. A total of 1800 shrimp (0.16 ± 0.01 g) were fed six diets with BAs levels: 0 mg kg^-1 (control, BA0), 50 mg kg^-1 (BA1), 100 mg kg^-1 (BA2), 150 mg kg^-1 (BA3), 200 mg kg^-1 (BA4), and 250 mg kg^-1 (BA5). After 56 days, the growth performance of BA4 and BA5 groups was significantly higher than the BA0, BA1, and BA2 groups. Regression analysis indicated an optimal dietary BAs level of 216-218 mg kg^-1. Biochemical analysis showed that the BA4 group significantly reduced crude lipid content, triglycerides, and nonesterified fatty acids, while increasing digestive enzyme activities. RNA-seq revealed reduced expression of lipid synthesis genes (srebp1, fasn, scd, etc.), while enhancing the expression of genes related to lipid catabolism (acox1, angpt4, dip13a, and gba) and digestive enzymes (prss1 and prss2). Metabolomic analysis showed taurine-conjugated BAs as predominant, with taurine content decreasing likely due to its conjugation with BAs and loss in feces. These results suggest that the optimal BAs level of 216-218 mg kg^-1 improved shrimp growth and lipid metabolism by enhancing nutrient digestion, promoting lipolysis, and inhibiting lipid synthesis, without altering the BAs pool balance. This study first revealed taurine's critical role in Pacific white shrimp BAs metabolism.