Taurochenodeoxycholic Acid Improves Growth, Physiology, Intestinal Microbiota, and Muscle Development in Red Swamp Crayfish (Procambarus clarkii)

Taurochenodeoxycholic acid (TCDCA), one of the bile acids, is thought to be involved in the regulation of muscle nutrient metabolism and gut microbial homeostasis. However, the effect of dietary addition of TCDCA on Procambarus clarkii is unclear. Therefore, in this study, an 8-week feeding experiment was conducted to explore the potential regulatory mechanisms of TCDCA on P. clarkii growth, physiology, muscle quality and gut microbes. The results indicated that dietary addition of TCDCA not only improved growth performance (final weight; weight gain; and specific growth rate) but also increased muscle elasticity and protein content. In addition, dietary TCDCA promotes muscle growth and development by increasing myofiber length, which is consistent with the activation of the expression of genes related to protein utilization (TOR and AKT) and muscle proliferation and differentiation (MyHC, MLC1, MEF2A, MEF2B). Importantly, 16s rRNA sequencing demonstrated that dietary TCDCA had no significant effect on gut microbial composition (alpha diversity) but significantly increased microbial abundance at the genus level. Functional prediction analysis of differential microbes revealed that dietary TCDCA may promote metabolism by altering gut microbes, thereby promoting muscle quality. In conclusion, our study demonstrates that the dietary addition of TCDCA promotes P. clarkii growth and muscle quality and protein deposition by altering gut microbes.