Clostridium autoethanogenum protein substitution and bile acids addition altered intestinal health and transcriptome profiles of hepatopancreas in Litopenaeus vannamei

Dietary Clostridium autoethanogenum protein (CAP) has the potential to replace fishmeal (FM), but excessive CAP substitutions will affect gut health. Bile acids (BAs) have multiple benefits, but little information is available on the effects of BAs on Pacific white shrimp (Litopenaeus vannamei) fed a CAP diet (CAP replacing FM). An 8-week feeding trial were used to investigate the impacts of CAP substitution and BAs addition on structural changes of intestine, apoptosis, inflammatory cytokine and NF??B pathway of intestine, and transcriptomic profiles of hepatopancreas in Pacific white shrimp. Compared to PC (control) treatment, the NC (CAP50, CAP replacing 50% FM) treatment significantly decreased the fold height (FH) and villus length (VL) of midgut, and impaired the mitochondrial cristae. Compared to NC group, the FH was increased in BA1 (CAP50 with 0.03% BAs) and BA2 (CAP50 with 0.06% BAs) groups, the muscle layer thickness (MT) was decreased in BA2 and BA3 (CAP50 with 0.09% BAs) groups, the VL was increased in BA1 group, and the mitochondrial cristae was normal and welldefined in BA1 and BA2 groups (all p < 0.05). The NC increased the genes expression of apoptosis and NF??B signalling pathway, while the BA2 decreased the genes expression of apoptosis, inflammatory cytokine and NF??B signalling pathway. In transcriptomics analysis, a total of 171 differential expression genes (DEGs) were identified in NC group and 50 DEGs in BA2 group. There was 13 DEGs was observed both in NC and BA2 groups. The 5 KEGG pathways were statistically enriched in all treatments, including ???Carbon metabolism???, ???One carbon pool by folate???, ???Glycine, serine and threonine metabolism???, ???Amino sugar and nucleotide sugar metabolism???, and ???PPAR signaling pathway???. In conclusion, CAP50 substitution impaired the intestinal health and 0.06% BAs addition improved it, both treatments altered the transcriptomics profiles of hepatopancreas in Pacific white shrimp.