Effects of dietary chenodeoxycholic acid supplementation in a low fishmeal diet on growth performance, lipid metabolism, autophagy and intestinal health of Pacific white shrimp, Litopenaeus vannamei

An 8-week feeding trial was conducted to evaluate the effects of chenodeoxycholic acid (CDCA) on growth performance, body composition, lipid metabolism, and intestinal health of juvenile white shrimp, Litopenaeus vannamei fed a low fishmeal diet. Four practical diets were formulated: HFM (25% fishmeal), LFM (15% fish-meal), LB1 (LFM + 0.04% CDCA), LB2 (LFM + 0.08% CDCA). Each diet was assigned to four tanks with forty shrimp (initial weight 0.33 ?+/- 0.03 g) per tank. The results indicated that the growth performance of shrimp were similar between the four groups; the crude lipid content of shrimp fed the LB2 diet was significantly lower than those fed the HFM diet (P < 0.05). The lipase activity content in hepatopancreatic were significantly higher in the two CDCA supplemented groups than that in LFM group; the contents of total cholesterol, low-density li-poprotein cholesterol, high-density lipoprotein cholesterol in hemolymph were significantly lower in LFM group, LB1 group and LB2 group than that in HFM group (P < 0.05). The shrimp fed LB1 diet was significantly decreased the intestinal expression levels of tube than those fed in HFM diet; the intestinal gene expression of imd and toll were significantly lower in LB2 group than those in HFM group (P < 0.05). The results of hepatopancreas gene expression suggest that shrimp fed the LFM diet showed significantly upregulated expression levels of sterol regulatory element-binding protein (srebp), acetyl-CoA carboxylase (acc), and carnitine palmitoyltransferase 1 (cpt-1) than those fed the HFM diet; shrimp fed the LB1 diet showed significantly upregulated expression levels of srebp, acc, and AMP-activated protein kinase (ampk) than those fed the HFM diet; shrimp fed the LB2 diet had higher expression levels of srebp, acc, and cpt-1 than those fed the HFM diet (P < 0.05). In the hepatopancreas, the shrimp fed the LFM diet shown significantly up-regulated the expression levels of beclin1 compared to those fed HFM diet; the expression levels of autophagy-related protein13 (atg3), autophagy-related protein 12 (atg12) of in shrimp fed the LB1 diet were significantly higher than those fed the HFM diet; and the expression levels of autophagy-related protein13 (atg13), beclin1, atg3, atg12, autophagy-related protein 9 (atg9) of shrimp fed LB2 diet were significantly higher than those fed the HFM diet (P < 0.05). The atg3 in intestine of shrimp fed the LB2 diet were significantly higher than those fed the HFM diet (P < 0.05). Intestinal mucous fold were damaged, hepatic tubules were disorganized and B cells appeared to be swollen in LFM group. The fold height and width of shrimp fed the diets supplemented with CDCA increased significantly than those fed the LFM diet (P < 0.05), the hepatic tubules were neatly arranged, and R cells increased. In conclusion, supplementary CDCA in a low fishmeal diet promoted lipid metabolism, enhanced autophagy of shrimp, also improved the health of the in-testine and hepatopancreas.