Cholesterol supplementation improved growth performance, cholesterol metabolism, and intestinal health of Pacific white shrimp (Litopenaeus vannamei) fed a low fishmeal diet

An 8-weeks feeding trial was conducted to evaluate the effects of dietary cholesterol supplementation on growth performance, hemolymph biochemical parameters, cholesterol metabolism, intestinal health, and disease resistance of Pacific white shrimp (Litopenaeus vannamei) fed a low fishmeal diet. Four experimental diets including HFM (25% fishmeal), LFM (15% fishmeal+10% soy protein concentrate), LC1 (LFM+0.6 g kg⁻¹ cholesterol), and LC2 (LFM+1.2 g kg⁻¹ cholesterol) were formulated, each diet was fed to quadruplicate tanks with 40 shrimp (0.33 ± 0.03 g) per tank for 56 days. The results shown that cholesterol supplementation in the diet did not affect the growth performance of Litopenaeus vannamei (P > 0.05), but the crude lipid content significantly reduced in the LC2 group than that in HFM group (P < 0.05). In the hemolymph biochemical indices, the content of total cholesterol in LFM and LC1 groups were significantly lower than that in HFM group; the HDL-C content was significantly lower in the shrimp fed low fishmeal based-diets (LFM, LC1, and LC2) than those fed in HFM diet; the TG content of two cholesterol supplemented groups were significantly lower than that of HFM group; the MDA content was significantly higher in LFM group than that in HFM group (P < 0.05). In hepatopancreas lipid metabolism, the shrimp fed LFM diet has higher expression in srebp, fas, and acc than those fed the HFM diet, and two cholesterol groups significant decreased the acc relative expression compare with LFM group; compare with HFM group, the LFM group showed significantly up-regulated hmg-CoA, npc1 relative expression, and LC1 group significantly up-regulated scp relative expression, then LC2 group significantly up-regulated scp, npc2 relative expression of hepatopancreas in cholesterol metabolism; LFM, LC1 group significantly up-regulated beclin1, atg12 relative expression and LC2 group up-regulated beclin1 relative expression than those in HFM group of hepatopancreas in cell autophagy (P < 0.05). LC1 group up-regulated imd, relish, toll, myd88, pelle, tube, and dorsal relative expression and LC2 group up-regulated ikkβ, myd88, tube, and dorsal relative expression in intestinal immunity than those in HFM group (P < 0.05). Cholesterol supplementation increased the height of the intestinal folds of shrimp fed the low fishmeal based-diets (P < 0.05), as well as improved the integrity of the mitochondria and the endoplasmic reticulum. Dietary cholesterol supplementation decreased the abundance of harmful bacteria phylum (Chlamydiae) and increased the abundance of beneficial bacteria genus (Pseudoalteromona, Rhodopirellula, and Ruegeria) compared with LFM group (P < 0.05). Shrimp fed the LC1 diet showed higher resistance to V. parahaemolyticus challenge than those fed the LFM diet (P < 0.05). In conclusion, cholesterol supplementation in a low fishmeal diet significantly enhanced the lipolytic capacity of shrimp, promoted the cellular autophagy, improved the intestinal health, and enhanced disease resistance of Litopenaeus vannamei.