Bile acid supplementation in a high-fat diet improved growth performance, lipid deposition, ferroptosis, and intestinal health in Pacific white shrimp (Litopenaeus vannamei)

Abstract

Emerging evidence highlights bile acid (BA) as a key regulator of lipid homeostasis in shrimp, enhancing growth performance in aquaculture. This study aimed to investigate the effects of dietary BA supplementation in high-fat diets on growth performance, lipid deposition, intestinal health, and ferroptosis in Litopenaeus vannamei. An 8-week feeding trial was conducted using, eight different diets formulated with two lipid levels (7% and 11%) and four BA supplementation levels (0, 200, 400, and 800 mg/kg). The diets were named as LFD, LF200, LF400, LF800, HFD, HF200, HF400, and HF800, respectively. A total of 1280 shrimp (0.52 ± 0.01 g) were divided into eight groups with four replicates, stocking 40 shrimp in each replicate tank. Shrimp fed high-fat diets exhibited comparable final body weight (FBW) and weight gain rate (WGR) compared to those fed low-fat diets. However, shrimp receiving 400 mg/kg BA-supplemented diets demonstrated a significant increase in FBW and WGR compared to the high-fat control group (P < 0.05). Compared to low-fat diets, high-fat diets significantly elevated whole-body lipid content in shrimp and increased hepatopancreatic levels of total cholesterol (T-CHO), triglycerides (TG), and nonesterified fatty acids (NEFA) (P < 0.05). Additionally, feeding high-fat diets upregulated genes associated with lipid metabolism, such as ampk, fabp, and srebp, in both hepatopancreas and intestines (P < 0.05). However, the addition of BA was effective in reducing the above indicators (P < 0.05). Transmission electron microscopy revealed that high-fat diets led to mitochondrial abnormalities in the intestine, including the disappearance of mitochondrial cristae. Immunostaining of the intestine confirmed that high-fat diet markedly reduce the protein expression of GPX4, and the addition of BA significantly up-regulated ferroptosis-related genes—gpx4 and fettrin, enhanced GPX4 protein expression, downregulated the gene expression of acsl4, and reduced the malondialdehyde (MDA) content (P < 0.05). Moreover, the addition of BA to high-fat diets restructured the intestinal microbiota, improved intestinal histological structure, and increased the diversity indices of the intestinal microbiota. It also elevated the levels of Tenacibaculum, Motilimonas, Ruegeria, and significantly reduced the relative abundance of Kurthia (P < 0.05). These findings indicated that dietary BA supplementation may enhance growth performance, lipid metabolism, ferroptosis, and intestinal health of shrimp while mitigating the negative effects of a high-fat diet.