Effect of Different Dietary Selenium Sources on Growth Performance, Antioxidant Capacity, Gut Microbiota, and Molecular Responses in Pacific White Shrimp Litopenaeus vannamei

Abstract

This study investigated the effect of different dietary selenium (Se) sources on the growth performance, antioxidant capacity, gut microbiota, and molecular responses of the Pacific white shrimp Litopenaeus vannamei. Four Se sources (sodium selenite, L-selenomethionine, selenium yeast, or Se nanoparticles) were added to purified diets to 0.4 mg Se/kg diet for shrimp ( $1.60\pm 0.14\text{g}$ ). Each treatment was randomly assigned to 3 replicated tanks and 30 shrimp in each tank (500 L). After 8 weeks of breeding, L-selenomethionine and selenium yeast significantly increased weight gain compared with sodium selenite treatment, while sodium selenite significantly decreased the shrimp hepatosomatic index compared with the other groups. The L-selenomethionine significantly increased the superoxide dismutase and glutathione peroxidase activities in the hepatopancreas compared with the shrimp fed sodium selenite and decreased catalase activity and malondialdehyde content compared with other groups. The composition and β-diversity of gut microbiota were markedly changed in each group. The abundances of Rubrobacter and Rubritalea, Winogradskyella and Motilimonas, and Photobacterium in the gut microbiota were specially altered by L-selenomethionine, Se yeast, and Se nanoparticles, respectively. The sodium selenite group showed lower complexity of gut interspecies interactions. RNA-seq analysis showed that “arachidonic acid metabolism”-related genes were significantly enriched in the L-selenomethionine and Se yeast groups; “peroxisome” and “drug metabolism–other enzymes”-related genes were enriched in the Se nanoparticle group. Vibrio, Motilimonas, and Photobacterium were associated with amino acid and lipid metabolism. Pseudoalteromonas, Silicimonas, Roseovarius, and Halomonas inhibited the expression of glutathione peroxidase genes. These results suggested that organic Se, especially selenomethionine, is an effective feed supplement to promote growth and antioxidant capacity, maintain the health of gut microbiota, and promote the utilization of fatty acid and glutathione peroxidase genes in shrimp fed a 0.4 mg Se/kg diet.