The effect of dietary supplementation of medium-chain fatty acids products on gut and hepatopancreas health, and disease resistance in white shrimp (Litopenaeus vannamei)

This study was to investigate the effect of medium-chain fatty acids products Aromabiotic® Shrimp (ABS) on growth, gut and hepatopancreas health, gut microbiota and resistance to bacterial infection and adverse environment of white shrimp. Firstly, white shrimp were divided into five groups: control, ABS0.5, ABS1, ABS2, and ABS5 (with 0, 0.5, 1, 2 and 5 g/kg ABS in feed respectively). After 5-week feeding, there was no significant difference in weight gain, feed conversion ratio and survival among groups. However, ABS diets significantly improved the survival of the white shrimp after Vibrio parahaemolyticus challenge (ABS5, P < 0.05) and moldy diet feeding (ABS1 and ABS5, P < 0.05). On this basis, we selected the control, ABS1 and ABS5 groups for the second batch of feeding experiments. After 5-weeks feeding, the level of lipopolysaccharide binding protein (LBP) in intestinal tissue decreased significantly in ABS1 and ABS5 groups versus control (P < 0.05), while the intestinal expression of prophenoloxidase (proPO) and antimicrobial peptides (Crustin and Penaeidin-3a) significantly increased (P < 0.05). The expression of intestinal phenoloxidase (PO) in ABS5 group increased significantly (P < 0.01). The gut microbiota of ABS1 and ABS5 groups changed significantly, and the diversity of gut microbiota decreased. The histological structure of hepatopancreas in ABS1 and ABS5 groups was improved compared with control. The arrangement of hepatopancreas was more compact, and the structure of star-shaped lumen was more obvious. The level of glutamic pyruvic transaminase (ALT) in muscle tissue of ABS1 and ABS5 groups decreased significantly (P < 0.01). Furthermore, the expression of Lysozyme, Crustin and proPO in hepatopancreas was increased in both ABS groups versus control. Collectively, our results showed beneficial effects of dietary supplementation of ABS on gut and hepatopancreas health and disease resistance of white shrimp culture.