Dietary condensed tannins improved growth performance and antioxidant function but impaired intestinal morphology of Litopenaeus vannamei

Although effects of dietary condensed tannins (CT) on growth and health of fish have been evaluated, limited information is available on shrimp. This study investigated the effects of CT on growth, nutrient digestibility, antioxidant response and intestinal histomorphology of Litopenaeus vannamei. A 56-day feeding trial was conducted by randomly distributing 600 shrimp into 15 tanks with 40 shrimp per tank and fed five diets containing 0 (G0), 0.5 (G0.5), 1 (G1), 2 (G2) and 4 (G4) g/kg of grape seed CT respectively. Shrimp were fed to apparent satiation during the entire feeding trial and feces were collected daily for the last 14 days to determine nutrient digestibilities. Hepatopancreas and intestine samples were collected to analyze antioxidant-related genes expression and histomorphology. Results indicated that dietary CT linearly increased final body weight, weight gain rate and specific growth rate (0.05 < P < 0.10) but linearly decreased feed coefficient of shrimp (0.05 < P 0.10). All shrimp had similar apparent digestibility coefficient of dry matter, crude protein, crude lipid and ash (P 0.05). As compared with G0, dietary CT increased superoxide dismutase (G0.5, G1 and G2), glutathion peroxidase (G1 and G2) and nuclear factor erythroid 2-related factor 2 (G0.5, G1, G2 and G4) mRNA levels (P < 0.05). Intestinal villus in G1, G2 and G4 were shown to have different degrees of deformation with villus length was higher and villus width was lower in G1 and G2 than in other groups (P < 0.01). In summary, dietary inclusion of 0.5-4 g/kg grape seed CT increased growth but did not alter nutrient digestibilities of Litopenaeus vannamei. Supplementation of CT in shrimp diets up-regulated the antioxidant-related genes expression but induced intestinal histomorphology lesions.

Automated summary

This study found that inclusion of 0.5-4 g/kg grape seed CT in the diet can increase the growth of Litopenaeus vannamei, but does not affect nutrient digestibilities. Additionally, supplementation of CT in shrimp diets up-regulated the expression of antioxidant-related genes while inducing intestinal histomorphology lesions.