Dietary sodium benzoate improves growth, morphology, antioxidant capacity and resistance against Aeromonas hydrophila of Pacific white shrimp (Litopenaeus vannamei)

Abstract

Acidifier has become one of the most important substitutes for antibiotics, and its beneficial effects on growth performance and digestive ability have been evidenced. Sodium benzoate is a commonly used acidifier. A 56-day feeding test was carried out to elucidate the effects of dietary sodium benzoate on growth performance, morphology, antioxidant activity and intestinal microflora of juvenile Litopenaeus vannamei with an average initial body weight of 0.55 ± 0.01 g. Six experimental diets were prepared by adding 0, 750, 1000, 1250, 1500 and 1750 mg/kg sodium benzoate to the control diet. The results showed that: The final body weight (FBW) and weight gain (WG) of juvenile shrimp were significantly improved by diet supplemented with 1750 mg/kg sodium benzoate. Dietary 1750 mg/kg sodium benzoate significantly increased the trypsin activity. The activities of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST) in the intestine and hepatopancreas of the 1750 mg/kg sodium benzoate group were markedly higher than those of the control group. Furthermore, the expression levels of trypsin (TRY), amylase (AMS), lysozyme (LZM), interleukin-8 (IL8) and interleukin-10 (IL10) genes in the intestine significantly increased when the content of sodium benzoate in the diet was greater than or equal to 1000 mg/kg. The addition of 1500 and 1750 mg/kg sodium benzoate to the feed improved the intestinal and hepatopancreatic tissue structures of juvenile shrimp and enriched the diversity of intestinal microbiota. Sodium benzoate residues were not detected in each sodium benzoate supplemented group. At the end of the Aeromonas hydrophila challenge test, juvenile shrimp in the 1500 and 1750 mg/kg group exhibited significantly higher cumulative survival rates than that in the control group. Conclusively, dietary 1750 mg/kg sodium benzoate could improve the growth performance, antioxidant capacity, morphology, intestinal microflora and disease resistance of juvenile shrimp.