Effect of supersaturated dissolved oxygen on growth- survival- and immune-related gene expression of Pacific white shrimp (Litopenaeus vannamei)

Abstract

Background and Aim: Oxygen concentration is an essential water quality parameter for aquaculture systems. Recently supersaturated dissolved oxygen (DO) has been widely used in aquaculture systems to prevent oxygen depletion; however the long-term effects of supersaturated DO exposure on aquatic animals have not been studied. In this study we examined the effects of supersaturated DO on the growth survival and gene expression of Pacific white shrimp (Litopenaeus vannamei). Materials and Methods: Specific pathogen-free shrimp with a body weight of 8.22 ? 0.03 g were randomly assigned to two groups with four replicates at a density of 15 shrimps per tank. Shrimp were cultivated in recirculating tanks containing 50 L of 15 ppt seawater in each replicate. Oxygen was supplied at 5 mg/L to the control tanks using an air microbubble generator and at 15 mg/L to the treatment tanks using a pure oxygen microbubble generator. Shrimp were fed commercial feed pellets containing 39% protein at 4% of their body weight per day for 30 days. Average daily growth (ADG) and feed conversion ratio (FCR) were determined on days 15 and 30. Shrimp molting was measured every day. Individual hemolymph samples were obtained and analyzed for total hemocyte count differential hemocyte count and expression of growth- and immune-related genes at the end of the experiment. Results: Long-term exposure to supersaturated DO significantly affected shrimp growth. After 30 days of supersaturated DO treatment the final weight and ADG were 14.73 ? 0.16 g and 0.22 ? 0.04 respectively. Shrimp treated with normal aeration showed significantly lower weight (12.13 ? 0.13 g) and ADG (0.13 ? 0.00) compared with the control group. FCR was 1.55 ? 0.04 in the treatment group and 2.51 ? 0.09 in the control group. Notably the shrimp molting count was 1.55- fold higher in the supersaturated DO treatment than in the supersaturated DO treatment. The expression of growth-related genes such as alpha-amylase cathepsin L and chitotriosidase was 1.40- 1.48- and 1.35-fold higher respectively after supersaturated DO treatment. Moreover the treatment increased the expression of anti-lipopolysaccharide factor crustin penaeidin3 and heat shock protein 70 genes by 1.23- 2.07- 4.20- and 679.04-fold respectively compared to the controls. Conclusion: Supersaturated DO increased growth and ADG production and decreased FCR. Furthermore enhanced immune-related gene expression by supersaturated DO may improve shrimp health and reduce disease risk during cultivation. ? 2024 Veterinary World. All rights reserved.