The ameliorative role of ascorbic acid against blood disorder, immunosuppression, and oxidative damage of oxytetracycline in rainbow trout (Oncorhynchus mykiss)

Saeed Moradi,Pooria Gholamzadeh,Kamran Rezaei Tavabe,Sina Javanmardi

doi:10.1007/s10695-022-01045-9

Abstract

This experiment was aimed to determine the possible beneficial effects of dietary ascorbic acid (AA) on hematological indices, immune responses, and antioxidative capacity of Oncorhynchus mykiss treated with antibiotic oxytetracycline (OTC). A total of 150 fish were divided evenly among five experimental groups (30 fish of each, in 3 replicates) receiving diets containing OTC (0 and 100mg per kg fish weight) and AA (100, 200, 400, and 800mg per kg fish diet) for 28days. Treatments include group A or control (100mg AA without OTC), group B (100mg AA with OTC), group C (200mg AA with OTC), group D (400mg AA with OTC), and group E (800mg AA with OTC). The results obtained showed that the hematological indices (red blood cells, white blood cells, hematocrit, hemoglobin, and neutrophils), immunological parameters (plasma lysozyme, plasma complement, and skin mucus alkaline phosphatase activities), and antioxidant enzymes activities (superoxide dismutase and catalase) were significantly decreased by OTC in O. mykiss fed control diet (P < 0.05). The results also revealed that OTC significantly increased the activity of biochemical enzymes (aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) in the plasma of O. mykiss fed control diet (P < 0.05). However, in comparison to the control diet, feeding fish with higher amounts of AA (400 and 800mg/kg diet) significantly restored the hematological, immunological, and antioxidative responses in OTC-treated groups (p < 0.05). These findings show that the dietary supplementation of AA at 400 or 800mg/kg diet is beneficial in relieving O. mykiss from OTC-induced oxidative stress and immunosuppression.

Highlights

During the previous decade, the outbreak of infectious diseases has emerged as a major limiting factor for aquaculture expansion which causes massive mortality and economic losses (Shalini et al 2019)
Vitamin C or L-ascorbic acid (AA) is a water-soluble micronutrient needed for multiple physiological process of aquatic animals (Shahkar et al 2015)
Considering the beneficial effects of AA, the current study evaluated the possible role of dietary AA in the reduction of OTC-induced stress in O. mykiss

Summary

Introduction

The outbreak of infectious diseases has emerged as a major limiting factor for aquaculture expansion which causes massive mortality and economic losses (Shalini et al 2019). Tetracyclines are a common class of antibiotics which are widely used in aquaculture. Oxytetracycline (OTC) is a well-known tetracycline antibiotic that is produced from Streptomyces rimosus fungi (Rodrigues et al 2017a; FAO 1990). OTC is commonly used as an effective treatment against bacterial pathogens of fishes, such as Aeromonas salmonicida, Aeromonas hydrophila, Lactococcus garvieae, Vibrio anguillarum, and Pseudomonas sp. More utilization of OTC than other antibiotics is due to its low-cost, legal availability, high efficiency and non-specific selectivity in the treatment of bacterial infection (Pês et al 2018; Lee et al 2020; Rodrigues et al 2017a). OTC can be applied via injection, immersion and oral administration, but is commonly administered through diet in the amount of approximately 75 mg per kg of fish biomass (Yonar 2012)

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Conclusion