Antioxidant status and performance of Macrobrachium rosenbergii juveniles fed diets containing non-nutritive Aloysia triphylla essential oil

Incorporating essential oils as dietary supplements in aquaculture is increasing in popularity. In prawn farming, their use is associated with reduced disease outbreaks, enhanced immunity, and improved animal growth and welfare. Herein, we explored the use of lemon beebrush essential oil ( Aloysia triphylla ; EOAT) in the diet of juvenile giant freshwater prawns ( Macrobrachium rosenbergii ) and its potential impact on growth performance and oxidative status of the hepatopancreas. Four hundred juvenile M. rosenbergii (0.40 ± 0.19 g, similar weights between sexes) were fed diets containing concentrations of EOAT at 0.0% (control), 0.1%, 0.2%, or 0.3% for 50 days. Each experimental group had five replicates, with 20 prawns per experimental unit. Prawn survival remained above 84% for all experimental groups. Prawn weight gain, specific growth rate, feed conversion ratio, and body condition were similar among all experimental groups. Dietary EOAT increased activities of the enzymatic antioxidants, catalase and superoxide dismutase, and varied glutathione S transferase activity in the hepatopancreas of prawns when compared to those fed the control diet. Dietary EOAT did not affect malondialdehyde (lipid peroxidation) levels. While EOAT had no impact on survival and growth of M. rosenbergii , it may modulate the detoxification capacity of the hepatopancreas (i.e., metabolic resistance). Future work should prospect EOAT as part of a nutraceutical blend, especially when combined with known growth enhancers and immune stimulants. Based on our results, dietary inclusion of 0.2% EOAT is the most suitable for juvenile M. rosenbergii farming.