Effects of Dietary Peppermint (Mentha piperita) Essential Oil on Growth Performance, Plasma Biochemistry, Digestive Enzyme Activity, and Oxidative Stress Responses in Juvenile Nile Tilapia (Oreochromis niloticus)

This study aimed to evaluate the supplementation of peppermint essential oil (Mentha piperita; PEO) in diets for juvenile Nile tilapia (Oreochromis niloticus). A feeding experiment with diets containing graded levels (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 g kg(-1)) of PEO was carried out with fish of 0.58 & PLUSMN; 0.08 g. The inclusion of graded levels of PEO in the diet improved the weight gain (0.52 g kg(-1)), feed intake (0.51 g kg(-1)), and feed conversion (0.51 g kg(-1)) of juvenile Nile tilapia in a quadratic pattern. Increasing levels of PEO also led to a linear decrease in body lipid content. The gut activity of the digestive enzymes amylase (0.54 g kg(-1)) and protease (0.39 g kg(-1)) increased quadratically, whereas lipase activity increased linearly. PEO increased the activity of the antioxidant enzymes catalase (CAT; 0.52 g kg(-1)) and superoxide dismutase (SOD; 0.58 g kg(-1)) while reducing the production of malonaldehyde (MDA; 0.40 g kg(-1)) and nitric oxide (NO; 0.63 g kg(-1)) in the liver. The results of this study provide evidence of the beneficial effects of PEO on the growth and health of Nile tilapia and recommend a dose of 0.6 g kg(-1) as the optimal level of supplementation.