Effects of dietary costmary (Tanacetum balsamita) essential oil on growth performance, digestive enzymes' activity, immune responses and subjected to ambient ammonia of common carp Cyprinus carpio

The present study aimed at investigating the effects of dietary costmary, Tanacetum balsamita, essential oil (CEO) on growth performance, digestive enzymes' activity, and physiological responses to ammonia exposure in common carp, Cyprinus carpio. Common carp (∼17 g) were randomly distributed in 15 tanks as five treatments receiving diets containing 0 (CTL), 100 (100E), 200 (200E), 300 (300E), and 400 (400E) mg/kg CEO for eight weeks and then exposed to 0.5 mg/l unionized ammonia nitrogen for 3 h. The results showed that dietary CEO significantly increased growth performance and feed efficiency and the best values were observed in 100E and 200E treatments. Intestinal amylase, lipase, and protease activities significantly increased in 100E, 200E, and 300E treatments, compared to CTL, and the highest amylase activity was related to 100E, and highest lipase and protease was related 100E and 200E treatments. Dietary CEO significantly decreased serum cortisol, glucose, catalase, malondialdehyde, alanine aminotransferase, aspartate aminotransferase, triglyceride, cholesterol, and low-density lipoprotein, but increased serum superoxide dismutase, glutathione peroxidase, lysozyme, complement, total immunoglobulin, high density lipoprotein, total protein, and albumin before and/or after ammonia stress, depending on CEO concentrations. Based on the present results, dietary CEO supplementation can improve digestive enzymes and growth performance of common carp. Moreover, CEO exhibits anti-stress, antioxidant, hepatoprotective, and immunostimulant effects in common carp under ammonia toxicity. Based on the results, 100–200 mg/kg CEO is recommended for common carp feed supplementation.