Effect of dietary nutmeg (Myristica fragrans) on growth performance, antioxidant status, immune response, and gene expression of common carp (Cyprinus carpio)

The aim of this study was to assess the effects of dietary nutmeg (Myristica fragrans (MF)) on growth, innate immunity parameters of serum and mucus, antioxidant defence, and expression of immune genes in common carp (Cyprinus carpio). Three hundred fish (3.79 ± 0.02 g) in four groups were distributed in twelve glass aquariums with a capacity of 150-L. The groups were T1 or control (0% MF), T2 (0.5% MF), T3 (1% MF), and T4 (2% MF), and the fish were sampled after 42 days. According to the results, diet supplementation showed significantly higher weight gain (WG) and lower food conversion ratio (FCR). Final weight (FW) increased in groups fed 1% and 2% MF and specific growth rate (SGR) improved in those provided 1% MF (P < 0.05). Alternative complement activity (ACH50) and the total immunoglobulin (total Ig) level were found to be significantly higher in T4 and T3 groups, respectively than in the T1 (P < 0.05). However, lysozyme (LYZ) and total protein (TP) in all treatment groups showed no significant variation compared with the T1. Similarly, feeding fish with supplemented diets did not affect the antioxidant status and mucus immune parameters. Additionally, fish fed 1% MF showed a significantly higher intestinal catalase (CAT) and superoxide dismutase (SOD) gene expression (P < 0.05). However, LYZ expression significantly decreased in the fish fed MF (P < 0.05). The results of the present study revealed the addition of MF to the diet affects the expression of both antioxidant and immune genes in common carp.