Effects of Essential Oil Derived from the Bitter Orange (Citrus aurantium) on Growth Performance, Histology and Gene Expression Levels in Common Carp Juveniles (Cyprinus carpio)

SIMPLE SUMMARY: The aim of this analysis was to reveal the effects of Citrus aurantium essential oil on growth performance, histopathological effect on digestive system organs, expression levels of some growth-related genes in the muscle tissue and some immune-related genes in the head kidney of common carp Cyprinus carpio. To determine the effect of essential oil on carp, experimental diets containing different concentrations of essential oil were prepared, and the fish were fed these diets for 60 days. At the end of the feeding experiment, it was observed that low-dose essential oil supplementation increased immune related gene expression levels and growth-related gene expression levels in head kidney and muscle tissue, respectively. Pathological findings were observed in the liver and intestines of fish fed with high doses of essential oil supplemented diets. ABSTRACT: The aim of this study was to detect effects of bitter orange (Citrus aurantium) essential oil, commonly called neroli oil (NO) (0, 0.25, 0.50, 1, and 1.5% referred to as NO(0) NO(0.25), NO(0. 05), NO(1) and NO(1.5), respectively) on growth performance output and expression levels of some growth-related genes in the muscle tissue and some immune-related genes in the head kidney and pathological differences in digestive system organs of common carp Cyprinus carpio. The NO(0.25) group had a large improvement in growth efficiency at the end of the 60-day feeding cycle. Real-time PCR (Bio RAD, USA) system was used to detect variations in gene expression levels. Furthermore, NO supplementation of up to 0.25% in muscle tissue controlled the release of growth hormone (GH) and insulin-like growth factor I (IGF-I). Furthermore, in the NO(0.25) treatment category, immune response gene levels TNF-α, IL-8 and IL-1ß increased in head kidney tissue. In the histological examination of the liver and intestine, there were significant differences between fish fed with N(1) and N(1.5) diets. This study confirms that dietary supplementation of NO up to 0.25% can improve common carp growth efficiency and increase the expression of genes (GH and IGF-I) related to muscle growth, TNF-α, IL-8 and IL-1ß genes related to immune status, and liver and intestine histological status of common carp.