Influence of laurel (Laurus nobilis) essential oil on gut function of Black Sea salmon (Salmo labrax) juveniles

Abstract

The present work investigated the efects of dietary incorporation of laurel (Laurus nobilis) essential oil on the zootechnical performance and digestive physiology of juvenile Black Sea salmon (Salmo labrax). In this trial, 15 fberglass tanks (39×39 cm square and 33 cm high) were used. Forty-fve fsh (3.52±0.01 g) were placed randomly per tank. Fish were fed for 90 days with the diet containing 50, 100, 200, or 400 mg kg−1 laurel (Laurus nobilis) essential oils, respectively. The work was performed in the recirculating aquaculture system (RAS) operating with freshwater. Fish were manually fed 3% level of live weight during the experiment period. Final weight (FW), weight gain (WG), feed conversion rate (FCR), and specifc growth rate (SGR) were not afected by laurel essential oil supplementation. Dietary laurel essential oil (50 mg kg−1) afected positively the surface area of fsh intestinal villus that required for digestion. Both villus height and villus width were afected positively in fsh fed with 50 mg laurel essential oil kg−1. While incorporation with 100 mg laurel essential oil kg−1 increased the total α-amylase enzyme, 50 mg laurel kg−1 increased lipase enzyme. Moreover, 50 mg laurel essential oil kg−1 increased lactic acid bacteria (LAB) count in fsh. Besides, 50 mg laurel essential oil kg−1 reduced the number of total coliform and E. coli.