Mechanism Study About The Effect Of Oregano Essential Oil And Cinnamon Essential Oil On Growth,Immunity And Disease Resistance Of Hybrid Grouper (Epinephelus Fuscoguttatus ♀ × E. Lanceolatus ♂)

Epinephelus fuscoguttatus ♀× E.lanceolatus ♂,as a typical marine carnivorous fish in China,has the characteristics of fast-growing,good meat quality and high market value.With the rapid development of its breeding industry,it is also faced with the problem of disease outbreak caused by many factors.As China enters the era of nonresistance,it is urgent to develop and apply highly effective functional plant additives.In this study,hybrid grouper(initial weight 19.10±0.12 g)were used as the object.Oregano essential oil(OO)(0 g/kg,0.1 g/kg,0.3 g/kg,0.6 g/kg,0.9 g/kg,1.2 g/kg)and cinnamon essential oil(CO)(0 g/kg,0.1 g/kg,0.3 g/kg,0.6 g/kg,0.9 g/kg,1.2 g/kg)were added to the feed in different proportions.After 8 weeks of feeding,the effect of different levels of OO and CO on the growth performance,physiological metabolism,antioxidant function and disease resistance of hybrid grouper were investigated based on 16 S high-throughput sequencing,transcriptomics and micro RNA omics technology.The main results were below:1.Effects of adding OO to diets on the growth,antioxidation,immunity,and intestinal health of hybrid grouper1)Adding 0.3 g/kg-1.20 g/kg OO in the experimental diet did not affect the growth performance of hybrid grouper;adding 0.3 g/kg OO in the experimental diet can improve serum biochemical indexes;0.3 g/kg-1.20 g/kg OO can improve the body’s antioxidant capacity and immunity;0.3 g/kg OO can accelerate liver fatty acid metabolism,fatty acid degradation,and promote the body to weaken inflammatory reactions,thereby achieving the function of protecting the body.Based on comprehensive evaluation of experimental indicators,the optimal amount of OO added to the diet for hybrid grouper was 0.3 g/kg;2)0.3 g/kg OO could improve the morphology of intestinal tissue and tight junction morphology of hybrid grouper;0.3 g/kg OEO can improve intestinal digestion,antioxidant,immune and other related physiological indicators;gut transcriptome sequencing confirmed that 0.3 g/kg OO could regulate the abundance of intestinal flora,the metabolism of intestinal lipids and amino acids in hybrid grouper.3)0.1 g/kg and 0.3 g/kg OO can significantly improve the survival rate of grouper infected with Vibrio harveyi;0.3 g/kg OO can improve serum and liver antioxidant and immune related indicators of grouper infected with Vibrio harveyi;liver mi RNA sequencing showed that 0.3 g/kg OO can regulate nutrient metabolism and immunerelated signaling pathways,and play a role in regulating the body health of hybrid grouper.2.Effects of adding CO to diets on the growth,antioxidation,immunity,and intestinal health of hybrid grouper1)Adding 0.9 g/kg CO in the experimental diet can improve the growth performance of hybrid grouper;adding of 0.3 g/kg and 0.9 g/kg CO in the experimental diet can improve serum biochemical indexes;0.3 g/kg-0.9 g/ kg CO were added to the feed can improve the body’s antioxidant capacity and immunity;0.9g/kg CO can accelerate liver lipid metabolism,promote the body to reduce inflammatory reactions,thereby achieving the function of protecting the body.Based on comprehensive evaluation of experimental indicators,the optimal amount of CO added to the diet for hybrid grouper was 0.9 g/kg.2)0.9 g/kg CO could improve the morphology of intestinal tissue and tight junction morphology of hybrid grouper;0.9 g/kg CO can improve intestinal digestion,antioxidant,immune and other related physiological indicators;Gut transcriptome sequencing confirmed that 0.9 g/kg CO could regulate the abundance of intestinal flora,intestinal short chain fat fatty acids(SCFAs)and lipid metabolism of hybrid grouper,and play its role in regulating body health.3)0.1 g/kg of CO can significantly improve the survival rate of grouper infected with Vibrio harveyi;Under Vibrio harveyi infection,0.9 g/kg CO can improve serum and liver antioxidant and immune related indicators of grouper infected with Vibrio harveyi;liver mi RNA sequencing showed that 0.9 g/kg of CO can regulate nutrient metabolism and immune-related signaling pathways,and play a role in regulating the body health of hybrid grouper.In summary,OO and CO play an important role in regulating the growth,immunity and disease resistance of hybrid grouper.This study preliminarily revealed the mechanism of OO and CO in promoting growth,elevating immunity and disease resistance,and enriched the nutritional information of the hybrid grouper.Under the experimental conditions,the appropriate amounts of OO and CO in diet were 0.3 g/kg and 0.9 g/kg,respectively.