| Grouper cultivation in the world is mainly concentrated in east Asia and southeast Asia coastal areas.China’s grouper culture is mainly concentrated in the coastal provinces of Guangdong,Fujian,Hainan,Taiwan and other provinces.In recent years,with the rise of a new model of grouper culture,in Guangdong,Hainan and other northern provinces.The grouper(Epinephelus fuscoguttatus♀×E.polyphekadion♂)is a hybrid progeny cultivated after fertilization of eggs of brown spot grouper and sperm of clear water grouper.It is a new breed large family of grouper in China in recent years.It inherits the advantages of parents,has the characteristics of strong resistance to stress and fast growth,and its meat quality is fresh and tender.Rich in nutrition,in Hainan,Guangdong area by many farmers love,is a market prospect of new varieties of grouper.However,the relationship between the living environment,the level of basic nutritional needs and the molecular mechanism of the rapid growth of Chinese fir are not reported.in order to reveal the optimal growth environment needed for the growth of E.fuscoguttatus,the protein fat nutrition level to meet its growth needs,and the molecular regulation mechanism of its growth difference,this study aimed at the effect of salinity on the growth of E.fuscoguttatus,the relationship between feed protein fat level and growth of E.fuscoguttatus,and the sequencing analysis of liver and muscle tissue of E.fuscoguttatus and its parent(brown spot grouper).The results was followed:1.With the increase of feed fat level,the weight gain rate of fir spot increased first and then decreased,among which L4 group had the largest weight gain rate,which was significantly higher than L1、L5 group(P<0.05);the increasing weight(WGD),specific growth rate(SGR),fertilizer fullness(CF)and protein efficiency(PER)of young fir spot showed the trend of first increasing and then decreasing.With the increase of feed fat level,the feed coefficient(FCR)of the hybrid grouper decreased first and then increased,among which L4 group had the lowest feed coefficient,which was significantly lower than that of L1、L5 group(P<0.05).As the feed fat level increased,the VSI、HIS of E.fuscoguttatus showed a tendency of increasing gradually.With the increase of feed fat level,the crude protein content of the whole fish was gradually decreased,and the crude protein content of L1 group was significantly higher than that of other experimental groups(P<0.05);the protein level of the whole fish was gradually decreased;the water content of the whole fish in each group was not affected by the feed fat level(P>0.05).With the increase of feed fat level,the crude protein content of hybrid groupers muscle showed that L1 group was significantly higher than that of other test groups(P<0.05);with the increase of fat level,the crude fat content of Hybrid groupers muscle gradually increased,L5 group was significantly higher than that of other experimental groups(P<0.05);with the increase of fat level,the muscle ash content gradually increased.According to the above analysis,the lipid levels of the fish of the hybrid grouper was9.91%～10.28%.2.By adjusting the level of dietary fat,the growth performance of E.polyphekadion was improved,and the growth characteristics of E.polyphekadion,the enzyme activities of liver and intestine were increased,metabolic metabonomics was used to analyze the regulation of dietary protein level on the growth mechanism of E.polyphekadion.Feeding 10% fat in the diet can promote the growth of juvenile Chinese Tiger Grouper.Metabonomics analysis was used to reveal the mechanism of the suitable fat diet for the young fish,mainly by regulating the metabolism of Pyrimidine,Tryptophan,octadecenoic acid,amino sugar and Nucleotide sugars metabolism,low Fat levels create a nutritional imbalance,and feeding low fat levels limits the growth of the young.3.With the increase of feed protein level,the weight gain rate of young fish increased first and then decreased.At 50% protein level,the weight gain rate of young fish was significantly higher than that of other experimental groups(P<0.01).As the feed protein level gradually increased,there was no significant effect on the crude protein level of the whole fish and the muscle crude protein content gradually increased;as the feed protein level increased,the whole fish and muscle crude fat content of the young fish gradually decreased;and there was no significant effect on the whole fish and muscle moisture(P>0.05).With the increase of feed protein,the enzyme activities of superoxide dismutase(SOD),catalase(CAT)and lysozyme(LZM)in the liver of juvenile E.fuscoguttatus increased first and then decreased.With the increase of feed protein level,the DNA content did not change,but the RNA content increased first and then decreased gradually.According to the above analysis,the suitable protein level of hybrid grouper was 45%～55%,and the optimum protein level was 49.44%.4.To study the effects of dietary protein levels on the growth characteristics,liver enzyme activity and enteric enzyme activity of FPE respectively,and compares the differences in the mechanism of protein level causing the growth of FPE by metabonomics and gut microbiota analysis.The results show that 50% dietary protein levels could significantly enhance the FPG juveniles in growth,environmental adaptability and digestibility.Meanwhile,the metabonomics results of intestinal tissue suggested that 640 metabolites were identified and 143 metabolites differed significantly between two group.Bioinformatics analysis showed that the 143 metabolites were predominantly related to pyrimidine metabolism,insulin resistance,beta-Alanine metabolism,arachidonic acid metabolism,and amino sugar and nucleotide sugar metabolism. |
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