Comparisons The Intestinal Microbiota Characterizations, Enzyme Activities, And Muscle Amino Acid Compositions Of Loach In Two Cultivation Modes(Paddy Fields And Ponds)in Sichuan

Pond culturing is an important intensive breeding mode,but it has a negative impact on the environment due to the highly density.As a classical ecological cultivation mode,farming fish in paddy fields has a lowly density and good water quality.However,the study of specific mechanisms for its advantages was seldom reported.In present study,we studied the difference of the intestinal morphological and histological structure,microorganism,enzymatic activities,and amino acid composition of Paramisgurnuts dabryanus(chinese loach),which cultivated in paddy fields and ponds.It provides the basis to reveal the mechanism of different cultivation modes.The results are as follows:1 The observation of intestinal morphological and histologicalThe value of the intestines length/body length,intestines length/overall length and carcass weight/weight of loach were higher in paddy fields.And the index of carcass weight/weight of loach was significant higher in paddy fields than in ponds(P<0.05).In the same cultivation mode,the indicators of perimeter,folds height and radical,absorption area and mucous cell number in foregut were highly significant higher than these which were in midgut and hindgut(P<0.01).The number of folds radical in paddy cultivation mode was significantly higher than that of pond model(P<0.01).And there was no significant difference in the intestinal absorption area.2 Intestinal microbiota analysisSeasonal differences were found in the intestinal microflora of different cultivation modes.In the paddy cultivation mode,the bacterial diversity was higher for the epithelial intestinal mucosa,content and water samples in the autumn than in the summer,and the Plesiomonas sp.was only detected in autumn.In the pond cultivation mode,the bacterial diversity was lower for the epithelial intestinal mucosa and content samples in the autumn than in the summer,and the Actinobacterium was only detected in summer.Moreover,the Stenotrophomonas sp.only was detected in paddy cultivation mode,and the Shewanella sp.only was detected in pond cultivation mode.12 dominant bacteria were identified in the two models,and the classification was the same at the gate level,Proteobacteria(75%),Firmicutes(8.33%)and Actinobacteria(8.33%).In the summer,the abundance of Firmicutes,Lactobacillus spp.and Streptococcus spp.in mucosa in paddy cultivation mode were higher than that of in pond cultivation mode(P<0.05).In the autumn,the abundance of Bifidobacterium and Enterobacteriaceae in mucosa in paddy cultivation mode were higher than that of in pond cultivation mode(P<0.05).3 Intestinal enzymatic activities analysisThe activities of lipase in liver,foregut,midgut and hindgut in paddy cultivation mode were higher than that of in pond cultivation mode(P<0.05);and the activities of amylase and trypsin which were only in the midgut and hindgut in paddy cultivation mode were higher than that of in pond cultivation mode(P<0.05).In the foregut and midgut of loach,except the alkaline phosphatase(AKP)which was in the foregut in pond cultivation mode,the acid phosphatase(ACP),AKP,superoxide dismutase(SOD)and lysozyme(LZM)were higher in paddy cultivation mode.4 Amino acid composition analysisThere were six types amino acids with content being over 1(g/100g fresh meat)in both cultivation modes,it were asparaginic acid,glutamic acid,alanine,leucine,lysine and arginine.The proportion of essential amino acids in muscle in paddy cultivation mode were slight higher than that of in pond cultivation mode,and the content of valine and tyrosine were higher than that of in pond cultivation mode.Moreover,the content of flavour amino acid(DAA)had no difference in two cultivation modes.