| β-Conglycinin is one of the main antigen proteins of soybean and has strong immunogenicity.Too high content of β-Conglycinin in diets has a negative impact on animal health.In order to determine an appropriate threshold of β-conglycinin in formula diets of juvenile Rhynchocypris lagowskii Dybowski.In our study,juvenile R.lagowskii Dybowski with an initial body weight of [(4.61±0.01)g/tail] was used as study object.Fish meal,casein and gelatin were used as protein source.Fish oil and corn oil were used as fat source.5 isonitrogeous and isolipidic diets were formulated into: the content of β-Conglycinin respectively were 0g/kg(CK),20 g/kg(β-20),40 g/kg(β-40),60 g/kg(β-60)and 80 g/kg(β-80),the feeding trial was carried out for 8 weeks.After the end of feeding trial,effects of β-conglycinin on growth performance,digestive enzyme activities,protein metabolism enzyme activities,immune function,inflammation-related gene expression,antioxidant capability and related gene expression,intestinal morphology,intestinal permeability and tight junction protein-related gene expression in R.lagowskii Dybowski were systematically analyzed by using technical methods such as biochemistry,molecular biology and histology,it provides a reference for further study on the sensitization mechanism of β-Conglycinin,and is of great significance for the rational development and utilization of soy protein sources These results shown:1.Effects of β-Conglycinin on the growth performance and feed utilization of R.lagowskii DybowskiUnder the conditions of our study,in β-40,β-60 and β-80 groups,FW,WGR,SGR,FER,PER and the crude protein content of R.lagowskii Dybowski were significantly lower than CK group(P<0.05).2.Effects of β-Conglycinin on the activities of digestive enzymes and protein metabolism enzymes of R.lagowskii DybowskiUnder the conditions of our study,compared with the CK group,the activities of protease in hepatopancreas and PI in β-40,β-60 and β-80 groups were significantly decreased(P<0.05),the activities of protease in MI and DI in β-Conglycinin groups were significantly decreased(P<0.05).However,β-conglycinin had no significant effect on the activities of lipase and amylase in intestines and hepatopancreas(P>0.05).Compared with the CK group,the activities of GPT in hepatopancreas were significantly decreased in β-40,β-60 and β-80 groups(P<0.05),the activities of GPT in serum were significantly increased(P<0.05).However,β-conglycinin had no significant effect on the activities of GOT in hepatopancreas and serum(P>0.05).3.Effects of β-Conglycinin on immune function and inflammation-related gene expression of R.lagowskii DybowskiUnder the conditions of our study,compared with the CK group,the activities of LZM and AKP in serum in β-40,β-60 and β-80 groups were significantly reduced(P<0.05).The content of C3 and C4 in serum in β-60 and β-80 groups were significantly decreased(P<0.05).The content of Ig M in serum in β-60 and β-80 groups were significantly increased(P<0.05).Compared with CK group,the expression of IL-1β in hepatopancreas and DI inβ-Conglycinin groups were significantly increased(P<0.05),the expression of IL-1β in PI and MI in β-40,β-60 and β-80 groups were significantly increased(P>0.05).The expression of TNF-α in hepatopancreas,PI,MI and DI in β-Conglycinin groups were significantly increased(P<0.05).The expression of IL-10 and TGF-β in hepatopancreas,PI,MI and DI inβ-Conglycinin groups were significantly decreased(P<0.05).4.Effects of β-Conglycinin on antioxidant capacity and related gene expression of R.lagowskii DybowskiUnder the conditions of our study,compared with CK group,the content of MDA in hepatopancreas,PI,MI and DI in β-40,β-60 and β-80 groups were significantly increased(P<0.05).The activities of CAT in hepatopancreas and PI in β-40,β-60 and β-80 groups were significantly reduced(P<0.05),in MI and DI in β-60 and β-80 groups were significantly decreased(P<0.05).The activities of GSH-PX in hepatopancreas,PI,MI and DI inβ-40,β-60 and β-80 groups were significantly reduced(P<0.05).The activities of T-SOD in PI,MI and DI in β-40,β-60 and β-80 groups were significantly reduced(P<0.05),in hepatopancreas in β-60 and β-80 groups were significantly decreased(P<0.05).Compared with CK group,the expression of Nrf2,HO-1,CAT and GSH-PX in hepatopancreas,PI,MI and DI in β-Conglycinin groups were significantly decreased(P<0.05),the expression of Keap1 in hepatopancreas,PI,MI and DI in β-Conglycinin groups were significantly increased(P<0.05).5.Effects of β-Conglycinin on intestinal tissue and intestinal permeability of R.lagowskii DybowskiUnder the conditions of our study,compared with CK group,the fold height of PI and MI in β-40,β-60 and β-80 groups were significantly reduced(P<0.05),the fold height of DI inβ-Conglycinin groups were significantly lower than CK group(P<0.05).The lamina propria width of PI in β-60 and β-80 groups were significantly increased(P<0.05),the lamina propria width of MI in β-40,β-60 and β-80 groups were significantly increased(P<0.05),the lamina propria width of DI in β-Conglycinin groups were significantly increased(P<0.05).The muscular layer thickness of PI and DI in β-40,β-60 and β-80 groups were significantly reduced(P<0.05),the muscular layer thickness of MI in β-Conglycinin groups significantly reduced(P<0.05).In CK group,the structure of PI,MI and DI of R.lagowski Dybowski were clear and complete,the intestinal villi were well developed,the striated margins were arranged neatly,the muscular layer was thick,and the serosa was intact.In β-20 group,the intestinal villi of DI were broken.In β-40 group,the intestinal villi of PI were broken and MI showed obvious villi atrophy.In β-60 group,the lamina propria of PI was separated and the lamina propria of DI was significantly widened.In β-80 group,the lamina propria of PI was separated and DI showed obvious villi atrophy.Compared with CK group,the levels of 5-HT,ET-1 and D-LA and the activities of DAO were significantly increased in serum of R.lagowski Dybowski(P<0.05);the expression of Occludin-a in PI,MI and DI in β-Conglycinin groups were significantly decreased(P<0.05);the expression of Occludin-b in PI were significantly decreased in β-60 and β-80 groups(P<0.05),in MI and DI were significantly reduced in β-Conglycinin groups(P<0.05);the expression of Claudin in PI and MI in β-40,β-60 and β-80 groups were decreased significantly(P<0.05),in DI were significantly reduced in β-Conglycinin groups(P<0.05);in PI,the expression of ZO-1 were significantly increased in β-20 and β-40 groups(P<0.05),in β-60 and β-80 groups were significantly decreased(P<0.05);in MI,the expression of ZO-1 in β-20 group were significantly increased(P<0.05),in β-40,β-60 and β-80 groups were significantly decreased(P<0.05),in DI were significantly decreased in β-Conglycinin groups(P<0.05).According to the above results,when the content of β-Conglycinin in diet exceeds 20 g/kg,tthe growth performance,antioxidant capacity and immune function were suppressed,the digestion and absorption were disturbed,intestinal injury and intestinal inflammation were caused,intestinal permeability was increased,the structure of tight junction protein was destroyed in R.lagowskii Dybowski.In the formulated diets of R.lagowskii Dybowski,the content of β-Conglycinin should not exceed 20 g/kg. |
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