| In this study,the initial body weight of(20.00±0.02)g M.Albus was used as the experimental object fed with the normal fish meal group(42% fish meal + 22% soybean meal,FM group)and two low fish meal,high soybean protein feed groups: soybean meal feed group(22% fish meal + 52% soybean meal,SBM group),soybean protein concentrate feed group(22% fish meal + 35.6% soy protein concentrate,SPC group).The experiment aims to explore the effects of adding cholesterol to the low fish meal and high soybean protein feed on the growth,lipid metabolism and intestinal health of M.Albus.The main research methods and results are as follows:1.Effects of cholesterol supplementation in high soybean meal feed on growth,lipid metabolism and intestinal health of M.AlbusIn the high soybean meal group,5 g/kg(SBC5)and 10 g/kg(SBC10)of cholesterol were added.the result shows:1)Compared with the FM group,high soybean meal diet significantly reduced M.Albus weight gain rate(WGR)and Hepatosomatic index(HSI)(P<0.05).Adding 10 g/kg cholesterol(SBC10)to the high soybean meal diet can significantly increase the weight gain rate(P<0.05)but still significantly lower than the FM group(P<0.05),and has no significant effect on the Hepatosomatic index(P>0.05).2)Compared with the FM group,the activities of serum aspartate aminotransferase(AST)and alanine aminotransferase(ALT)in the SBM group were significantly increased(P<0.05),and the contents of blood ammonia(BA)and urea nitrogen(BUN)were significantly decreased(P<0.05).).After supplementing cholesterol,the serum BA and acid phosphatase(ACP)contents of M.Albus.were significantly increased,while the activities of AST and ALT decreased(P<0.05).Compared with the FM group,the serum total cholesterol(TC),low-density lipoprotein cholesterol(LDL-c),liver and intestinal high-density lipoprotein cholesterol(HDL-c)contents of M.Albus.in the SBM group decreased.The contents of TC,LDL-c,free fatty acid(NEFA),liver and intestinal HDL-c were significantly increased(P<0.05),and serum triglyceride(TG)contents were decreased.3)Compared with the FM group,the hindgut villi in the SBM group were shru nken,the serosa fell off and the muscular layer was thinned,the gastric gland cells i n the gastric mucosa were sparsely arranged,and the striatum was defective and disc ontinuous.However,after supplementing cholesterol,the height of villus,the thicknes s of the muscle layer and the number of goblet cells in the hindgut of M.Albus inc reased(P<0.05),the gastric mucosal folds were intact and high and the AMS activit y in the stomach of M.Albus returned to the normal level of fish meal(P<0.05).A nd intestinal sodium-potassium ATPase and amylase(AMS)activities were enhanced(P<0.05).The dominant bacterial phyla in the intestinal tract of M.Albus in each gr oup were Firmicutes,Fusobacterium and Proteobacteria,and the dominant bacterial ge nera were Clostridium and Proteobacteria.Compared with the SBM group,the SBC10 group significantly improved the Chao1 index of the intestinal flora of M.Albus(P<0.05)and the relative abundance of beneficial bacteria(Firmicutes,Rombutzia)inc reased;compared with the SBM group,Through the prediction and analysis of the f unction of the hindgut microflora of M.Albus,the SBC10 group of intestinal microb es promoted carbohydrate,amino acid metabolism,cell repair and damage.In conlusion,supplementing 10 g/kg cholesterol in high soybean meal feed had the best effect,promoting the growth performance of M.Albus,improving the lipid metabolism of M.Albus ’s liver,and improving the beneficial bacteria(Firmicutes,Rombutzia)in the hindgut relative abundance and improved intestinal mucosal morphology.2.Effects of cholesterol supplementation in soybean protein concentrate feed on growth,lipid metabolism and intestinal health of M.AlbusBased on Experiment 1,this experiment studied the effect of the modified soybean meal(soy protein concentrate)to replace fish meal,and further increased the amount of cholesterol added.10 g/kg(SPC10)and 20 g/kg(SPC20)of cholesterol were added to the SPC feed,respectively.The experimental results are as follows:1)Compared with the SPC group,after adding 10 g/kg cholesterol(SPC10)to the high soybean protein concentrate diet,M.Albus WGR and Condition factor(CF)were significantly improved and significantly higher than those in the FM group(P<0.05).2)Compared with the FM group,the serum AST activity and BA content of M.Albus in the SPC group were increased(P<0.05),and the glucose(GLU)content in the blood glucose serum was significantly decreased(P<0.05).Compared with the SPC group,after supplementing cholesterol,the serum ACP and GLU contents and the liver ALT activity were significantly increased(P<0.05),and the serum AST activity was significantly decreased(P<0.05).Compared with the FM group,the content of TC and HDL-c in the liver and the content of TC in the serum of M.Albus in the high soybean meal group were significantly decreased(P<0.05),and the content of TG,TC and LDL-c in the serum of the eel after adding cholesterol was significantly increased(P<0.05).),the contents of TC and HDL-c in the liver were significantly increased(P<0.05),and the content of LDL-c in the intestine was increased.3)Compared with the FM group,the intestinal villi of M.Albus in the SPC group were shed and the thickness of the muscularis layer was significantly reduced(P<0.05),the gastric mucosal epithelium was densely packed with columnar cells,the gastric gland cells were sparsely arranged;The arrangement of intestinal villi recovered neatly,the height of villi and the number of goblet cells were significantly higher than those in the SPC group,the gastric striatum was intact and continuous,the gland cells were closely arranged and evenly distributed,the mucosal folds were wider,and the activity of gastric amylase was also significantly increased(P<0.05).The dominant bacterial phyla in the intestinal tract of M.Albus in each group were Firmicutes,Fusobacterium and Proteobacteria,and the dominant bacterial genera were Clostridium,Cetobacter and Streptococcus.Compared with the SPC group,the relative abundance of Firmicutes,which can improve intestinal health,was increased in the hindgut of the SPC10 group and SPC20 group.Compared with the SPC group,by predicting the function of the hindgut flora of M.Albus,supplementation of 10g/kg and 20 g/kg cholesterol in the high soybean protein concentrate feed promoted the bacterial chemotaxis,glutamate and alanine metabolism,Fatty acid synthesis and other.In conclusion,supplementation of 10 g/kg and 20 g/kg cholesterol in high soybean protein concentrate feed can promote the growth of M.Albus,improve the lipid metabolism capacity of the liver of M.Albus,increase the relative abundance of Firmicutes in the hindgut of M.Albus,and increase the Digestive enzyme activity,improve the intestinal mucosal morphology of M.Albus. |
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