| Poultry is the important source of animal protein for humans.Modern poultry production pursues high production performance and low input costs,which requires more precise diet formulations.Corn is the main energy material in diets,and there is a certain amount of resistant starch in natural corn.Resistant starch has an anti-enzymatic structure,which cannot be degraded into monosaccharides and absorbed by the intestinal tract,but can be utilized by microbial metabolism.In addition to promoting the absorption of fat-soluble nutrients,bile acids also regulate many metabolic processes,including glucose metabolism,lipid metabolism and energy metabolism,and are of great significance for maintaining the body’s metabolic homeostasis.Disorders of bile acid metabolism will not only affect the body’s immune regulation and cause intestinal diseases,but also cause abnormal glucose and lipid metabolism,leading to fatty liver and other diseases.However,the effect of corn resistant starch on the metabolism of bile acids in broilers is still unclear.This experiment studied the changes of corn resistant starch on broiler performance,blood lipid level and ileal content bile acid profile,combined with the effect of corn resistant starch on the ileal intestinal flora,bile acid synthesis and enterohepatic circulation,in order to feed broilers scientific preparation provides reference basis.Experiment 1: The effect of corn resistant starch on broiler chicken growth performance,blood lipid level,total liver bile acid and bile acid profile of ileum content.In this experiment,a total of 80 male Ross 308 broiler chickens were randomly allocated into two groups,with five cages per group and eight birds per cage.The control group was fed corn and soybean meal basal diet,and the test group was fed 4% corn resistant starch diet,and the experimental period was 42 days.The results are showed bellow that corn resistant starch had no significant effect on the average feed intake,average daily gain and feed/gain ratio of broilers(P>0.05).Corn resistant starch can significantly reduce the concentration of total cholesterol,total triglycerides,low-density lipoprotein cholesterol and high-density lipoprotein cholesterol in broiler serum(P<0.05).Corn resistant starch can significantly reduce the concentration of total cholesterol in the liver of broilers,and can significantly increase the concentration of total bile acids in the liver of broilers(P<0.05).Corn resistant starch has no significant effect on the total triglycerides in the liver(P>0.05).Corn resistant starch can significantly increase the total bile acid content in the jejunum content of broilers(P<0.05).Corn resistant starch significantly increased the content of chenodeoxycholic acid,cholic acid,taurocholic acid,allocholic acid,3-dehydrocholic acid,and 12-dehydrocholic acid in the ileal contents(P<0.05).The results showed that corn resistant starch had no significant effect on the growth performance of broilers.It can reduce the blood lipid content of broilers,increase the content of bile acid in the liver,increase the content of free bile acid in the ileum content,and change the bile acid profile of the ileum content.Experiment 2: Effect of corn resistant starch on bile acid metabolism and ileum intestinal flora in broilersThe experiment design is the same as experiment 1.The results are shown bellow that corn resistant starch can significantly increase the content of sterol 27-hydroxylase(CYP27A1),and reduce the content of cholesterol 7α-hydroylase(CYP7A1)and sterol12α-hydroxylation(CYP8B1)(P<0.05).Corn resistant starch had no significant effect on the content of oxysterol 7α-hydroxylase(CYP7B1)(P>0.05).Corn resistant starch had no significant effect on the m RNA expression of bile acid transporters BSEP and MRP2 in rhe level of broiler(P>0.05).Corn resistant starch can significantly reduce the m RNA expression levels of NTCP and OATP1(P<0.05).Corn resistant starch can significantly increase the m RNA expression level of FXR in the liver and reduce the m RNA expression level of LRH-1 in the liver(P<0.05).There was no significant effect on the m RNA expression level of SHP(P>0.05).Corn resistant starch had no significant effect on the m RNA expression levels of ileum FXR,FGF19 and FGFR4 in the liver(P>0.05).Corn resistant starch had no significant effect on the number of Bifidobacterium,Lactobacillus,Bacteroides fragilis,Clostridium XI and Escherichia coli in the ileum of broilers(P>0.05),but could significantly reduce the number of Clostridium XIVa(P<0.05).The results show that corn resistant starch reduces the expression level of bile acid transporter uptake by the liver,and alleviates liver damage caused by the increase of bile acid content in the liver.Corn resistant starch activates the FXR-LRH-1 signaling pathway,thereby reducing the content of bile acid synthase exerts the negative feedback regulation effect of FXR on bile acids.Corn resistant starch can affect the structure of the ileal intestinal flora,reduce the number of Clostridium XIVa,and reduce the production of secondary bile acids.In summary,corn resistant starch has no significant effect on the growth performance of broilers,but it can reduce the blood lipid content of broilers,increase the content of bile acid in the liver,significantly increase the free bile acid content of the ileum content,and change the bile acid composition of the ileum content.Corn resistant starch reduces the reabsorption of bile acids by regulating the expression of bile acid transporters;by activating the FXR-LRH-1 signaling pathway,negative feedback inhibits the synthesis of bile acids.Corn resistant starch can affect the structure of the ileal intestinal flora,reduce the number of Clostridium XIVa,and reduce the production of secondary bile acids. |
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