| Excessive protein intake will increase the protein fermentation of intestinal microbes,causing the intestinal microflora and immune function of animals,especially young animals,to be significantly affected,and the production performance will be reduced accordingly.In addition,animal nitrogen emissions will increase significantly,resulting in Serious environmental pollution and waste of protein resources.In this experiment,SD rats were used as animal models to design high-protein diets at different levels.The aim was to study the effects of high-protein diets on the metabolism of SD rats,intestinal microflora,and intestinal immune function.The diet for poultry,especially weaned piglets,provides a scientific reference.The research content is divided into the following three experiments:Experiment 1: effect of high protein diet on substance metabolism of SD ratsEighty healthy 42 days old SD male rats(180-200 g)were randomly divided into four groups.Each group was fed with different levels of protein,including 20% CP(control),28% CP,38% CP and 50% CP.each group had four replicates,five replicates each,and the experimental period was 42 days.The results showed that:(1)High protein diets(28% CP,38% CP,50% CP)significantly reduced the average daily weight gain of SD rats(P <0.05);compared with the control group,the feed weight ratio of the 50% CP group was significantly increased(P <0.05),epididymal fat and bilateral perirenal fat weight were significantly reduced(P <0.05).(2)The serum glutamate aminotransferase and aspartate aminotransferase activities of SD rats in 50%CP group were significantly higher than those in other groups(P <0.05);38% CP,50%CP group significantly reduced total cholesterol,Triglycerides and high-density lipoprotein cholesterol(P <0.05).(3)Compared with the control group,the blood neutrophil ratio and lymphocyte number of SD rats in the 28% CP and 38% CP groups were significantly increased(P <0.05),38% CP and 50% CP group SD rats The neutrophils were significantly reduced(P <0.05).(4)Compared with the control group,the serum neuropeptide-Y and adiponectin contents of SD rats in the 50% CP group were significantly increased(P <0.05);the fasting insulin content and insulin resistance in the 38% CP group were significantly lower than those of the other three Group(P<0.05).(5)The relative expression levels of p-AMPK2? and ACC-1 protein in SD rat liver in 50% CP group were significantly higher than those in other groups,and the relative expression levels of AMPK2? and p-ACC-1 protein were significantly lowerthan those in other groups(P <0.05)The relative expression levels of SEBRP-1 and p-SEBRP-1 protein in SD rats in the 38% CP group were significantly higher than those in the control group(P <0.05);compared with the control group,high protein diets(28% CP,38% CP),50% CP)The relative expression level of CPT-1 protein in SD rat liver decreased(P <0.05).(6)Relative to the control group,increasing the dietary protein level mainly changed the fatty acid and phospholipid substances in the colonic mucosa of SD rats.The concentration of most saturated fatty acids such as palmitic acid,stearic acid and behenic acid in the experiment Relative to the control group,lipids such as glycerin and various phospholipids showed the same trend.Compared with the control group,the expression of fucose in the colon content of the38% CP group decreased,but the expression of the 50% CP group did not change significantly.Experiment 2: effect of high protein diet on intestinal immune function of SD rats80 healthy 42 days old SD male rats(180-200 g)were selected.The experimental design was consistent with that of Experiment 1.On the last day of the experimental period,colonic tissue and mucosa were collected to determine the morphological structure of intestinal mucosa,the degree of intestinal damage,immune-related factors,and colon mucosa barrier related proteins.(1)Compared with the control group,the50% CP group significantly increased the height of colonic villi in SD rats(P <0.05);the 38% CP group significantly reduced the depth of colonic crypts and the height of villi/crypt depth(P <0.05);The ileal villi height/crypt depth and goblet cell number of SD rats with 50% CP were significantly increased compared with the control group(P<0.05).(2)The intestinal DAO content of SD rats with high protein diets(28% CP,38% CP,50% CP)increased significantly(P <0.05);high protein diets(28% CP,38%CP,50% CP)significantly increased immunoglobulin G and immunoglobulin M in colonic mucosa of SD rats;compared with the control group,50% CP group had transforming growth factor-?,tumor necrosis factor-?,and 28% CP group interleukin 6 The content was significantly increased(P <0.05);the content of secreted immunoglobulin A and interleukin-8 in the 28% CP group was significantly higher than that of the other groups(P <0.05).(4)SD rats ingested high protein diets(28% CP,38% CP,50% CP).The relative expression of NF-?B and TLR-4 protein in colonic mucosa was significantly reduced(P <0.05),38% CP group The relative expression level of RIP-2 protein in colonic mucosa was significantly higher than that in other groups(P <0.05).(5)The number of B cells and NK cells in the blood of SD rats in the50% CP group increased significantly(P <0.05);high protein diets(28% CP,38% CP,50% CP)significantly reduced the expression of colon NK cells Level(P <0.05).Compared with the control group,the 50% CP group significantly increased the number of CD4 and CD8 cells in the colon and decreased the number of CD3 cells.(P<0.05).Experiment 3: effect of high protein diet on the intestinal microflora of SD rats.Eighty 180-200 g healthy 42 days old SD male rats were selected.The experimental design was consistent with experiment one.On the last day of the experimental period,six rats were randomly selected from each group,24 rats in total,and colonic contents were collected.The results showed that 38% of CP Group had the highest expression of sclerotia at the gate level.With the increase of dietary protein level,the relative abundance of Bacteroides decreased first and then increased,20% CP Group and 50% CP Group In CP Group,the relative abundance of Bacteroides was almost the same,while that of Proteus,verruca,and actinomycetes increased first and then decreased.At the class level,with the increase of dietary protein level,the relative abundance of Bacteroides is the same as that of the phylum level.The relative abundance of spirochetes increased first and then decreased.Verrucosa was only detected in 20%,38% and 50% CP groups,and the relative abundance of microorganisms increased with the increase of dietary protein level.In conclusion,High-protein diet(28%,38%,50% CP)significantly reduced the daily gain of SD rats;high-protein diet(38% CP,50% CP)reduced the body's organ fat deposits and lowered the fatty acids of colonic mucosa And metabolic substances such as phospholipids and various regulating enzymes that regulate fat synthesis pathways to improve the body's lipid metabolism;high protein diets(28%,38%,50% CP)significantly reduce NF-?B,TLR-4 protein expression,improve DAO activity,reduce intestinal mucosal epithelial cell damage,high protein diet(28%,38% CP,50% CP)SD rat colon mucosal immune-related factors significantly increased,peripheral blood The number of B cell subtype differentiation increased significantly,the number of colon NK cell subtype differentiation significantly decreased,the body's inflammatory response increased,and the intestinal mucosal immune function was reduced;high protein diet(28% CP)made the SD rat colon microflora structure More abundant,the relative abundance of microorganisms increased significantly. |
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