| To explore two kinds of microbiota(fecal microbiota,colonic microbiota)transplantation on newborn piglets’ growth performance,intestinal morphology,structure of intestinal microbiota,immune barrier function and the effect of gut hormone secretion and action mechanism,nine litters of newborn“Landrace×Rongchang” piglets with the same birth date were selected and divided into3 groups with 3 litters in each group and the litter weight at birth was given.On the third day after birth,each piglet in the FMT group was orally fed 1 m L fecal microbiota suspension of healthy adult “Duroc×Landrace×Yorkshire” crossbred pigs per day,piglets in CMT(colonic microbiota transplantation)group were orally fed with 1 m L of colonic microbiota suspension from the same donor every day,and control(CON)group piglets were orally fed with the same amount of sterile normal saline every day.Feed continuously for 5 days,once a day,and the end of 7 days of age.No supplementary feeding before weaning.All piglets were weighed on an empty stomach at the age of 3 days and 28 days.The average daily gain was calculated and the diarrhea rate was calculated.At 28 days of age,venous blood was collected from 6 healthy piglets(6 replicates)with close to average body weight in each group for the determination of blood biochemical indexes,serum hormone levels and inflammatory factors levels.The corresponding intestinal and content samples were slaughtered at the same period and collected for the detection of digestive enzyme activity of intestinal contents,intestinal tissue morphology,intestinal barrier,immune-related protein expression,gene expression of immune-related factors,intestinal microbiota structure,metabolite and related receptor expression,and intestinal hormone expression.The results are as follows:1)Compared with the control group,the average daily gain(ADG)of piglets in FMT group was increased by 36.1%(P<0.01),ADG of piglets in CMT group was increased by about 15.5%,but not to a statistically significant level(P>0.05);The diarrhea rate of piglets in FMT group was decreased by about 45.0%(P<0.01),the diarrhea rate of piglets in CMT group was decreased by about 57.5%(P<0.01),which showed that FMT and CMT accelerated the growth of piglets and reduced diarrhea in different degrees.2)FMT significantly increased the contents of growth hormones(GH),leptin(LEP),insulin(INS)in the blood of piglets(P<0.05);The total amylase activity in colonic contents of piglets was increased by transplanting two kinds of bacteria,which was reflected in the β-amylase activity of piglets in FMT group(P<0.01)and CMT groups increased the α-amylase activity of piglets(P<0.05).In addition,both FMT and CMT increased lipase activity in piglets(P<0.01);The total cholesterol content in blood of piglets was significantly decreased by different bacterial community transplantation(P<0.01)and increased blood glucose(P<0.05);Compared with the control group,the albumin content of piglets in FMT group was significantly increased(P<0.01);There was no significant difference in triglyceride levels among the three groups(P>0.05).These results suggest that the two kinds of microbiota transplantation can promote nutrient intake and accelerate growth,digestion and metabolism of piglets by introducing exogenous probiotics to different degrees.3)The two kinds of microbiota transplantation significantly increased ileum villus height(P<0.01);CMT significantly increased the crypt depth of ileum(P<0.01)and intestinal wall muscular thickness(P<0.01);FMT significantly decreased the number of goblet cells in duodenum of piglets(P<0.05),and CMT had no significant effect on the number of goblet cells in duodenum(P>0.05);CMT significantly increased the protein expression of Occludin in ileum and Claudin-1 in colon of piglets(P<0.01)but there was no significant difference in the expression of mucosal barrier related proteins in FMT group(P>0.05),suggesting that CMT improved the intestinal barrier function of piglets to some extent.4)Serum levels of pro-inflammatory factors IL-6 and TNF-α were significantly increased in FMT group(P<0.05),the mRNA relative expression levels of pBD-2 and mucin MUC2 in intestinal tract were significantly decreased(P<0.01),the expression of TLR2 protein in ileum was significantly decreased(P<0.05),and the mRNA relative expression levels of defensin p G1-5 and mucin MUC2 in intestinal tract of piglets in CMT group were significantly increased(P<0.05),the protein expression of TLR2 in ileum was significantly increased(P<0.01),which suggests that FMT may cause inflammation in piglets and increase the potential risk of intestinal disease,suggesting that donor bacteria should be carefully considered and selected during microbial community transplantation;CMT may improve the function of intestinal immune barrier in piglets.5)The diversity of colonic microbiota of piglets in CMT group decreased.The structure of colonic microbiota of piglets in CON group and FMT group was more similar.The relative abundance of beneficial bacteria in intestinal tract was increased and the number of pathogenic bacteria was decreased.Compared with CON group,both FMT and CMT decreased the relative abundance of Firmicutes and increased the relative abundance of Bacteroidetes.It is suggested that the change of intestinal microbiota caused by different microbial community transplantation can increase the relative abundance of beneficial or functional bacteria,and thus ensure that piglets can better adapt to early feeding of plant solid diet.6)The content of total short chain fatty acids(SCFAs)in piglets’ colon of FMT group increased,and the content of isobutyrate and isopentanoic increased significantly(P<0.05),the mRNA relative expression levels of colon receptor FFAR1,FFAR2 and FFAR3 were significantly up-regulated(P<0.01);There were no significant changes in the contents of SCFAs in colon of CMT group(P>0.05).The mRNA relative expression levels of SCFAs receptor FFAR2 in ileum and SCFAs receptor FFAR1,FFAR2 and FFAR3 in colon were significantly up-regulated(P<0.05),which revealed that the changes of intestinal microbiota caused by the two kinds of microbiota transplantations could accelerate the utilization of nutrients and produce SCFAs,thereby activating the expression of SCFAs receptors.7)The contents of three intestinal hormones of cholecystokinin(CCK),glucagon-like peptide-1(GLP-1),ghrelin in the serum of piglets in the FMT group increased to varying degrees,among which GLP-1,ghrelin,GH,LEP and INS reached significant levels(P<0.05),while the serum hormone levels of piglets in the CMT group did not change significantly(P>0.05);The expression levels of CCK in the ileum of piglets in the FMT group increased significantly(P<0.05),and the mRNA relative expression of CCKAR and CCKBR of CCK receptors also showed an upward-regulated trend.Among them,CCKAR reached a significant level(P<0.05),while ghrelin had no significant level(P>0.05).The mRNA relative expression of GHSR did not change significantly(P>0.05).The expression levels of GLP-1 in the colon were significantly increased(P<0.01),and the mRNA relative expression of the corresponding receptors GLP-1R showed an upward-regulated trend,but the difference was not significant(P>0.05).The expression level of ghrelin decreased significantly(P<0.05),and the relative expression of mRNA of its receptor GHSR was also significantly down-regulated(P<0.01);The expression level of ghrelin in the ileum of piglets in the CMT group was significantly increased(P<0.05),and the relative expression of GHSR mRNA was also significantly increased(P<0.01).The expression level of CCK in the colon increased significantly(P<0.05),the expression level of ghrelin decreased significantly(P<0.05),and the mRNA relative expression of its receptor GHSR was also significantly down-regulated(P<0.05).It suggests that transplantation of two kinds of microbiota can cause fluctuations in intestinal hormones.To conclude,the effects of FMT and CMT on growth and intestinal health of piglets are not the same.The transplantation of the two kinds of microbiota can promote the growth in different degrees of piglets.FMT can obviously promote the growth and development of piglets,but it may increase the risk of intestinal damage and disease in piglets.Although the effect of CMT on the growth and development of piglets is not as obvious as that of FMT,it can improve the intestinal barrier and immune function of piglets,reducing the risk of underlying bowel diseases,and contribute to intestinal health.In addition,transplantation of different flora has caused changes in the composition of the piglet’s intestinal microbiota.This change will also cause fluctuations in the expression levels of intestinal hormones and their receptors in the intestine,and will also activate the expression of SCFAs receptors. |
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