Effects Of Galacto-oligosaccharides On Small Intestine Morphology,Digestion And Absorption And Barrier Function In Weaned Piglets

In order to save the feeding costs and increase productivity of the sow,we now advocate early weaning of piglets.However weaning will cause piglet intestinal villi shrinkage,impaired barrier function and imbalance of intestinal flora structure.Eventually,the piglet’s resistance will reduce and disease will occur,which will reduce growth performance of piglets.In recent years,studies have found that many oligosaccharides can alleviate weaning stress syndrome,and the most recognized one is galacto-oligosaccharides(GOS).As a functional oligosaccharide,GOS has the functions of increasing the height of intestinal villi,promoting the proliferation of beneficial bacteria in the intestine,Lactobacillus and bifidobacteria,helping the development of the immune system and regulating the composition of intestinal microorganisms.In addition,GOS is currently the most widely used oligosaccharides in infant formula and have the property of regulating intestinal function.However,there are few applications of GOS in piglets.The small intestine,as the largest digestive organ and immune organ of piglets,plays an important role in the growth and development of piglets,while the research about effects of GOS on small intestine microorganism is still limited.And so far,few studies have used GOS to intervene in piglets at different stages.Therefore,we explored the effects of GOS on the morphology,digestion and absorption,barrier function and immune function of jejunum and ileum of weaned piglets,as well as the ileal microbial composition by adding GOS at different growth stages.It provides a certain theoretical basis for the application of GOS in the study of nutrition regulation of piglets.This research is mainly divided into the following three parts:1.Effect of different galacto-oligosaccharides intervention stages on the morphology,digestion and absorption of small intestine of weaned pigletsThe aim of this chapter was to investigate the effects of GOS intervention at different stages on the morphology,structure,and digestion and absorption of jejunum and ileum of weaned piglets.120 newborn piglets of Duroc × Landrac × Yorkshire were selected and divided into 4 groups according to birth weight.Each group have 30 piglets,which were selected as control group(CC group),post-weaning treatment group(CT group),pre-weaning treatment group(TC group)and pre-weaning+post-weaning treatment group(TT group).In the first week of piglet birth,the TC and TT groups were fed with 5 mL of GOS solution each time,once in the morning and evening.GOS solutions with different concentrations were prepared according to the weight of piglets,so that the effective daily intake of piglets was 1 g/kg body weight,and the piglets of CC and CT groups were fed with the same amount of saline.Piglets were weaned on day 21,piglets in CC and TC groups were fed a basal diet,and piglets in CT and TT groups were supplemented with 2%GOS in the basal diet.On the 28th day,6 animals were slaughtered in each group,a total of 24 animals were slaughtered.The jejunum and ileum mucosa tissues were taken for determination of related indicators.The results showed that the jejunum weight,villi-crypto ratio,ileum length,lipase and amylase activity in the TC and TT groups were significantly increased(P<0.05),and the jejunum and ileum mucosa invertase activity and ileum villi height were significantly increased(P<0.01),while ileum APA activity was significantly decreased(P<0.05)compared with the CC and CT groups.At the genetic level,early GOS intervention can significantly increase the relative expression of the ileum GLUT2 gene(P<0.05),and significantly increase the relative expression of the jejunal mucosa IGF-1R,ileum mucosa APA,and APN genes(P<0.01),while the relative expression of APA gene in the jejunal mucosa was significantly reduced(P<0.01).The jejunum length,amylase activity,ileum weight,and APN activity of CT and TT groups were significantly increased(P<0.05),and the relative expression of GLP-2 gene in jejunum mucosa was significantly increased(P<0.01)compared with CC and TC groups.In addition,the addition of GOS at different stages had significant interactions on the relative expression levels of the jejunal mucosa IGF-1,GLUT2,APN,PEPT-1 and ileum mucosa SGLT1,DPP4 and ileum mucosa villous-crypto ratio(P<0.05).Under the interaction,villus crypt ratio and the relative expression of SGLT1 in ileum mucosa of CT group,TC and TT groups were significantly higher than those in the CC group(P<0.05).The relative expressions of IGF-1 and GLUT2 in jejunum mucosa of CT group were significantly higher than that in CC group(P<0.05).The amount of APN gene in the jejunum mucosa of the CT group was significantly higher than that of the CC and TT groups(P<0.05).The relative expression of PEPT-1 in jejunum mucosa of TT group was significantly increased(P<0.01)compared with the other three groups.The relative expression of DPP4 in ileal mucosa of TC group was significantly higher than that of the CC and TT groups(P<0.05).The above results show that early GOS intervention can positively affect the intestinal morphology and digestive enzyme activity of the jejunum and ileum,and increase the gene expression levels of GLUT2 and two aminopeptidases in the ileal mucosa at the gene level,which is more conducive to piglets’ digestion and absorption of carbohydrates,fats and proteins in the diet.So piglets are better adapted to the solid diet.2.Effect of different GOS intervention stages on intestinal barrier function and immune function in weaned pigletsThis study was designed to investigate the effects of GOS on jejunal and ileal barrier function and immune function in weaned piglets.The experimental design was the same as that in Chapter 1.The 28-day-old piglets were slaughtered and the jejunum and ileum mucosa were measured for related indicators.The results showed that the relative expression of ZO-1,Occludin,ZO-1,MUC2,TGF-β,TLR2 and TLR4 genes in the jejunal mucosa of TC and TT groups significantly increased(P<0.01),and that the relative expression of IL-1β gene in the ileal mucosa significantly reduced(P<0.01)and that the protein concentration of TNF-α in the ileal mucosa significantly was reduced(P<0.05)compared with the CC and CT groups.The relative expression of Occludin gene and ileal mucosal Occludin protein in piglets of CT and TT groups increased significantly(P<0.05),and the contents of ileal mucosal diamine oxidase and D-lactic acid also significantly increased(P<0.05)compared with the CC and TC groups.The relative expression levels of TLR5 and IL-10 genes in the ileal mucosa were significantly increased(P<0.01),and the relative expression levels of the TNF-α gene were significantly reduced(P<0.01)compared with the CC and TC groups.In addition,the relative expression of MUC2 gene,protein concentrations of sIgA and IL-10,and sIgA concentration in the ileal mucosa at different GOS adding stages produced significant interactions(P<0.05).Under the interaction,the relative expression of MUC2 gene in the jejunal mucosa of weaned piglets in the TT group was significantly higher than that in the CC,CT,and TC groups(P<0.05).The protein concentration of sIgA in the jejunal mucosa of the weaned piglets in the TC group was significantly higher than that in the CC group,In the CT and TT groups(P<0.05),the protein concentration of IL-10 in the TC group was higher than that in the CC group(P<0.05).The protein concentration of sIgA in the ileum mucosa of weaned piglets in the CT and TC groups was significantly higher than that in the CC group(P<0.05).The above results indicate that early GOS intervention mainly increased the expression level of barrier protein genes in the ileal mucosa,and the addition of GOS after weaning mainly affected the barrier function of the ileal mucosa from the protein level.Adding GOS early or after weaning can inhibit the expression of proinflammatory factors in the ileal mucosa,which has a certain strengthening effect on the mucosal barrier function and immune function of the intestine.3.Effect of different galacto-oligosaccharides intervention stages on the bacterial community and metabolites of ileal digesta in weaned pigletsThe purpose of this study was to study the effects of GOS addition on ileal chyme flora and metabolites in weaned piglets at different growth stages.The experimental design was the same as in Chapter 1,ileal chyme was taken to determine the flora structure and the concentration of the flora metabolites.The results showed that the Shannon index(P<0.05),and the relative richness of Proteobacteria,Halomonadaceae,and Rumenococciaceae of the ileal chyme flora of weaned piglets in the CT and TT groups increased significantly compared with the CC and TC groups.The concentrations of acetic acid,isobutyric acid and butyric acid in the ileal chyme in TC and TT groups can significantly increase(P<0.05),and the concentrations of total short chain fatty acids in the ileal chyme significantly increased(P<0.01)compared with the CC and CT groups.In addition,the Simpson index of the ileum chyme of weaned piglets and the relative abundance of the bacterial genus such as Streptococcaceae and Lactobacillus and the metabolites lactate and ammonia nitrogen produced significant interaction.Under the interaction,the Simpson index of the CC,CT and TC groups was significantly lower than that of the CC group(P<0.05).The streptococci of the CT group was significantly lower than that of the CC and TC groups(P<0.05).Lactobacillaceae is significantly higher than CC and TT groups(P<0.05),and Leuconostocaceae of TC group is significantly higher than CC,CT and TT groups(P<0.05).The relative abundance of Micrococcaceae in TT group was significantly higher than that of CC,CT and TC groups(P<0.05).The relative abundance of Streptococcus in CT group was significantly lower than in CC group(P<0.05),and the relative abundance of Clostridium sensu stricto 1 was significantly higher than that of the CC group(P<0.05),and the relative abundance of Lactobacillus was significantly higher than that of the CC and TT groups(P<0.05).The lactate chyme concentration of weaned piglets in the TC group was significantly higher than that in the CC,CT,and TT groups(P<0.05).The ileal chyme ammonia nitrogen concentration in the CT,TC,and TT groups was significantly lower than that in the CC group(P<0.05).The above results indicate that the addition of GOS after weaning increased the microbial diversity of the ileal chyme of the piglets,and changed the bacterial structure of the ileal chyme,and early GOS intervention significantly increased the short-chain fatty acid content of the metabolites of the ileal chyme of the piglets.This strengthens the chemical barrier of the intestine to some extent.