The Effects Of β-glucan On Growth Performance And Intestinal Function Of Weaned Piglets

The purpose of this study is to study the effect of β-glucan isolated from Agrobacterium ZX09 on intestinal microflora,intestinal barrier and immune function of weaned piglets,and the mechanism of β-glucan regulating intestinal inflammatory response of weaned piglets.(1)Experiment 1: Effects of β-glucan on growth performance,immune function and ileum microflora of weaned piglets.144 weaned piglets(Duroc ×(Landrace ×Yorkshire);21 d of age;6.05 ± 0.36kg)were randomly divided into four groups according to body weight,with six replicates in each group,and six pigs in each replicate were fed with the following diet: 1)The control group fed with basal diet without antibiotics;2)The antibiotic group fed with basal diet supplemented with 20mg/kg olaquindox;3)Low glucan group,fed basal diet supplemented with 100 mg /kg β-glucan;4)High glucan group,fed basal diet supplemented with 200 mg / kg β-glucan.3 days of preparatory feeding and 14 days of experiment.Compared with the control group,the weaned piglets fed with 200 mg/kg β-glucan did not affect the production performance of weaned piglets,while the weaned piglets fed with 200 mg /kg β-glucan had higher average daily gain and jejunum villus height:crypt depth ratio(P < 0.05).Compared with 200 mg/kg β-glucan,diet supplemented with olaquindox increased the villus height and crypt depth of duodenum and jejunum of piglets(P <0.05),but had no effect on the villus height:crypt depth ratio(P > 0.05).Compared with the control group,the dietary supplementation of 200 mg/kg β-glucan tended to increase the expression of occludin m RNA on jejunum(0.05<P<0.10).Beta-glucan enriched the relative abundance of Fournierella,Oscillospira,Terrisporobacter and Negativibacillus on ileum(P < 0.05).In conclusion,the dietary supplementation of 200mg/kg β-glucan can increase the abundance of ileal beneficial bacteria and promote the production performance of piglets,which will provide a theoretical basis for the application of β-glucan in weaned piglets.(2)Experiment 2: Effects of dietary β-glucan on growth performance,intestinal morphology and immune response in piglets with lipopolysaccharide-induced inflammation.Thirty-two 21 d weaned piglets(Duroc ×(Landrace × Yorkshire);6.64±0.16 kg)with similar body weight were randomly divided into four treatments according to the diet(control diet or β-glucan diet)and inflammatory treatment(intraperitoneal injection of sterilized saline or LPS),with eight replicates in each treatment,and one pigs in each replicate.Two of them were fed basal diet,and the other two were fed basal diet supplemented with 200 mg / kg β-glucan.On the 39 d of the experiment,a half of pigs treated with every diet were intraperitoneal injected with LPS of 80 μg / kg body weight,and the other half was injected with the same amount of sterilized saline.After 4 h of LPS challenged,the piglets were slaughtered and intestinal samples were collected after anesthesia.The results showed that intraperitoneal injection of LPS significantly increased the number of white blood cells,neutrophils,lymphocytes,monocytes and eosinophils in the whole blood of weaned piglets(P <0.05),decreased the ratio of CD4 +/ CD8+T cells(P < 0.05),significantly increased the concentration of IL-6 in ileum mucosa and IL-1β,s Ig A and NO in serum(P < 0.05).Also,intraperitoneal injection of LPS significantly increased intestinal histopathological injury in weaned piglets(P < 0.05).Dietary supplement with β-glucan significantly decreased the amounts of lymphocytes and eosinophils and significantly decreased the concentration of IL-1β and NO in serum induced by LPS(P < 0.05),and alleviate LPS-induced intestinal histopathological injury(P <0.05).Dietary supplement with β-glucan significantly increased the expression of dectin-1 m RNA in ileal mucosa,peyer’s patch and Intestinal lymph nodes(P< 0.05).Diet supplemented with β-glucan decreased the m RNA expression levels of NF-κB,MYD88 and IL-1β in ileal mucosa and intestinal lymph nodes of piglets treated with LPS(P < 0.05),and significantly decreased the m RNA expression levels of TLR-2 and TNF-α in Peyer’ patches(P <0.05).Dietary β-glucan could reduce the expression levels of p-NF-κB,p-IKKα / β and p-IκB proteins in the ileum of LPS-challenged piglets(P < 0.05).In summary,diet supplemented with β-glucan can alleviate LPS-induced intestinal inflammation and improve intestinal barrier in weaned piglets,its mechanism may be related to the receptor-activated signaling pathway dectin-1-SYK-NF-κB.