Antibacterial Effect Of Znic-Bearing Palygorskite In Vitro And Effect Of Its On Growth Performance,Intestinal Physical Barrier And Immune Function In Weaned Piglets

Zinc-bearing palygorskite(Zn-Pal)is an inorganic antibacterial agents that prepared by loaded zinc ion with antibacterial ability on palygorskite(Pal).However,whether the Zn-Pal can be used as an alternative to antibiotics and ZnO in weaned piglets feed is rarely reported.Zn-Pal in the experiment was prepared by solid-state ion exchange method.The aims of this study were to evalaute antibacterial effects of Zn-Pal on three kinds of common swine pathogenic bacteria in vitro and effects of its as an alteranative to antibiotic and ZnO on growth performance,intestinal physical barrier and immune function in weaned piglets.The experiments were divided into three parts.Experiment 1 Study on the antibacterial effects of zinc-bearing palygorskite on three common swine pathogenic bacteria in vitroThe experiment investigated the antibacterial effects of Zn-Pal on in vitro.The results showed that Zn-Pal had inhibitory effects on Escherichia coli,Salmonella typhimurium and Staphylococcus aureus,and the minimum inhibitory concentrations(MIC)were 60,17.5 and 15 mg/mL,corresponding zinc levels were 1.21,0.35 and 0.30 mg/mL,respectively.The results indicated that Zn-Pal has good antibacterial effect and does effect.Experiment 2 Effects of zinc-bearing palygorskite on growth performance,intestinal physical barrier function and the contents of fecal bacterial flora in weaned pigletsThe study investigated the effects of Zn-Pal as an alternative to antibiotic and ZnO on growth performance,intestinal physical barrier and fecal bacterial flora contents in weaned piglets.A total of 128 25-day-old hybird weaned piglets(Duroc × Landrance × Large white)with an average initial body weight of 8.59±0.40 kg were randomly divided into four groups with four replicates and eight piglets per replicate.The piglets were fed the basal diet supplemented with 110 mg/kg kitasamycin and 2 g/kg ZnO(control group,Zn from ZnO 1,600 mg/kg),55 mg/kg kitasamycin,1 g/kg ZnO and 2 g/kg Zn-Pal(Exp.group Ⅰ,Zn from ZnO 800 mg/kg and from Zn-Pal 40 mg/kg),2 g/kg Zn-Pal(Exp.group Ⅱ,Zn from Zn-Pal 40 mg/kg),and 4 g/kg Zn-Pal(Exp.group Ⅲ,Zn from Zn-Pal 80 mg/kg),respectively.The experiment last for 35 days including 7 d pre-test and 28 d test.The results showed that:(1)Zn-Pal did not affect the total weight gain(TWG),total feed intake(TFI)and feed efficiency ratio(FER)of piglets(P>0.05).(2)Compared with the control group,Exp.I and Ⅲ group both had no significant difference on endotoxin content and diamine oxidase(DAO)activity of serum(P>0.05).(3)There were no significant difference on the number of goblet cells in jejunal and ileal epithelium between the Exp.Ⅲgroup and the control group(P>0.05).(4)Zn-Pal did not affect the relative mRNA expression of claudin-1(CLDN-1)in intestinal mucosa and zonula occludens-1(ZO-1)relative mRNA expression of ileal mucosa(P>0.05).Compared with control group,the relative mRNA expression of occludin(OCLN)in jejunal,ileal and caecal mucosa and the ZO-1 relative mRNA expression of jejunal,caecal and colonic mucosa in Exp.Ⅲ group had no significant difference(P>0.05).There were no significant difference on the relative mRNA expressions of ZO-1 and OCLN in jejunal and caecal mucosa between Exp.I and II group(P>0.05).(5)Compared with the control group,Exp.Ⅲ group showed no significant changes on the contents of fecal Clostridium cluster ⅩⅣa and Lactobacillus on d 1,7,14 and 28,and the contents of total bacteria and Escherichia coli of fecal on d 28(P>0.05).The contents of Escherichia coli in fecal on d 1 and 28 in the Exp.Ⅲ group were significantly lower than those in the Exp.Ⅱ group(P<0.05),while the contents of Clostridium cluster ⅩⅣa and Lactobacillus in fecal on d 1 and 28 in the Exp.Ⅲ group were significantly higher than those in the Exp.II group(P<0.05),respectively The results indicated that Zn-Pal as an alternative to antibiotic and ZnO had no significant effect on growth performance,and could maintain the intestinal physical barrier function and the balance of bacterium in piglets.Experiment 3 Effects of zinc-bearing palygorskite on serum and intestinal function and the intestinal concentration of volatile fatty acids in weaned pigletsThe present study was conducted to investigate the effects of Zn-Pal as an alternative to antibiotic and ZnO on serum and intestinal immune index,the mRNA expression of intestinal cytokines and the intestinal concentration of volatile fatty acids in weaned piglets.The experimental animals and design were the same as Experiment 2.The results showed as followed:(1)There were no significant differences on the contents of serum immunoglobulin A(IgA),immunoglobulin M(IgM)and immunoglobulin G(IgG)between the Exp.Ⅲ group and the control group(P>0.05).(2)Compared with the control group,the contents of secreted immunoglobulin A(slgA)and transforming growth factor-β(TGF-β)in ileal and caecal mucosa had no significant changes in the Exp.Ⅲ group(P>0.05),however,there were significantly higher than those in the Exp.Ⅱ group(P<0.05).Compared with the control group,the other experiment groups had no effect on the content of interleukin-10(IL-10)in caecal mucosa(P>0.05).The contents of interleukin-1β(IL-1β)and tumor necrosis factor-a(TNF-α)in jejunal mucosa in the Exp.Ⅲ group were not significant different from that in the control group(P>0.05).There were no significant differences on the contents of IL-1β,IL-10,TNF-α and TGF-β in colonic mucosa between the Exp.Ⅱ and Ⅲ group(P>0.05).(3)The relative mRNA expression of IL-10 in intestinal mucosa between the Exp.I and Ⅲ group were not significant different from those in the control group(P>0.05).Zn-Pal had no siginificant effects on the the relative mRNA expression of IL-1β in jejunal and caecal mucosa,the the relative mRNA expression of TNF-α in jejunal and ileal mucosa and the relative mRNA expression of TGF-β in ileum mucosa(P>0.05).Compared with the control group,the other experiment groups had no significant effect on the relative mRNA expression of IL-1β in ileal mucosa and the relative mRNA expressions of TGF-β and TNF-α in caecal mucosa(P>0.05).The relative mRNA expression of TGF-β in jejunal and colonic mucosa in the Exp.Ⅲ group was not.significantly different compared with those of the Exp.Ⅰ and Ⅱ group(P>0.05).(4)Compared with the control group,the other experiment groups had no significant difference on the concentrations of acetic acid and valeric acid in caecum chyme and the concentrations of acetic acid and propionic acid in colon chyme(P>0.05).The concentrations of propionic acid,butyric acid and total volatile fatty acid in caecal chyme and valeric acid in colonic chyme in the Exp.Ⅲ group were no significant difference compared with the control group(P>0.05).The concentrations of isobutyric acid and isovaleric acid in caecal and colonic chyme in the Exp.Ⅲ group were significantly lower than those in the control group(P>0.05).The results suggested that Zn-Pal could replace to antibiotic and ZnO to maintain the intestinal immune function,and increase the concentration of intestinal volatile fatty acids and improve the intestinal health.