Effects Of Zinc-loaded Montmorillonite On Metal Element Deposition,Antioxidant Function,Nutrient Transport And Barrier Function In Small Intestine Of Broilers

This experiment was conducted to investigate the effects of zinc-montmorillonite（Zn-MMT）on performance,intestinal morphology,antioxidant activity,microelement deposition,intestinal physical barrier and nutrient transporter gene expression of broilers with corn-soybean meal based diet as reference.This study aims to broaden the source of zinc in feed and provide a scientific basis for rational utilization of zinc-loaded montmorillonite in broilers.This study includes three parts:Experiment 1 Effects of Zn-MMT on performance,immune organ index and intestinal tissue morphology of broilers.A total of 288 1-day-old male cob broiler were randomly assigned to 6 groups with 6 replicates per group and 8 birds per replicate.The birds were fed a corn-soybean meal basal diet or one of the four Zn-MMT diets or Zn SO₄ diets,which were the basal diet supplemented with 20,40,60,80 mg/kg Zn-MMT（Zinc content measurement）.The Chickens were free to feed and drink.The results showed as follows:1)Compared with CK group and Zn SO₄group,Zn-MMT had no significant effect on average daily feed intake of broiler chickens（P>0.05）.However,80 mg/kg Zn-MMT significantly reduced the average daily gain（P<0.05）,and 40 mg/kg Zn-MMT significantly reduced the feed to gain ratio of chicks aged 1～42 days（P<0.05）.2)Compared with CK group,60 mg/kg Zn-MMT significantly increased the bursa index of broilers（P<0.05）.3)compared with CK group,Zn-MMT had no significant effect on the slaughter performance of broilers（P>0.05）.4)Compared with CK and Zn SO₄ groups,40 mg/kg Zn-MMT significantly increased villus height and villi height to crypt depth ratioof the duodenum and jejunum（P<0.05）,and significantly reduced the crypt depth of the duodenum（P<0.05）,but had no significant effect on the ilealnd jejunum crypt depth（P>0.05）.Experiment 2 Effects of Zn-MMT on metal deposition in tissue,zinc-containing enzyme activity in liver and antioxidant capacity of broilers.A total of 144 1-day-old male cob broilers were randomly assigned to 3 groups with 6 replicates per group and8 birds per replicate.The broilers in the experimental control group were fed a corn-soybean meal basal diet,and those in the positive control group were fed the basal diet supplemented with 40mg/kg Zn SO₄,while those in the experimental groups were fed the basal diet supplemented with 40mg/kg Zn-MMT（Zinc content measurement）.The Chickens were free to feed and drink.The results showed as follows:1)Compared with CK group,Zn-MMT groups significantly increased the deposition of iron in breast muscle at 42 days of age（P<0.05）.At the same time,Zn-MMT not only increased the zinc content of pancreas at 21 days of age,but also increased the zinc content of liver,tibia,pancreas and whole blood at 42 days of age（P<0.05）.What’s more,compared with Zn SO₄ group,Zn-MMT significantly increased the deposition of iron in breast muscle and copper,manganese and zinc in liver at 42 days of age,as well as the deposition of zinc in pancreas at 21 and 42 days of age,and increased zinc deposition in the tibia at 21 days of age（P<0.05）.2)Compared with CK group,Zn-MMT had no significant effects on LDH,MDH and ALP in liver of broilers（P>0.05）.3)Compared with CK group,Zn-MMT and Zn SO₄groups significantly increased the enzyme activities of T-AOC and Cu Zn SOD in liver and jejunum of broilers（P<0.05）,and decreased the content of MDA（P<0.05）.4)Compared with CK and Zn SO₄ group,Zn-MMT significantly increased the MT and MT3 m RNA expression in liver（P<0.05）,but had no significant effect on the MT and MT3 m RNA expression in pancreas（P>0.05）.Experiment 3 Effects of Zn-MMT on the expression of nutrient transporters and intestinal barrier related gene on small intestine in broilers.The experiment design is the same as experiment 2.The results showed as follows:1)Compared with CK group,Zn-MMT significantly increased Zn T-1,MT,MT3,and DMT1 m RNA expression in small intestine of broilers.Compared with Zn SO₄group,Zn-MMT significantly increased MT3 m RNA expression in small intestine and MT m RNA expression in duodenum and ileum.Meanwhile,Zn-MMT not only significantly increased Zn T-1and Zn T-2 m RNA expression in duodenum,but also increased DMT1 m RNA expression in jejunum and Zn T-2 m RNA expression in ileum of broilers（P<0.05）.However,the Zn T-2 m RNA expression in jejunum and Zn T-1,Zn T-5,DMT1 and MTF1 m RNA expression in ileum were decreased（P<0.05）.2)Compared with CK group,Zn-MMT not only significantly increased duodenal occludin,but also increased Claudin-5,ZO,Mucin-2,Occludin m RNA expression in jejunum and simultaneously increased Mucin-2,IL-10 m RNA expression in ileum（P<0.05）.However,Zn-MTT decreased of Claudin-2 m RNA expression in duodenum and ileum（P<0.05）.3)Compared with CK group,Zn-MMT not only significantly increased B⁰AT,Pep T1,and FATP4 m RNA expressions in small intestine of broilers,At the same time,it significantly increased GLUT5 and GLUT2 in duodenum and ileum（P<0.05）.Meanwhile,Zn-MMT increased EAAT3 in duodenum and SGLT1m RNA expressions in jejunum（P<0.05）,and significantly decreased EAAT3 m RNA expression in jejunum（P<0.05）.Compared with Zn SO₄group,Zn-MMT decreased of CAT1 m RNA expression and increased B⁰AT m RNA expression in small intestine of broilers（P<0.05）.Meanwhile,Zn-MMT not only significantly increased Pep T1,EAAT3,GLUT5 and GLUT2 m RNA expression in duodenum,but also increased FATP4,SGLT1 m RNA expression in jejunum and GLUT2 m RNA expression in ileum（P<0.05）.While it decreased EAAT3,Pep T1 and SGLT1 m RNA expression in ileum,and SGLT1 m RNA expression in duodenum（P<0.05）.Based on those results,it can be concluded as follows:（1）Supplementation with 40 mg/kg Zn-MMT could increase feed conversion rate,immune organ index,and promote intestinal villus development.（2）Supplementation with 40 mg/kg Zn-MMT could promote the deposition of trace elements in the organization,enhance of zinc-containing enzymes activity,improve the T-AOC and CuZnSOD activity of liver and jejunum,and reduce the MDA content,improve liver MT mRNA expression and improve the body’s antioxidant capacity（3）Supplementation with 40 mg/kg Zn-MMT could improve the expression of nutrient transporter in small intestine of broilers,promote the expression of tight junction protein,reduce intestinal permeability,and strengthen intestinal barrier.