Effects Of Bacillus Subtilis And Chito-Oligosaccharides On Antioxidant,Immune And Intestinal Barrier Function In Broilers

This study was conducted to investigate the effects of Bacillus subtilis(BS)and Chitosan oligosaccharides(COS)on antioxidant,immune and intestinal barrier function of broilers.A total of 288 1-day-old broilers with similar body weight(30±0.64 g)were randomly divided into 6 treatment groups.The control group was fed a basal diet(CON group),while the experimental group was fed a basal diet+5×109 CFU/kg Bacillus subtilis(BS1 group),a basal diet+6×109 CFU/kg Bacillus subtilis(BS2 group),a basal diet+125mg/kg chito-oligosaccharides(COS group)and a basal diet+5×109,respectively CFU/kg Bacillus subtilis+125 mg/kg chito-oligosaccharides(MIX1 group),basic diet+6×109CFU/kg Bacillus subtilis+125 mg/kg chito-oligosaccharides(MIX2 group);There were 6replicates in each treatment and 8 chickens in each replicate.After 42 days of feeding,the serum,liver,bursa of Farsi,thymus,duodenum,jejunum,ileum and cecal chyme were collected and slaughtered.The immune organs were drained and weighed,and the remaining tissues were stored at 4℃,-20℃and-80℃as required.Experiment 1:Effects of Bacillus subtilis and chito-oligosaccharides on Growth Performance of broilers.Broilers were fed in two stages.Feed intake and body weight were recorded during feeding,and average daily gain,average daily feed intake and feed conversion rate were calculated.The results showed that BS,COS and their mixtures could increase the ADFI and body weight of broilers at 1-21 days of age,among which the ADFI and body weight of broilers in MIX1 group were increased by 4.5%and 4.3%,respectively,and the FCR of broilers in MIX2 group was significantly increased at 1-21 days of age.The FCR of MIX2 group at 1 to 42 days of age was significantly increased(P<0.05).Experiment 2:Effects of Bacillus subtilis and chito-oligosaccharides on antioxidant capacity of broilers.The effects of Bacillus subtilis and chito-oligosaccharides on antioxidant performance of broilers were analyzed by measuring antioxidant indexes in serum,liver and small intestine and relative m RNA expression levels of antioxidant-related genes.The results showed that BS and COS had no significant effect on the activities of serum antioxidant enzymes and T-AOC,but the activities of CAT,GSH,GPX and T-AOC in liver were increased,and the contents of MDA in serum,liver and ileum were decreased.The relative expressions of CAT,GPX,SOD,Nrf2 and HO-1 m RNA in liver and small intestine were up-regulated to varying degrees.Experiment 3:Effects of Bacillus subtilis and chito-oligosaccharides on Immune function of broilers.The effects of Bacillus subtilis and chito-oligosaccharides on immune function of broilers were analyzed by measuring immune organ index,immune index in serum,liver and small intestine,and relative m RNA expression levels of immune-related genes.The results showed that adding BS and COS could increase spleen index of broilers.The contents of IL-1βand IL-4 in serum and liver were increased,while the contents of TNF-αin serum were decreased.The contents of TNF-αin duodenum and jejunum were increased,while the contents of IL-1β,IL-2,IL-4,IL-6 and IL-10 in jejunum were increased.The contents of IL-1β,IL-4 and IL-6 in ileum decreased.The expression of TLR4 m RNA,IL-1βand IL-6 and NF-κB50,NF-κB65 and IL-10 in liver were up-regulated.The expression of TLR4 m RNA was not significantly down-regulated in small intestine,but significantly up-regulated in My D88,NF-κB50,NF-κB65 and IL-10(duodenum and jejunum)m RNA.Experiment 4:Effects of Bacillus subtilis and chito-oligosaccharides on intestinal barrier function in broilers.The effects of Bacillus subtilis and chito-oligosaccharides on intestinal barrier function of broilers were reflected by intestinal morphology,relative m RNA expression levels of intestinal barrier related genes and relative number of cecum flora.The results showed that the addition of BS and COS could increase ileum lint ratio and up-regulate m RNA expression of ZO-1,JAM-2,Occludin,ileum Occludin and MUC2 in duodenum.The relative number of beneficial bacteria Odoribacter and Oscillospira increased significantly,while the relative number of harmful bacteria Shuttleworthia decreased.In conclusion,Bacillus subtilis and chito-oligosaccharides can improve antioxidant capacity,regulate immune function and maintain intestinal barrier function of broilers,and the combination of the two has the same effect,and the best effect is 5×10~9 CFU/kg BS+125mg/kg COS.