Regulation Of Oregano Aqueous Extract On Performance And Intestinal Mucosal Immunity Of Broilers

In recent years,people’s demand for poultry products is increasing.In intensive livestock and poultry farming,various stressors seriously affect the health of the body.Intestinal health is the most important factor affecting broiler performance.A complete intestinal barrier maintains intestinal health and body health by preventing tissue damage,pathogen infection and disease development.Oregano is a perennial herb,also known as dysentery herb.Its plant extract contains more than 50 kinds of compounds,the main chemical components are phenols,terpenes and their derivatives,fatty acids,flavonoids,sterols,etc.Oregano extract is widely used in livestock and poultry production because of its anti-inflammatory,antibacterial and immunomodulatory effects.However,the effects of oregano aqueous extract(OAE)on intestinal health of broilers and its mechanism are still unclear.This study aimed to investigate the potential effects of OAE on growth performance,gut microbiota and intestinal health,then verify the role played by microbiota in affecting intestinal health.Experiment 1 Effects of oregano aqueous extract on growth performance and intestinal health of BroilersA total of 840 1-day-old healthy AA broilers were randomly assigned to 6 treatment groups(Con group,Anti group and 400,500,600,700 mg/kg OAE supplemental groups)to explore the effects of OAE on growth performance and intestinal health.The results showed as follows: 1)Dietary OAE addition could enhance(P < 0.05)the body weight,average daily gain and feed conversion rate of broilers at D42,and 700 mg/kg supplemental level had the best effect.2)Except for 600 mg/kg OAE supplemental group,dietary OAE supplementation decreased(P < 0.05)crypt depth in jejunum of broilers at D42.3)Except for 500 mg/kg OAE supplemental group,dietary supplementation of OAE down-regulated(P < 0.05)the expression of MUC2 in jejunum at D42,dietary supplementation of OAE also significantly decreased(P < 0.05)the expression of IL-4 and IL-10 in jejunum as well as IL-10 in ileum at D42,and increased(P < 0.05)the secretion of SIg A in jejunum.4)OAE could enrich Lactobacillus and increase the content of acetic acid in chyme(P < 0.05).The results of this experiment showed that OAE could improve the growth performance and intestinal health,and the optimal supplemental amount was 700 mg/kg,adding OAE to the diet for 42 days is more effective in improving the performance of broilers.Experiment 2 Direct effects of oregano aqueous extract on microbiota and SCFAs in vitroTwo treatment groups were set up in this experiment,which was without(Con)and with(Treat)oregano aqueous extract in vitro fermentation.Samples were collected at 12,24 and48 h to detect microbiota and SCFAs.The results showed that: 1)compared with the Con group,the Alpha diversity of Treat group was significantly increased(P < 0.05)at 24 h of fermentation.At each time period,the microbial community structure of Treat group and Con group was significantly different(P < 0.05),and the composition of microorganisms within the groups was relatively similar.2)The abundance of Lactobacillus in Treat group was significantly higher(P < 0.05)than that in Con group at each time period,while the abundance of Unspecified＿Enterobacteriaceae in Treat group decreased(P < 0.05)with the increase of fermentation time,and was significantly lower(P < 0.05)than that in Con group.Acetic acid concentration in Treat group was significantly higher(P < 0.01)than that in control group.The results of this experiment showed that OAE could inhibit the propagation of harmful bacteria in vitro,promote the growth of beneficial bacteria,and change the content of SCFAs as well as the p H of fermentation broth,which was consistent with the experimental results in vivo.Experiment 3 Mechanism of oregano aqueous extract improving intestinal mucosal immunityA total of 90 1-day-old healthy AA broilers were randomly assigned to 3 treatment group(C,S and M).To investigate whether OAE regulated intestinal mucosal immune through gut microbiota,we gavaged oregano fermentation supernatant or microbe to verify the role of microbe in regulating intestinal health.The results showed as follows: 1)The relative m RNA expression of IL-4 was significantly increased in M group in the jejunum and ileum at D42.2)At D42,the m RNA expression of MUC2 in the ileum showed an upward trend in S group(P= 0.069).In addition,gavage of supernatant increased the secretion of SIg A in the ileum(P =0.073).The results of this experiment showed that the expression of IL-4 and IL-10 may be regulated by microbiota,SIg A and MUC2 may be affected by SCFAs.Intestinal microbiota and SCFAs act synergistically to protect intestinal homeostasis.In conclusion,this study demonstrated that OAE could promote the growth of Lactobacillus,and inhibit the growth of harmful bacteria,thus improving mucosal immunity.While the special microbiota could drive the production of acetic acid,which could enhance the protection of mucin and SIg A in the intestine.The healthy gut environment was improved by Lactobacillus and acetic acid,which was important for improving growth performance.