Effect Of EGCG On Intestinal Structure And Antioxidant Properties Of Heat-stressed Broilers

In recent years,with the large-scale development of poultry farming and the impact of global warming,heat stress occurs frequently in poultry farming,causing huge losses to the poultry breeding industry and is not conducive to the development of poultry farming.Heat stress can trigger oxidative stress and inflammatory response in poultry,which can damage the structure and function of the intestinal barrier of poultry,thereby destroying the balance of intestinal flora,changing the permeability of intestinal epithelial cells,causing bacteria and endotoxin.Into the internal environment of poultry,causing inflammation and peroxidative damage,in addition,heat stress will reduce the immunity of the intestines of poultry and increase the incidence of disease.Damage to the intestines of poultry directly affects the intake and utilization of feed intake and nutrients,reduces the production performance of poultry,and affects the economic benefits of poultry farming.In this study,AA broiler was used as the research object to carry out heat stress treatment.The purpose of this study was to investigate the intestinal mucosal morphology,barrier function,proinflammatory cytokine expression and antioxidant capacity of galangose gallate(EGCG)on heat-stressed broilers.The impact of EGCG on the use of EGCG in the prevention and mitigation of heat stress damage in poultry provides a theoretical basis.A total of 192 2?week?old Arbour Acres broilers chickens were divided into four groups with six replicates per group and eight chickens per replicate: one thermoneutral control group(28°C,group TN),which was fed the basal diet;and three cyclic high?temperature groups(35°C from 7:00 to 19:00 hr;28°C from 19:00 hr to 7:00 hr,heat stress group),which were fed the basal diet supplementation with EGCG 0 mg/kg(group HS0),300 mg/kg(group HS300)and 600 mg/kg(group HS600).At the 21,28 and 35 days of broiler broil,1 chicken in each of the 4 test groups was randomly selected for sacrifice.The autopsied anatomical instrument was used to dissect and collect the entire mucosal jejunal sample,which was washed with pre-cooled 2% cyanine-streptomycincontaining DPBS solution for intestinal morphology determination,and the additional jejunal sample was quickly removed.It was placed in liquid nitrogen for rapid freezing,and then the frozen jejunal sample was placed in a-80°C ultra-low temperature refrigerator for analysis of the later antioxidant index.Three 35-day-old samples were selected for each group for mRNA expression analysis.The gut morphology and intestinal mucosal oxidative stress indicators,as well as intestinal barrier?related gene expression,were analysed.The results showed that compared with group TN,heat stress reduced the villus height(VH),activities of glutathione peroxidase(GSH?Px),superoxide dismutase(SOD)and catalase(CAT),increased the crypt depth(CD)and malondialdehyde(MDA)content at 21,28 and 35 days(p < 0.05).After the heat?stressed broilers were supplemented with EGCG,VH,VH/CD(V/C),and the activities of GSH?Px,SOD and CAT were increased,and CD and MDA content were reduced compared with those in group HS0 without EGCG supplementation at 21,28 and 35 days(p < 0.05).The EGCG supplementation promoted the gene expression of nuclear factor?erythroid 2?related factor 2(Nrf2),Claudin?1,Mucin 2(Muc2)and alleviated the nuclear factor?kappa B(NF??B)and lipopolysaccharide?induced tumour necrosis factor(LITAF)gene expression compared with group HS0(p < 0.05).Moreover,intestinal morphology was strongly correlated with antioxidant ability and inflammatory response.In conclusion,EGCG alleviated the gut oxidative injury of heat?stressed broilers by enhancing antioxidant capacity and inhibiting inflammatory response.Heat stress significantly reduced the antioxidant capacity of the intestinal mucosa and up-regulated the expression of inflammatory cytokines,which adversely affected jejunal morphology.The addition of ECGC to the diet can effectively improve the antioxidant capacity and anti-inflammatory ability,and improve the intestinal morphological damage caused by heat stress.