Abstract
Background Global warming leading to heat stress(HS)is becoming a major challenge for broiler production.This study aimed to explore the protective effects of seaweed(Enteromorpha prolifera)polysaccharides(EPS)on the intesti-nal barrier function,microbial ecology,and performance of broilers under HS.A total of 144 yellow-feathered broilers(male,56 days old)with 682.59±7.38 g were randomly assigned to 3 groups:1)TN(thermal neutral zone,23.6±1.8 ℃),2)HS(heat stress,33.2±1.5 ℃ for 10 h/d),and 3)HSE(HS+0.1％EPS).Each group contained 6 replicates with 8 broilers per replicate.The study was conducted for 4 weeks;feed intake and body weights were measured at the end of weeks 2 and 4.At the end of the feeding trial,small intestine samples were collected for histomorphology,anti-oxidant,secretory immunoglobulin A(slgA)content,apoptosis,gene and protein expression analysis;cecal contents were also collected for microbiota analysis based on 16S rDNA sequencing.Results Dietary EPS promoted the average daily gain(ADG)of broilers during 3-4 weeks of HS(P＜0.05).At the end of HS on broilers,the activity of total superoxide dismutase(T-SOD),glutathione S-transferase(GST),and the content of slgA in jejunum were improved by EPS supplementation(P＜0.05).Besides,dietary EPS reduced the epithelial cell apoptosis of jejunum and ileum in heat-stressed broilers(P＜0.05).Addition of EPS in HS group broilers'diet upregu-lated the relative mRNA expression of Occludin,ZO-1,γ-GCLc and IL-10 of the jejunum(P＜0.05),whereas down regu-lated the relative mRNA expression of NF-κB p65,TNF-α and IL-1β of the jejunum(P＜0.05).Dietary EPS increased the protein expression of Occludin and ZO-1,whereas it reduced the protein expression of NF-κB p65 and MLCK(P＜0.01)and tended to decrease the protein expression of TNF-α(P=0.094)in heat-stressed broilers.Furthermore,the proportions of Bacteroides and Oscillospira among the three groups were positively associated with jejunal apoptosis and pro-inflammatory cytokine expression(P＜0.05)and negatively correlated with jejunal Occludin level(P＜0.05).However,the proportions of Lactobacillus,Barnesiella,Subdoligranulum,Megasphaera,Collinsella,and Blautia among the three groups were positively related to ADG(P＜0.05).Conclusions EPS can be used as a feed additive in yellow-feathered broilers.It effectively improves growth perfor-mance and alleviates HS-induced intestinal injury by relieving inflammatory damage and improving the tight junction proteins expression.These beneficial effects may be related to inhibiting NF-κB/MLCK signaling pathway activation and regulation of cecal microbiota.
基金项目
National Nature Science Foundation of China(32002196)
维普
万方数据