The impacts of fermented feed on laying performance, egg quality, immune function, intestinal morphology and microbiota of laying hens in the late laying cycle

•The effects of fermented feed on the hens in the late laying cycle were studied.•Fermented feed enhanced the laying rate, egg quality and reduced broken egg rate.•Fermented feed improved the immune functionality and intestinal integrity.•The gut flora was changed by increasing Lactobacillus and decreasing Campylobacter.•Fermented feed is an ideal functional feed to improve gut health for poultry. Fermented feed has the potential to improve poultry gastrointestinal microecological environment, health condition and production performance. Thus, the present study was undertaken to explore the effects of fermented feed on the laying performance, egg quality, immune function, intestinal morphology and microbiota of laying hens in the late laying cycle. A total of 360 healthy Hy-Line Brown laying hens aged 80 weeks were used to conduct a 56-day study. All hens were randomly separated into two treatment groups, with five replicates of 36 hens each as follows: basal diet containing 0.0% fermented feed (CON) and 20% fermented feed (FF). Subsequent analyses revealed that fermented feed supplementation was associated with significant increases in laying rates together with reduced broken egg rates and feed conversion ratio for hens in FF group (P