Dry nettle (Urtica dioica) as a feed additive: impacts on duck growth, meat quality, gut morphology, gene expression, and microbiota

Abstract Background This study evaluated the effects of dried nettle ( Urtica dioica ) supplementation on broiler ducks. A total of 180 Cherry Valley ducks were assigned to three groups: control, 1% nettle, and 3% nettle. Growth performance, carcass traits, meat quality, intestinal morphology, digesta viscosity, liver gene expression, and cecal microbiota were assessed. During rearing, the ducks’ body weight, growth, feed intake, and conversion ratio were controlled and calculated. After slaughter, carcass composition, meat quality, duodenum and jejunum morphology, liver gene expression, and intestinal microbiota composition were analyzed. Results Nettle supplementation did not influence body weight, feed intake, feed conversion ratio, European Broiler Index, carcass yield, organ weights, or meat quality parameters. However, notable improvements in intestinal structure were observed, especially in ducks receiving 3% nettle, which showed increased duodenal villus width and surface area, as well as higher jejunal villus height. Digesta viscosity was significantly reduced in the jejunum of the 3% nettle group. Gene expression analysis revealed significant upregulation of CYP7A1 in the 1% nettle group and ALB in the 3% group. Antioxidant-related genes ( SOD1 and SOD2 ) were significantly upregulated, and GPX2 downregulated, only in the 3% nettle group, with no significant changes observed in the 1% group. Although beneficial bacterial populations were unchanged, a marked reduction in Fusobacterium nucleatum was detected in the 3% group, indicating a selective antimicrobial effect. Conclusions Dried nettle at 3% improved gut morphology and antioxidant responses without affecting growth or meat quality, supporting its potential as a functional feed additive.