RESUMEN
The study aimed to examine the effects of unfermented and fermented Andrographis paniculata on growth performance, carcass traits, immune function, and intestinal health in Muscovy ducks. A total of 450 (16-day-old) Muscovy ducks weighing 271.44 ± 8.25 g were randomly assigned to 5 dietary treatments (6 replicate pens of 15 ducks per treatment), consisting of one control treatment (basal diet without A. paniculata), one unfermented A. paniculata treatment (basal diet plus 30 g/kg unfermented A. paniculata) and 3 fermented A. paniculata treatments (basal diet plus 10, 30, and 50 g/kg). 30 g/kg unfermented A. paniculata increased the ADG, thymus index, peripheral blood lymphocyte conversion rate, villi height, intestinal thickness, villi surface area, intraepithelial lymphocytes rate, while decreased the FCR. 10 g/kg fermented A. paniculata markedly boosted ADG, bursa of fabricius index, thymus index, serum lysozyme, lymphocyte conversion rate, villi height, vilii width, intestinal thickness, villi surface area, while decreased the FCR. 30 g/kg fermented A. paniculata clearly improved ADG, bursa of fabricius index, thymus index, serum lysozyme, lymphocyte conversion rate, villi height, vilii width, intestinal thickness, villi surface area, intraepithelial lymphocytes, while decreased FCR. 50 g/kg fermented A. paniculata significantly increased villi height, vilii width, and villi surface area, while clearly reduced BW. Additionally, compared to 30 g/kg unfermented A. paniculata, 30 g/kg fermented A. paniculata obviously increased bursa of fabricius indices, lymphocyte conversion rate, vilii width, villi surface area. On top of that, supplementation with unfermented and fermented A. paniculata (30 g/kg each) decreased the relative abundance of harmful bacteria (Succinivibrio, Succinatimonas, Sphaerochaeta, and Mucispirillum) and increase the abundance of beneficial bacteria (Rikenellaceae, Methanocorpusculum, Fournierella, Ruminococcaceae) in the ceca of the ducks. However, fermented A. paniculata had considerable better effects than unfermented A. paniculate on all above measured indices. Overall, these results revealed that supplementation with unfermented and fermented A. paniculata across different treatments improved growth, immune status, intestinal morphology, and intestinal microbiota composition and structure in Muscovy ducks, making it a potential alternative to antibiotics in poultry production.