Horehound (Marrubium vulgare L.) as natural dietary feed additive in rabbit: effects on productive traits, antioxidant status, caecal environment, and gut morphology

Marrubium vulgare L., commonly known as horehound in Europe, belongs to theLamiaceae family, one of the most prominent medicinal plant families in theMediterranean region. Traditionally used in herbal medicine, horehound containsa broad spectrum of bioactive compounds, supporting its potential use as anatural feed additive in animal nutrition. This study evaluated the effects of dietaryhorehound powder (HP) on growth performance, serum antioxidant status,digestive enzyme activity, intestinal microbial populations, and gut and liverhistomorphology in growing rabbits. Eighty weaned male Bianca Italianarabbits (42 days old) were randomly assigned to two dietary groups for a 6-week feeding trial: a control group fed a basal diet and a treatment groupreceiving the same diet supplemented with 0.15% HP (1.5 g/kg). At slaughter (84days of age), samples of meat, blood, liver, and intestinal tissue were collected foranalysis. Dietary HP signi fi cantly improved fi nal body weight, feed conversionratio, and carcass yield (P < 0.01), with no notable differences in proximate meatcomposition. However, meat from HP-fed rabbits showed increased totalpolyunsaturated fatty acids (PUFAs) (P < 0.05) and n-6 fatty acids (P < 0.01).Serum lipid pro fi les remained unaffected, while serum antioxidant parameters —total antioxidant capacity (TAC), malondialdehyde (MDA), and superoxidedismutase (SOD )— were signi fi cantly enhanced in the HP group. Additionally,HP supplementation increased the activity of duodenal a -amylase, maltase,lipase, and trypsin (P < 0.05). Although caecal morphology did not differsigni fi cantly between groups, rabbits receiving HP exhibited higherLactobacillus spp. counts and reduced Escherichia coli populations. Duodenalhistomorphometry showed signi fi cant improvements in villus height, cryptdepth, and the villus height to crypt depth ratio (P < 0.01). No histological alterations were observed in the liver of rabbits. In conclusion, dietary inclusion ofhorehound powder positively in fl uenced growth performance, oxidative status,digestive enzyme activity, and intestinal health in rabbits, supporting its use as afunctional feed additive in sustainable rabbit production.