Abstract
This study investigated the effects of graded levels of dietary silymarin (SM) supplementation at 0, 2, 4, 6, 8, 10 and 12 [g/kg] diet on growth performance, energy and nutrient availability, intestinal morphology, mucous cell populations and hepatic antioxidant status in unchallenged broiler chickens. Growth performance variables, including daily feed intake, weight gain and mortality‑corrected feed conversion ratio, were not influenced (p > 0.05) by SM inclusion. Although N-corrected apparent metabolisable energy, dry matter and nitrogen retention coefficients differed among treatments (p p > 0.05). No changes in breast meat colour were observed (p > 0.05). Jejunal villus morphometry and mucous cell types were largely unaffected by dietary treatments. Villus height and width did not vary among diets (p > 0.05), and although crypt depth, mucosal thickness and mucous cell subtype counts showed some treatment-specific differences (p p > 0.05). Compared to the control, hepatic coenzyme Q10 concentration increased in 12 [g/kg] SM (p p > 0.05). Overall, SM supplementation significantly affected some variables related to gut physiology, hepatic antioxidant status and energy and nutrient availability, although these effects were not consistently related to dietary SM inclusion level.