EFFECTS OF DIETARY L-CARNITINE AND A BACILLUS-BASED PROBIOTIC ON GROWTH PERFORMANCE, PLASMA BIOCHEMICAL INDICES, AND DUODENAL HISTOLOGY OF ROSS 308 BROILERS

This study evaluated the effects of dietary L-carnitine and a Bacillus-based probiotic, administered individually or in combination, on growth performance, plasma biochemical and antioxidant indices, and duodenal histological features of Ross 308 broiler chickens. A total of 240 one-day-old Ross 308 chicks were randomly allocated to four dietary treatments (n = 60 per treatment; three replicates of 20 birds each). The control group (T1) received a basal diet without additives, whereas T2 was supplemented with 200 mg/kg L-carnitine, T3 with 1 g/kg probiotic, and T4 with a combination of 200 mg/kg L-carnitine and 1 g/kg probiotic. The experimental period lasted for 28 days. Broilers receiving the combined supplementation (T4) exhibited the highest final body weight (1650 g) compared with the control group (1536 g; P < 0.05). Dietary L-carnitine, alone or in combination with the probiotic, significantly reduced plasma cholesterol and triglyceride concentrations, indicating an improvement in lipid metabolism. Plasma malondialdehyde (MDA) concentrations were elevated in the probiotic-only group (T3), whereas superoxide dismutase (SOD) activity was reduced in all supplemented groups relative to the control. Total antioxidant capacity (TAOC) and plasma calcium levels were not significantly affected by dietary treatments, while total protein, albumin, and phosphorus concentrations were significantly increased in all supplemented groups. Qualitative histological examination of the duodenum revealed favorable villus architecture and goblet cell activity in supplemented birds, particularly in those receiving the combined treatment. Overall, these findings demonstrate that combined dietary supplementation with L-carnitine and a Bacillus-based probiotic enhances growth performance, improves lipid metabolism, modulates oxidative status, and promotes intestinal health, suggesting a synergistic nutritional strategy for broiler production under intensive rearing conditions.