ABSTRACT A study was carried out to evaluate the impact of dietary onion powder (OP) on growth performance, serum biochemistry, gut morphology, and immune response in broiler chickens. A total of 320 day-old chicks each with a uniform initial body weight of 42.50 ± 0.40 g were raised in an open-sided shed for six weeks using a completely randomized design. Birds were weighed and randomly divided into four treatment groups. Each group was replicated five times with 16 chicks each. The dietary treatments included: T₁ (basal diet), T₂ (OP at 3 g/kg feed), T 3 (OP at 3.5 g/kg feed), and T 4 (OP at 4 g/kg feed). Growth performance parameters, serum biochemical indices, intestinal histomorphology, and immune response traits were evaluated across all groups. Results demonstrated that OP supplementation significantly ( P = 0.0001) improved growth performance. Cumulative feed intake and body weight gain increased in a dose-dependent manner, with the highest values recorded in the highest supplementation group (T 4 ). Feed conversion ratio was also significantly improved, while mortality remained unaffected across all treatments ( P = 0.640). Intestinal histomorphology was markedly enhanced, as OP increased villus height and villus height-to-crypt depth ratio, while reducing crypt depth, with the most pronounced effects observed in T 4 . Hematological indices, including red blood cells, white blood cells, hemoglobin, and packed cell volume, remained statistically unchanged ( P > 0.05). Serum biochemical analysis revealed significant improvements ( P < 0.05) in lipid and metabolic profiles, with reductions in cholesterol, triglycerides, glucose, and low-density lipoprotein, alongside increased high-density lipoprotein levels in OP-supplemented groups, particularly at higher OP-supplemented groups. Furthermore, humoral immune responses were significantly enhanced, with higher antibody titers against Newcastle Disease and Infectious Bronchitis. Dietary supplementation of onion powder, particularly at higher inclusion levels, effectively enhances growth performance, intestinal health, metabolic profile, and immune competence in broiler chickens without adversely affecting hematological stability. These findings suggest that onion powder can serve as a natural growth-promoting and health-enhancing feed additive in poultry production systems.
Zhong et al. (Mon,) studied this question.