Impact of synbiotic on growth performance, histo-architectural modulation of lymphoid organ, hematology, blood biochemistry and humoral immune response in naked neck chicken

Synbiotics, which synergistically enhance the development and activity of beneficial bacteria in the gastrointestinal tract, play a crucial role in the growth and production of chickens. However, their effects on lymphoid organs and immunity in Naked Neck (NN) chickens are not well understood. This experiment aimed to investigate the effects of synbiotics on growth performance, histo-architecture of lymphoid organs, hematology, serum biochemistry, and immunity in NN chickens in Bangladesh. In a randomized controlled trial, 120 day-old Naked Neck chicks (60 males, 60 females) were randomly assigned to four different treatments (T₀M, T₀F, T₁M, T₁F), with six replications per treatment over an 84-day experimental trial. The control group received a commercial diet, while the treatment group was given a commercial diet supplemented with a synbiotic (Protexin®: 1 ml/L + Prebiotic Inulin-FOS: 2 g/L). Blood samples were collected on days 14, 28, 42, and 56 for hematobiochemical parameters and humoral immune response assessment, while immune organs were collected on 84th day for histomorphometric analyses. The growth performance revealed synbiotic treated group showed significantly higher weight gain with lowest FCR on T₁M. Similarly, synbiotic-treated chickens showed significantly (P < 0.05) higher weight and organosomatic indices of the bursa and thymus. Histomorphometric analysis revealed an increased aggregation of B and T lymphocytes, as well as a greater number of aggregated lymphoid nodules in the treated group. Synbiotic-treated chickens also exhibited increased RBC, WBC, mean corpuscular hemoglobin concentration (MCHC), and lymphocyte percentage, along with higher levels of high-density lipoprotein (HDL) and significantly (P < 0.01) lower cholesterol and triglyceride levels. Immunologically, synbiotic-treated NN chickens showed significantly higher antibody titers against Newcastle disease on days 42 and 56. Synbiotic supplementation positively impacted lymphoid organ histomorphometry, hematobiochemical parameters, and immune responses in NN chickens.