Newcastle Disease Vaccination using Mucoadhesive and Conventional Oral Delivery in Commercial Broilers: Serological, Heterophil: Lymphocyte ratio and Lymphoid Histopathological Changes

Newcastle Disease (ND) threatens poultry productivity worldwide. Vaccination remains central to control, but conventional oral delivery often yields short-lived immunity. Mucoadhesive systems are an alternative delivery method that improves mucosal antigen retention and immunogenicity. This study compared the serological, physiological, and immunoarchitectural responses of broiler chickens administered oral vaccination against ND with local or imported LaSota strains delivered either in water or via cashew gum-alginate microbeads. One hundred and five broiler chicks were assigned to six groups: unvaccinated controls, blank microbeads, imported LaSota in water (ILW) or microbeads (IML), and local LaSota in water (LLW) or microbeads (LML). Immune responses were assessed using hemagglutination inhibition (HI) assay, heterophil-to-lymphocyte (H:L) ratio, and histopathology of lymphoid tissues. The mucoadhesive local LaSota group (LML) produced the highest and most durable antibody titres (GMT ≥ 203.2, 14 and 35 days post-vaccination), significantly outperforming all others (P < .05). LLW peaked earlier but decayed rapidly, while imported vaccines (ILW, IML) showed weak responses. Histopathology revealed strong germinal centre formation in the spleen and jejunum of mucoadhesive groups. H:L ratios were significantly lower in these groups (P < .05), suggesting potent immunity without physiological stress. Growth performance was unaffected across treatments. Mucoadhesive microbeads enhanced ND vaccine efficacy by sustaining antibody production, improving lymphoid organization, and reducing stress. The superior response of the local strain emphasizes the importance of antigenic alignment with circulating variants. Results provide serological, histological, and welfare evidence for adopting mucoadhesive delivery as a practical strategy in ND control, particularly for backyard poultry.