Abstract

Infectious bronchitis (IB) is a disease with significant economic impacts both on the costs of control strategies and on productive losses. Various vaccination protocols are applied, depending on homologous or heterologous protection against IB and finding the optimal balance between costs and benefits as a choice by a responsible veterinarian. The current case study aimed to demonstrate the efficacy of a heterologous vaccine combination against field IBV GI-22 (Variant 2) infection when vaccination quality was properly monitored. Two groups, each consisting of six flocks, were examined before and after improving the quality of IB vaccine application in the hatchery. These groups were vaccinated with H-120 and 1/96 vaccine strains for heterologous protection. The study involved field visits, necropsies, serology via ELISA, and oropharyngeal sampling for RT-PCR follow-up activities. Moreover, performance parameters including average body weight, feed conversion ratio, and 7 days plus total mortality were analyzed at the end of the production cycle at 40-45 days of age. Results indicated that the group with enhanced vaccination quality in the hatchery exhibited a significant decrease in IBV titers and an absence of IBV GI-22 field infection. Additionally, there was an improvement in performance data in terms of average body weight, FCR and total mortality. Hatchery vaccination proved to be more controllable and practical compared to traditional on-farm vaccination, ensuring better control of the vaccination process and massive coverage of the farm population. © The Author(s) 2024