Proposed bursa of Fabricius weight to body weight ratio standard in commercial broilers.

Several causes may induce change and atrophy in the bursa of Fabricius (BF). Databases on BF standards are available from published studies, however, updated references are needed to adjust the BF standards to present changes in highly specialized broiler genetic lines. The aim of this study was to evaluate BF-related measurements (weight and dimensions) under controlled conditions that would mimic field situations. Chickens were kept in isolation, thus avoiding exposure to disease agents by vaccination or field infections. This study was conducted using male Cobb 500 commercial broilers from the same hatch and source. Absence of disease was confirmed throughout the study. Despite the presence of individual variations, a minimum bursa-to-body weight ratio standard of 0.11 is proposed in broilers from 7 to 42 days of age.