Bursa body index as a visual indicator for the assessment of bursa of Fabricius

The objective of the present study was to identify the significance of the Bursal-Body index (BB index) as a tool in assessing the health status of a chicken flock especially those under experimental condition. With the unending debate on the bursa of Fabricius as a diagnostic tool, a total of 135 day-of-hatch Dominant black Cockerel hybrid were housed in six separate houses with positive pressure and filtered airflow. Houses were assigned to the three vaccines (two intermediate (A, and C), and one intermediate plus (B) vaccine strain), a challenge group (D) and control group (E). The birds were vaccinated according to manufacturer’s directives on day 17th post hatch; challenge group was inoculated with 0.05 ml of very-virulent isolate of the infectious bursal disease virus (vvIBDV) on the same day. On day(s) 1, 2, 3, 4, 5, 7, 10, 14 and 21 post vaccination/challenge (Dpv/c) three birds were humanely sacrificed from each group with Bursal-Body ratio (BB ratio) and Bursal-Body index (BB index) recorded. The values (>0.7, that is, no atrophy (mild vaccine); 0.3-0.7 (relative or transient atrophy (for intermediate or intermediate plus vaccine) and 0.05) observed between the groups. This indicating that BB index could be used as a tool in assessing the health status of a flock. Key words: Avian, Bursa of Fabricius, bursal-body index (BB index), infectious bursal disease (IBD).