Infectious Bursal Disease has become the major poultry disease in Pakistan. The
disease causes immune suppression due to damage to primary lymphoid organs (Bursa of
Fabricius) in affected birds. Supplementation of fish oil enhances the immune status and subside
the inflammatory conditions. So this study was designed to study the effects of fish oil on
histopathology of lymphoid organs and growth performance of broiler birds. For this purpose a
total number of 80 day old Hubbard broiler chicks were randomly divided into four group i.e. A,
B, C and D. Group A and B were challenged with IBD Virus with known (EID50 106/ml) dose
was 0.1 ml intranasal on 21th day of age, Group B and C were treated with 3% fish oil while
group D acted as a negative control. Blood was collected from birds on irregular interval of days
20, 22, 29, 36 and 42 for monitoring of antibody titer against IBD virus and ND vaccine.
For the histopathology the lymphoid organ were collected on day 20, 22, 29, 36 and
42. Feed consumption of group A and D during 1st week of age was significantly higher than
group B and C. The broilers of group A consumed feed without fish oil significantly higher than
broiler of group D while, the broilers of group C consumed feed containing fish oil significantly
higher from the broilers of group D after challenged with IBD. The body weight of birds of
group B and C supplemented with fish oil mixed feed was significantly (p<0.05) higher than
broilers receiving feed without fish oil before challenged, however after challenge the body
weight gain of group C was significantly higher than group B while that of group D was
significantly (p<0.05) higher group A. The feed conversion ratio (FCR) of birds supplemented
with fish oil was significantly different from the broilers receiving feed without fish oil before
challenged.
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However after challenged significant difference was observed with highest value of
FCR by group C, followed by group B, group A and group D. Before challenged, group C show
the highest Mean titer value (606.0) for IBDV followed by group B (466.0), C (288.0) and D
(106.5), However, after challenge the highest value of Mean titer for IBDV was observed in
group B with 5006.0, followed by group C, A and D with Mean titer of 4608.0, 4469.0, and
4015.0, respectively on 42nd day of age.
During Histopathological examination, congestion, depletion of lymphocytes, dysplasia
of thymic lobules, thinning of cortex, focal necrosis, disappearance of lymph follicles and
interfollicular edema like lesions were observed in the lymphoid organs of challenged birds.
However, cellular hypertrophy, increased lymphocytes population and presence of lymphoblast
were the prominent changes in lymphoid organs of broilers supplemented with 3% fish oil, while
no pathological lesions were notified in the lymphoid organs of control group. From this study, it
was concluded that Infectious Bursal Disease causes immune suppression and damage immune
organs in broiler, with an associated loss of response to Newcastle disease vaccine.
It was also concluded from the current study that, fish oil had beneficial effect on the
antibody titer against Infectious Bursal disease virus and on growth performance in broilers. The
fish oil also showed therapeutic effect against Infectious Bursal Disease.