This experiment was carried out to investigate the effect of dietary supplementation of
Chinese propolis on the histological structure of bursa of Fabricius in Ross 308 broiler
chickens. Eighty chicks were divided into 5 groups, 16 chicks each. Group 1 was fed only
on basic diet and kept as control while groups 2, 3, 4 and 5 were fed on basic diet and received
ether extract of propolis (EEP) in a dose of 100, 250, 500 or 750 mg/kg diet respectively.
The treatment started from the first day after hatching and extended to day 42 where
all birds were sacrificed and bursa of Fabricius were removed, processed and examined
histologically. Chickens received EEP in a dose of 100 and 250 mg/kg diet showed an increase
in size of the bursal folds and bursal lymphoid follicles with minimal regressive
changes into the bursa such as a slight increase in the amount of inter-follicular connective
tissue. Higher doses of EEP (500 and 750 mg/kg diet) produced substantial changes into
the bursa such as degeneration in lymphatic follicles represented by cyst formation,
liquifactive necrosis and significant increase in inter-follicular connective tissue. Our findings
suggest that high doses of EEP led to faster bursal involution with subsequent negative
impact on the humoral immune status of chicken.