Aim: A safety pharmacology
trial was conducted to evaluate the impact of enrofloxacin on zootechnical
performance, behaviour and immunohistopathological response in Newcastle disease
virus vaccinated broiler chicken after pulsed water medication.
Materials and
Methods: Experimental group birds were administered with enrofloxacin at
recommended therapeutic dose 10mg/Kg body weight, through drinking water for
five consecutive days from 43rd to 47th day of age. Zootechnical performance
parameters, behavioural and humoral immune response in terms of
haemagglutination inhibition (HI) titre were assessed at different time interval
during pre-treatment, treatment, post-treatment period. Bursa of Fabricius and
spleen tissues collected at each sampling point viz. 1, 3, 5, 7 and 9 days post
treatment were subjected to histopathological examination.
Results: A
significant reduction in HI titre was noticed in enrofloxacin administered
birds. The decreased HI titre was further substantiated by the histopathological
changes observed in bursa of Fabricius and spleen which showed a lymphocytic
dispersion and depletion with several areas of lymphoblastic degeneration.
Conversely, a down regulatory effect on humoral immunity was observed as
evidenced by increased HI titre value noticed from 5th day post treatment
onwards and a congruent reversible trend in histopathological changes as
indicated by repopulation with lymphocytes on 9th day post treatment. However,
there was no significant change in body weight, cumulative feed intake, feed
efficiency and behaviour in enrofloxacin administered groups.
Conclusion:
The present study suggests that the immuno suppressive activity of enrofloxacin
may alter the immune response to vaccines, if it is coadministered during
vaccination of broilers. On the other hand, enrofloxacin, though it decreased
the humoral immune response, it did not have any appreciable effect on broiler's
performance.
Keywords: broiler chicken, enrofloxacin,
immunohistopathology, safety pharmacology, zootechnical performance
