PATHOLOGICAL, HAEMATOLOGICAL AND BIOCHEMICAL CHANGES IN COCKERELS EXPERIMENTALLY INFECTED AND VACCINATED AGAINST INFECTIOUS BURSAL DISEASE VIRUS.
PATHOLOGICAL, HAEMATOLOGICAL AND BIOCHEMICAL CHANGES IN COCKERELS EXPERIMENTALLY INFECTED AND VACCINATED AGAINST INFECTIOUS BURSAL DISEASE VIRUS.
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Date
2014-08
Authors
KASSIM, IBRAHIM.
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Abstract
This study was conducted to determine pathological, haematological, and biochemical
changes in cockerels experimentally challenged with very virulent infectious bursal
disease virus (vvIBDV), and those vaccinated against Gumboro disease. Two hundred
and fifty day-old cockerels (chicks) were randomly distributed into 5 groups (A, B, C, D
and E) of 50 chicks per group. Group A chicks were vaccinated at 2 and 4 weeks of age
with intermediate strain (Georgia) IBD vaccine orally at dose of 10 ml (equivalent of 103
plague-forming units) per bird. Each bird in groups B, C and D was inoculated with 0.4
ml of vvIBDV inoculum equivalent to 16 x10 4.6 ELD50 of undiluted viral suspension via
conjunctival instillation at 4, 6 and 8 weeks, respectively. Group E served as the control
group. Chicks in this group were neither vaccinated against nor challenged with vvIBDV.
Blood samples were collected from birds in each group and analysed for haematological
parameters. Serum samples obtained from the birds were used to determine biochemical
parameters, and antibody titres to IBDV, using an enzyme linked immunosorbent assay
(ELISA) kit. Blood samples were collected one week after each vaccination in group A,
first and second week after challenge in groups B, C, and D, and weekly (week 1 – 10)
in the control group (E). Clinical signs exhibited by birds in the challenged groups
include whitish-yellowish mucoid diarrhoea, recumbency, prostration, drooped wings,
and reluctance to move. One hundred per cent morbidity rate was recorded in all the
challenged groups (B, C, and D), while mortality rates of 54%, 72% and 50% were
observed in groups B, C and D, respectively. The haematological parameters of the
challenged groups revealed significant decrease (p < 0.05) in packed cell volume (PCV),
total red blood cell count (TRBC) and haemoglobin concentration (Hb); and significantdecrease (p < 0.05) in lymphocyte and white blood cell count (WBC) values. On the
other hand, there was a significant increase (p < 0.05) in heterophil value. In the
vaccinated group, the haemogramme revealed significant decrease (p < 0.05) in
lymphocyte and heterophil values. There were significant decreases (p < 0.05) in total
protein (TP) and total cholesterol; as well as significant increase in urea (p < 0.05) in the
challenged groups. In the vaccinated group potassium and total protein were significantly
decreased (p < 0.05). Gross lesions, like enlarged, congested, haemorhagic and turgid
bursa of Fabricius; enlarged and congested kidneys; and haemorhages in mucosae of the
proventriculus were observed in the challenged groups. In the vaccinated group, no
clinical signs were exhibited, but mild gross lesions were seen. Histopathological changes
in the challenged groups revealed haemorhages, congestion, and necrosis of bursa of
Fabricius, liver, kidney, spleen and muscle. In conclusion, the study revealed some
pathological, haematological and biochemical differences in cockerels challenged with
vvIBDV, and those vaccinated against IBDV.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF
DEGREE OF MASTER OF SCIENCE IN VETERINARY PATHOLOGY.
Keywords
PATHOLOGICAL,, HAEMATOLOGICAL,, BIOCHEMICAL CHANGES., COCKERELS EXPERIMENTALLY,, INFECTED AND VACCINATED,, AGAINST,, INFECTIOUS BURSAL,, DISEASE VIRUS.