ABSTRACT

This study was conducted with the aim of determining the effect of multiple infectious bursal disease vaccination on antibody response of pullets to Newcastle disease (ND) vaccine LaSota and pathological changes on major immune organs. A total of 120 day-old pullets were used, the birds were randomly divided into 6 groups (A, B, C, D, E and F), consisting of 20 chicks each. A freeze-dried live attenuated infectious bursal (IBD) disease vaccines, M.B. strain (ABIC) and Newcastle disease vaccine LaSota strain live virus (ABIC) were administered orally. Group A pullets were vaccinated with IBD vaccine at 1st and 2nd weeks of age. Group B pullets received IBD vaccine at 2nd and 4th weeks. Group C pullets received IBD vaccine at 3rd weeks. Group D pullets received IBD vaccine at 2nd, 4th and 6th weeks. All the groups with the exception of group F received ND vaccine at 3rd and 6th weeks. Group F pullets received no vaccine. Ten serum samples from each group in this experiment were collected for 8 weeks and tested against ND for antibodies using ELISA test. Mean Elisa ND antibody titre had indicated statistical difference at week 5, where groups B and A (P≤0.01), C and B (P≤0.01) and D and C (P≤0.05). At week 7 groups D and C (P≤0.01). The multiple IBD vaccine had negative effect on ND vaccine LaSota, group C had highest ND mean Ab titre of 11480.6 ±827.45 at week 8. The gross lesions observed were more severe in groups B and D and milder in group E and F. Histopathologically lesions were more severe in groups that where vaccinated with multiple IBD vaccines. From this work it was recommended that it is safer to give two weeks interval before repeating infectious bursal disease vaccination for Newcastle disease vaccine LaSota vaccination to be effective.

CHAPTER ONE

1.0 Introduction

1.1 Historical Background

Poultry diseases are significant restrain to the efficiency and profitability of poultry production. From a global perspective basically the same range of poultry pathogens are responsible for losses in livability, egg production, growth rate and feed efficiency worldwide (Shane, 2004). In many developing countries, velogenic Newcastle disease (ND) is endemic, and represents an important limiting factor in the development of commercial poultry production and the establishment of trade links (Alexander et al., 1997). The constant loses from ND severely affect the quality and quantity of food for people on marginal diets (Saif et al., 2005). The endemicity of ND in Nigeria leads to high environmental dissemination of the virus and this is enhanced by poor husbandry practice (Okwor and Eze, 2010). The outbreaks of ND were reported to be more common in layers than in broilers (Abdu et al., 2005).

1.2 Statement of research problem

In Nigeria, poultry contributes about 15% of the total annual protein intake with approximately 1.3 kg of poultry products consumed per head per annum (Ologbon and Ambali, 2012). However, major factors militating against the growth of the poultry industry include infectious diseases especially infectious bursal disease (IBD) and ND. Farmers administer ND and IBD vaccines simultaneously with the aim to reduce stress and minimize labour cost (Okwor et al., 2013). In Nigeria, farmers vaccinate birds against IBD and ND at regular intervals depending on the vaccination scheduled, some vaccinate against IBD once, twice and thrice (Okwor et al., 2013). Vaccination using live IBD vaccine has been reported to affect response of birds to vaccination against other disease like ND (Ali et al., 2004). However, some viruses like IBD virus are immunosuppressive in nature and may interfere with chicken’s immune responses to other viral vaccines which may be responsible for vaccination failure (Hair-Bejo et al., 2004). The use of live vaccines can result in negative vaccination reactions, especially if the birds are stressed (Alexander, 2004). Infectious bursal disease has been reported to be immunosuppressive and even the attenuated vaccines are reported to cause pathology in the bursa of Fabricius (Adamu et al., 2013). Several IBD vaccination failures have been reported in Nigeria (Abdu, 1986). The endemic nature of Newcastle disease in Nigeria ensures the ND virus is almost always present in poultry populations particularly village chickens and backyard flocks (Abdu, 1997). The village poultry flocks suffer from outbreaks of ND annually and these flocks are also in constant contact with backyard flocks. Vaccine failures in Nigeria were reported to occur primarily due to improper storage, transportation and administration of vaccine and secondarily due to interference with active immunization by Marternally derived antibody (Abdu, 1997). Research efforts on IBD control by conventional immunization or strict management practice is wroth with frustration.

1.3 Justification of the Study

Newcastle disease and infectious bursal disease have remained the two most important viral infectious diseases that are threatening commercial poultry production in most parts of the world (Agoha et al., 1992; Sonaiya et al., 1999; Permin and Pederson, 2002). The epidemiology of these two diseases involves host’s immune status, wide host range, thermo-stability and antigenic variations in strains of the causative viruses (El-Yuguda et al., 2014). Unfortunately, severe outbreaks of ND still occur with high mortality rates in vaccinated and unvaccinated flocks (Musa et al., 2010). Economic losses of IBD are incurred as a result of the high mortality rate and the predisposition to secondary infection (Adewuyi et al., 1989). Field IBDV reports by different researchers indicated varying level of maternally derived antibody (MDA) in birds (Giambrone, 1983). Neutralization of IBDV by MDA at the time of vaccination was also reported (Okoye, 1984; Abdu, 1997). Immunosuppression caused by IBD has a significant economic impact due to widespread nature of the virus in chicken (Abdu, 1997). The infection at an early age compromise the humoral and the cellular immune response of chicken (Abdu, 1997). It has been observed, that ND outbreak occur more commonly in flocks recovered from IBD (Adewuyi et al., 1989). Therefore, this work was designed to find out whether IBD vaccination will have an effect on the antibody response to Newcastle disease vaccine (LaSota) strain.

1.4 Aim

The aim of the research was to study the effects of multiple IBD vaccinations on antibody response of pullets to ND vaccine LaSota and pathological changes on major immune organs.

1.5 Objectives of the Study
Were to;

1. Determine the antibody response of pullets to Newcastle disease LaSota vaccine following multiple IBD vaccine application in pullets.
2. Observe the gross and histopathological changes of some immune organs of pullets after IBD vaccination.

1.6 Research Questions

1. Does IBD vaccination affect antibody response of pullets to ND LaSota vaccine?
2. Does IBD vaccination cause pathological changes in major immune organs of pullets?