COMPARATIVE HISTOMORPHOLOGICAL STUDY OF NON-AFFECTED AND AFFECTED LYMPHOID ORGANS BY NEWCASTLE DISEASE (ND) IN BROILER CHICKEN

Abstract

Newcastle disease (ND) remains a constant threat to the poultry industry and is a limiting disease for poultry producers worldwide. Newcastle disease (ND) has been considered as one of the important viral diseases. Poultry production is an easy and efficient way of producing animal protein. With less capital investment relatively more profit could be earned by producing poultry. About 31.5 percent people live under malnutrition (Brad Field, 2010). The average quantity of protein uptake by people is insufficient per head per day where as desirable requirement is decreasing daily per head day by day. At present there are more than about 30,000 commercial broiler and layer farms are supplying 260 thousand metric ton poultry meat and 5.21 billion table eggs per year (Rahman, 2003). The current investment in poultry sector is about 22 billion taka and a total of about 5 million people are working presently in this sector (Rahman, 2003). The poultry population of Bangladesh has increased from around 71 million in 1986 to around 188 million in 2006, an increase of about 164 percent in 20 years (FAO 2008, BBS 2006). Poultry can be an important tool to fight poverty not only for this group of people but also for the distressed women as poultry requires minimum land, short capital and skill. Despite the special emphasis of the state on this sector, the development of poultry industry is seriously threatened by the outbreaks of acute contagious and fatal diseases. Among them Newcastle diseases (ND), also known as Ranikhet diseases, is one of the major problems in the development of poultry industry in Bangladesh. It causes considerable economic losses to the poultry industry due to high mortality, morbidity, stress, decreased egg production and hatchability throughout the world (Alexander, 2000) including Bangladesh (Kafi et al., 2003). ND has been recognized as one of the major problems of the large and small poultry industries in Bangladesh (Islam et al., 1998; Rahman and Samad, 2003) and it causes up to 40-60% of total mortality among poultry population in Bangladesh (Talha et al., 2001). Mortality and morbidity is very high in this case. Occurrence of the disease is reportable and may result in trade restrictions. The purpose of this study was to observe the histomorphological and histopathological features of the major lymphoid organs of Newcastle Disease affected chicken in Dinajpur vi district of Bangladesh. The investigation carried out in different farms of mentioned area. The investigation was conducted from 1st July’14 to 30th June’15. On gross and microscopic examination of lymphoid organs like thymus, spleen, cecal tonsil and bursa fabricious that are collected freshly from different farms was subjected for Newcastle Disease condition and observed these lymphoid organs in chicken affected with Newcastle Disease. Organs were cleaned with normal neutral saline and the changes were recorded. A total of ten farms (5 days to 35 days old) has been selected where total number of birds were 5000. Birds were divided into ten groups, each group contained 300-700 birds; namely A (N= 400), B (N = 600), C (N-300), D (N-700), E (700), F (N-300), G (N-350), H (N-650), I (N-500), J (N-500). After gross and microscopic study I found that mortality was 1.52 times higher in the non-vaccinated birds due to NDV. Clinical signs were marked depression, prostration, droopy wings, muscle tremor, greenish white diarrhea, edema of the head, inactive, weak, accompanied by the nervous signs (torticollis) are major. Gross changes were occur like swollen and molted spleen, enlargement of cecal tonsil with hemorrhage, swollen and yellowish bursa, thymic enlargement etc. In the spleen Lymphocytes degeneration, necrosis, nuclear pyknosis etc. and hemorrhages, congestion in mucosa, necrosis etc in caecal tonsil has been observed. In Bursa of Fabricius lymphoid depletion, lymphocytolysis, marked interfollicular fibrosis, glandular transformation of epithelium occurred. Medullary lynphocytolysis in thymus are common histopathological changes has been observed in the thymus. Overall the performance of ND affected birds were remarkably reduced which is directly influenced the profitability of the farmers.