Lesion Scores of Bursa Cloacae in Broiler
Evaluation of Size and Lesion Scores of Bursa Cloacae in Broiler Flocks in Algeria
Published: June 28, 2012
By: S. Sellaoui, Nadir Alloui, S. Mehenaoui (University of Batna, Algeria)and S. Djaaba (Anatomopathologic Laboratory, CHU, Batna, Algeria)
INTRODUCTION
The outbreaks of IBD (infectious bursal disease) are frequently observed among correctly vaccinated broiler flocks in Algerian Nord-East region. The present study aimed to search for the immunosuppression state as possible consequence of IBD.
Thebursa of Fabriciusis an immunological organ that plays a primordial role in the poultry immunity (Toivanen et al., 1987; Awad,2002). It is according to its physiological state that will especially depend on the immune status of poultries at the beginning of broiler chickens weight development. The different aggressions of the environment (stress, bad hygiene, vaccination, pathologies…) undergone by birds, influential on the anatomical and physiological development of the bursa of Fabricius. It can, therefore, lead to an immunosuppression at certain birds. The use of vaccines calledvirulent "warm" can sometimes compromise immunity at poultries while causing some lesions of this organ (OIE, 2001; van den Berg et al., 2000). The consecutive immunosuppression to lesions of this vital organ provokes very often negative vaccinal reactions and some complications in poultry flocks: bad absorption, secondary infection, weak gain of weight and finally diverse diseases. In this survey, we valued morphometrical and histological evolution of the broiler cloacal bursa in the natural conditions.
MATERIAL AND METHODS
The investigation is done on nine flock poultry of 3000 broilers each, elevated in open broiler houses and vaccinated against the infectious bursal disease (IBD) with a vaccine "Intermediate plus". Morphometrical survey of the bursa of Fabricius has been done thanks to the method of Kuney (1982). Broilers are weighed then sacrificed during raising. The autopsy is achieved on broiler chickens presenting no clinical sign of disease. The bursa ofFabricius are taken, examined, weighed and measured with the help of a "bursameter"(Figure 1).
Figure 1. Bursameter (Solvay animal health, 1992)
The calculation of bursal index (BI) is obtained by the following formula: weight of Fabricius bursa / body weight x 100 (Bennet, 2002). Histological cuts of Fabricius bursa are prepared from broiler chickens of every flock according to the conventional method (Campell, 1995). Histopathological observation is realized thanks to an optic microscope AXIOSCOPZO - ICS – Zeiss-Germany. For the assessment of broiler chickens immune status, we used the method developed by Solvay (1992) based on the degree of severity of lymphocyte depletion in the medullary follicular zone of this organ. Statistical analysis was performed by SPSS 15.0. Factorial analysis of multiple correspondences (FAMC) realized to determine different class of bursal index and the correlation between the live weight of the chicken and that of the bursa Fabricius.
RESULTS AND DISCUSSION
The bursal index (BI) calculated during all the period of raising (49 day) for the 9 flocks of broiler chickens demonstrates that more than the half belong to the bad class (57.63%) and only a quarter belongs to the one excellent (27.75%), what confirms the heterogeneity of poultry flocks (Table 1).
Table 1. Bursal index (BI) in boiler flocks (%)
Figure 2. Correlation between body weight and bursal weight in the broiler chickens
It is a positive and significant correlation (p≤ 0.001), what explains that the weight of the bursal increased effectively according to the body weight, but without reaching some compliant values This variation of the bursal morphology demonstrates the immunodepression state at certain broilers chickens (Table 2).
Table 2. Lesion scores of bursa cloacae in broiler flocks (n = 62)
Lesional score survey demonstrated that more than the half (53%) of the examined organs present lesions of different degrees (Figures 3, 4, 5).
Figure 3. Left= Normal bursa. Right= Atrophied and hemorrhagic bursa
Figure 4. Lympho-epithelial follicles with clear medulla and dark cortical, a clear basal membrane as a chapelet (X40)
Figure 5 Intrafollicular cystic cavities and interstitial edema (X40)
The distribution of the observed lesions is very variable within the different flocks and even inside of one same flock. They are especially characterized by atrophy, lymphocyte depletion. In the more serious cases, one notes a follicular lymphoid necrosis, an interfollicular interstitial fibrosis and a degeneration of the coating epithelium (not mentioned). The observed lesions ofFabricius bursaare caused by a wild virus of IBD having infected broiler chickens since their arrival in the badly decontaminated buildings or by the vaccinal strain called "Intermediary plus". Researches demonstrated, that in spite of an elevated rate of maternal antibodies at broiler chicks, it can have precocious and lasting colonization of the bursa of Fabricius there by a wild strains (Pastoret and al., 1990). It exists an optimum moment of difficult vaccination to determine, it is necessary sufficiently of maternal antibodies to master a possible wild strain but not too much to not neutralize the vaccinal virus (Goutebroze and al., 2003; Lemiere, 2003). Boudaoud (2004, 2008) demonstrated the immunodepression and pathological state caused of “intermediate plus” vaccine strains against IBD with regard to those so-called “intermediate.”
CONCLUSION
The size and lesion scores of bursa Fabricius demonstrates that the immune status of broilers is below standard. Determining bursa: body weight ratio, morphometrical and histopathological studies, calculating of percentage and bursal index are easy ways and not expensive to evaluate the immune status in the broiler, which allows to identify the problem in time at the end to remedy and correct failures.
REFERENCES
Awad, MH, 2002. Immunity and immunosuppression in birds. Poultry Middle East and North Africa Magazine, 163: 21-22.
Bennet, C, 2002. How to score bursa size in broiler chicken flocks. University of Saskatchewan.
Boudaoud, A, 2004. Evaluation de l’innocuité de vaccins atténués de la maladie de Gumboro chez le poussin conventionnel. Mémoire magistère, Université de Batna, Algérie.
Boudaoud, A and Alloui, N, 2008. Evaluation of the safety of live attenued vaccine virus against infectious bursal disease in conventional broiler chicks. Revue science et technique. Office International Epizooties, 27(3), 793-802.
Campell, TW, 1995. Avian hematology and cytology. Iowa State University press/Ames.
Goutebroze, S, Curet, M, Jay, MJ, Roux, C and Le Gros FX, 2003. Efficacité d’un vaccin recombiné HVT-VP2 contre la maladie de Gumboro, en présence d’anticorps parentaux. V eme Journées Recheche Avicole, Tours, 305-308.
Kuney, D, 1982. Bursameter a tool for measuring the size of the bursa of Fabricius. Solvay Animal Health. USA.
Lemiere, S, 2003. Présentation d’un modèle permettant de déterminer la date de vaccination de la maladie de Gumboro du poulet de chair. V eme Journée Recherche Avicole, Tours, 335-338
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Pastoret, P, Gzovaerts, A and Basin, H. 1990. Immunologie Animale. Edit. Flammarion, France, 740p.
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This article was originally published in J. World's Poult. Res. 2(2): 37-39, 2012.
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