A total number of two hundreds of one day old quails were grouped into four groups (50 for each). The quials in the 1st and 2nd groups were received aflatoxin Bl at the levels of 1.25 and 2.5 micro g/ g of diet for 7 successive weeks. The first, second and third groups were vaccinated with fowl cholera vaccine but the 4th group was kept as a control non toxicated non vaccinated. For the evaluation of the cell mediated immune response of quails toxicated with aflatoxin Bland after that vaccinated with fowl cholera vaccine, the mitogenic re¬sponse of peripheral blood lymphocytes was estimated using concanavalin-A as T-cell mitogen and pookeweed as B-cell mitogen.
The obtained results revealed that the aflatoxin Bl at the levels of 1.25 and 2.5 g of diet induced strongest immuno-suppressive effect from the 4th to 7th week after administration of the aflatoxin in the diet due to the deficiency in the systemic cell mediated response. Also, aflatoxins were capable of exerting their direct effect on the blastogenic differentiation of B-lymphocytes and consequently decrease the immune response of quails to fowl cholera vaccine and decreasing the efficiency of the vaccine.
The over all mean of the immunoglobulin G (IgG) levels at the aflatoxin Bl at the levels of 1.25 and 2.5 fig/ g of diet were ( 574.4 and 550.2 mg/l00ml) respectively, in compari¬son to the non toxicated vaccinated and non toxicated non vaccinated groups which are (997.4 and 604.2 mg/l00ml) respectively.
The protection rate was 80% in the non toxicated vaccinated quails after challenge with P. multocida (5:A, 8:A and 9:A) and 30% in non toxicated non vaccinated quails "but the protection rate reached 35% and 25% in the toxicated vaccinated groups at the aflatoxin Bl at the levels of 1.25 and 2.5 micro g/ g of diet respectively.
A significant depression in the body weights was observed from the beginning of the 4th week of age of quails fed on diet contaminated with aflatoxin. In the present work, it can be concluded that the presence of aflatoxins in the diet of quail farms induces immuno-suppressive effect and lead to failure in the immunization against fowl cholera.
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