A study was conducted to assess the effects of aflatoxin contaminated feed on the immunoresponse of one-day old layer chicks to attenuated live virus vaccines for Newcastle disease (ND), infectious bronchitis (IB) and infectious bursal disease (IBD). Concurrent exposure of chickens to 2tiO parts per billion (ppb) aflatoxin in feed and vaccination against ND, IB and IBD resulted in lack of adequate protection against subsequent experimental challenge, as assessed by antibody responses compared to chickens fed aflatoxinfree ration. The mortalities were higher in chickens fed 200 ppb of aflatoxin than in chickens fed on aflatoxin-free ration.

A study was conducted on the impact of aflatoxin in the feed on the prophylactic immunization of layer hens against Newcastle disease, infectious bronchitis, infectious bursal disease and fowl cholera. Fourhundred-and-eighty 18-week-old white leghorn chickens were used. Different groups of hens were vaccinated, as per commercial recommendations, with a commercial inactivated triple vaccine against Newcastle disease, infectious bronchitis, and infectious bursal disease. A killed polyvalent bacterin was used for fowl cholera. Aflatoxin was fed for 22 weeks at a daily dose of 200 parts/10 9 /hen. Aflatoxin significantly reduced antibody titres, resulted in a decrease of egg weight, a decrease in egg production and an increase of mortality rate in challenged hens. Aflatoxin was detected in eggs at levels far above the permissible concentration.

SUMMARYA study was conducted on the impact of aflatoxin in the feed on immunization against infectious bursal disease (IBD) in chickens using an attenuated live vaccine. Three-hundred-and-ninety broiler chicks were used. The aflatoxin feeding of 100 and 200 parts/10 9 of AFBI started when chicks were 10 days old and continued for 8 weeks. An attenuated live IBD virus vaccine was administered in drinking water at 2 and 5 weeks of age. A field IBD virus strain was used for challenge. The antibody titres, bursal indices, bursal lymphocyte counts and feed conversion ratios were monitored. The impact of aflatoxin on reduced body weights and lower antibody titres was shown to be highly significant (P<0.0001).

A total of 1,175 poultry feed samples originating from different farms were analyzed for aflatoxin. Poor growth rate and reduced egg production were the main complaints. The rate of contamination with aflatoxin ranged from 10 to 54% of all samples. Of samples examined 30.7% proved positive for aflatoxin with a concentration ranging from 1 to 2,000 ppb. Outbreaks of fowl cholera were diagnosed on two farms where aflatoxin was detected in the rations used. The impact of aflatoxin in the feed on the efficacy of immunization against fowl cholera was monitored by a hemagglutination test and the titers of the involved farms were compared with experimental groups fed on aflatoxin-free rations and vaccinated with the same polyvalent fowl cholera bacterin. The antibody titers of the experimental groups were 4 to 15 times higher than those of the involved farms.

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