| Weak chicken is also called the second-grade chicken or the third-grade chicken which have illness symptom or bad health status. The quality of chicken becomes more and more important for the benefit of breeding industry. The higher rate of weak chicken is, the lower benefit of breeding industry. The problem of weak chicken causes more and more attention of breeders, the high rate of weak chicken will bring breeding industry large economic loss. The experiment gives primary research into pathogenic microbe of weak chicken. We choose 60(30 AA meat chickens,30 Hy-line Brown) weak chickens(the second-grade chicken) as object meanwhile the same 60 normal chicken as contract and observe the illness status of the weak chicken, record the amount of the ill and the death. We give no immunization and no medicine in the feed to the object, the test lasts 9 days. We collect blood from experimental group at the seventh and tenth day to test the ND and AI antibody level, and then kill the left live chickens and observe the pathologic change of the whole 60 chickens. We choose part with pathological change to do experimental diagnosis including bacteriological test,serological test,virological test. The experiment indicates that most of the weak chicken have low spirit, abnormal waste, some one cough, the navel are not close wholly, belly bugled, more than 80 percent chickens yolks are not absorbed well. The heart shows fibrino-pericarditis, livers swelling, kidney's denaturalization and swelling and uric acid salt sediment. By the microscope ,we can see granular degeneration, fatty degeneration and putrescence in liver, fatty degeneration in kidney, uric acid salt sediment in small pipe of kidney, thymus, bursa of Fabricius spleen are not developed well; ND, AI's antibody level is lower than 2—3 degree. The result shows that ND, AI and IBD are not factor of the disease, E.coli and S.gallinaum are the main factor of weak chicken disease, the theories of the necessity for us to grow the germ...
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