Four viral diseases that can lead to a decline in egg production in laying hens

1. Overview of chicken Newcastle disease 1: an acute and severe infectious disease characterized by dysentery, dyspnea and neurological symptoms in chickens of all ages. It can be divided into four types: the most acute, acute, subacute and chronic. The most acute and acute chicken plague has a short onset time and high mortality; subacute and chronic chicken plague, sometimes also known as atypical chicken plague, have a great impact on chicken egg production. Chickens with atypical chicken plague generally show respiratory symptoms: coughing, rale, dyspnea, eyelid swelling, shrunken crown and purple color, and eggs are reduced by 20% to 30% when sick chickens sometimes pull yellow or green thin feces seriously, sometimes up to more than 50%. The egg quality decreases, the white shell egg, the soft shell egg, the abnormal egg increases, opens the egg, the protein is as thin as water. 2. Autopsy: congestion or bleeding of trachea, enlargement of paranasal sinuses, exfoliation of glandular gastric mucosa, bleeding or swelling of nipples, and bleeding of muscle and stomach in severe cases. Extensive bleeding of duodenum and small intestine and jujube-shaped ulcerative bleeding of small intestine have typical diagnostic meaning. Diffuse rectal bleeding, cecal lymph node enlargement and bleeding also have diagnostic significance. The egg yolks of laying hens are purple or congested, and in severe cases there are hysteritis or salpingitis. 3. Countermeasures: emergency vaccination of ND Ⅳ vaccine, 3-4 feather doses per mouse. In order to prevent secondary E. coli, antibiotics can be used to drink water for 3 days for 4 days. Avian influenza 1. Overview: avian influenza (A1) is an acute and highly contagious disease caused by type A virus. The disease can occur all the year round, regardless of variety and age, especially in the cold season. Birds, humans and lower mammals are susceptible to influenza A virus. The clinical symptoms of chickens infected with avian influenza are diverse, which can be divided into respiratory type, nervous type and reproductive type. The diseased chicken has elevated body and depressed spirit; cough, rale, tears, swelling of face and head, purple phosphorus slices of chicken crown, meat beard, skin and toes; yellowing and white thin feces, the number of eggs decreased, and the number of deformed eggs, discolored eggs and soft shell eggs increased; some are accompanied by neurological symptoms. 2. Autopsy: head edema and droop, chicken crown, leg cyanosis, congestion; tracheal mucosal edema, congestion, serous or caseous secretions; sinus swelling, air sac swelling, thickening and fibrinous or caseous exudates; liver and spleen swelling and necrosis; glandular stomach nipple ulcer, bleeding, intestinal extensive bleeding; follicular swelling, hyperemia, fallopian tube congestion, sometimes accompanied by yolk peritonitis. 3. Countermeasures: there is no effective chemical drug for the treatment of this disease, and floxacin drugs can be used to prevent bacterial infection. Usually, prevention should be given priority to, and oil emulsion inactivated vaccine should be used for immunization in the epidemic area. The diseased chickens were eliminated. 3. Egg drop syndrome 1. Summary: the disease mainly occurs in laying hens and young hens. Other day-old chickens can be infected, but there are no symptoms of the disease. It is also seen in 25-34-week-old hens during the peak laying period. At the onset of the disease, the spirit, feeding, drinking water and feces of the diseased chickens were basically normal, and the egg production decreased seriously day by day. The eggshell color becomes lighter or there are a large number of thin-shell eggs, soft-preserved eggs, shellless eggs and deformed eggs. It generally lasts for about 3 weeks, and then slowly picks up, varying in speed, and sometimes it is possible to return to the original level. 2. Autopsy: EDS-76 lacks characteristic lesions, sometimes catarrhal enteritis, ovarian atrophy or bleeding, inflammation of uterus and fallopian tube, white exudate in fallopian tube lumen, mucosal edema, pallor and hypertrophy. 3. Countermeasures: inoculating EDS oil emulsion inactivated vaccine before giving birth can prevent the occurrence of this disease. Eliminate infected chickens and do a good job in disinfection and hygiene. Infectious bronchitis 1. Overview: infectious bronchitis (1B) is an acute respiratory disease with a high degree of contact transmission, characterized by trachea sounds, coughing and sneezing. At present, it can be divided into respiratory type, renal type, reproductive type and proventriculus type. The main results were as follows: (1) the chickens infected with reproductive transmission had respiratory symptoms and decreased laying rate, as well as soft shell eggs, deformed eggs, sand preserved eggs, light colored eggs and white preserved eggs, which were easy to detach from the yolk. Yolk peritonitis can be caused in severe cases. (2) the respiratory type transmission branch is accompanied by renal type transfer branch, which leads to diarrhea and serious damage to the kidney. uric acid is no longer excreted with feces, resulting in urate deposition, that is, visceral gout. (3) the proventriculus type chicken gradually lost weight, with loose feathers, standing stiff, drooping wings, weight loss, sometimes accompanied by respiratory symptoms, cough, ringing and so on. 2. Partial examination: there were serous or catarrhal exudates in trachea, nasal passages and sinuses of diseased chickens, airbag turbidity, yellow caseous exudates, glandular gastric mucosal edema, severe enlargement of glandular stomach and obvious thickening of glandular stomach wall in chickens with glandular gastritis. Mucus in the trachea and annular bleeding occurred in a few sticky models, such as ulcer bleeding, liver stasis, spleen swelling and lung congestion. The follicles are congested, bleeding or atrophied, the fallopian tubes are shortened, the mucosa becomes thick and rough, the kidneys are swollen and pale, the renal tubules and ureters are filled with urate, and the rectal mucosa is striped with a large amount of calcareous feces in the cloaca.