Mycoplasma diseases in chickens include Mycoplasma gallisepticum infection and Mycoplasma synoviae infection. The pathogens are transmitted vertically and can keep a flock contaminated for a long time. They can reduce egg production, hatchability, and survival rates, posing a serious threat to the poultry industry. Breeder flock eradication should be carried out as follows:
1. Improve biosecurity and disinfection procedures. ① Before bringing in chicks or hatching eggs, first learn about the supplier flock’s disease history and eradication status; do not source from a flock with an outbreak. ② The poultry farm should be located far from major roads, residential areas, other livestock and poultry farms, and slaughterhouses or processing plants; visitors should not be admitted; staff and vehicles must undergo thorough disinfection before entering the farm. ③ Before chicks are brought into a poultry house, it should be disinfected by removing litter and waste, washing with high-pressure water, flame treatment, applying limewash, and fumigating with formalin in a sealed space. Where possible, leave the house empty for more than 2 weeks. ④ Thoroughly clean and disinfect the environment inside and outside the poultry houses regularly. ⑤ Throughout the rearing period, carry out in-house spray disinfection 2-3 times per week; if an outbreak occurs, disinfect birds in the house every day.
2. Carry out flock testing. One month before the breeder flock begins supplying hatching eggs, collect blood from each bird and test the entire flock using the whole-blood plate agglutination test; cull positive birds. Repeat the test after 1-2 weeks. The procedure is as follows: add 2 drops of antigen to a clean glass slide, then add 1 drops of blood from the bird being tested and mix. A bird is considered positive if an agglutination reaction appears within 2 minutes. If birds must be retained for breeding, strictly isolate the positive birds and administer planned drug treatment.
3, strictly disinfect and medicate hatching eggs. Hatching eggs should not remain in the henhouse for a long time; they should be collected 4 times a day. When the eggs are collected for setting and on day 19, when they are transferred to hatching trays, fumigate them with 28 ml/m3 formalin for 30 minutes. When approximately 50% of the chicks have hatched, fumigate in the hatcher with 10 ml/m3 formalin for 20 minutes. Before routine incubation, treat the hatching eggs with medication as follows: first warm them until the temperature inside the eggs reaches approximately 38℃, then immerse them in a medicated solution at 0–4℃ for 20 minutes. Allow them to air-dry, then continue incubation. The solution may be an aqueous solution of 500-1000 ppm tylosin, licomycin, Mycoplasma purifier, chloramphenicol, erythromycin, or 1% streptomycin, among others.
4, manage the flock scientifically. Mycoplasmosis in chickens is a chronic disease; when there are no complications, the mortality rate is low. However, stress factors can trigger an outbreak of mycoplasmosis and cause significant losses. The main stress factors include excessive flock density; sudden increases or decreases in temperature; poor ventilation, especially excessively high ammonia concentrations; deficiencies in feed nutrients; strong reactions to live attenuated vaccines; and infection with Newcastle disease or infectious bronchitis. Under the influence of stress factors, mycoplasmas multiply rapidly, weakening the chickens' resistance and making them susceptible to infection by Escherichia coli, staphylococci, or Salmonella, which can significantly increase morbidity and mortality. Therefore, during flock management, provide nutritionally complete, high-quality compound feed, maintain suitable temperature and humidity, ensure good ventilation, vaccinate against diseases such as Newcastle disease and infectious bronchitis, and try to avoid other stress factors that may disturb the flock.
5, carry out planned medication and prevention. Medication is essential for positive or suspected flocks. Mycoplasmas can form caseous material in the air sacs. Medication can kill only mycoplasmas outside the air sacs and has no effect on those in the air sacs. If stress factors arise, the mycoplasmas in the air sacs can multiply extensively and spread to other parts of the chicken's body, causing disease. Therefore, although many antibiotics are effective against mycoplasmosis, no single drug can eradicate the disease. Two or more drugs should be selected and used alternately over an extended period. An ideal approach is to mix one antibiotic into the feed and administer it for 1 weeks each month, extending the course if necessary. Antibiotics that may be used include: tylosin at 0.1% in feed; doxycycline at 0.01%-0.02% in feed; chloramphenicol at 0.025%-0.04% in feed; kitasamycin at 0.033%-0.05% in feed; erythromycin at 0.013%-0.025% in feed; and others. For severely ill chickens, streptomycin may be injected intramuscularly at 10-20 ten-thousand units per chicken, 2 times a day for 3 days.
6, vaccinate as appropriate based on the local disease situation. Studies show that vaccinating breeder flocks with an inactivated Mycoplasma oil-emulsion vaccine does not protect chicks from Mycoplasma infection, but can largely prevent vertical transmission of Mycoplasma through hatching eggs to the next generation. Vaccinating breeder chickens once with an inactivated oil-emulsion vaccine before they start laying, then vaccinating again after 3-5 months, is beneficial for improving the quality of hatching eggs and chicks.