[in Japanese]

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A total of 151 chickens of age 52-111 days were inoculated with Mycoplasma gallisepticum (MG)(Strain 5) directly into the left posterior thoracic air sac (PAs), the wing vein, and also by the combined airsac and intravenous (IV) routes. Prior to each experiment and once a week usually for the first 4 weeks following inoculation, the birds were examined every day for clinical signs and bled once a week. The blood samples used for the rapid serum plate test of MG had previously been proved to be free from infectious bronchitis and Haemophilus gallinarum infection before the start of each experiment. The birds were usually sacrificed for necropsy 4 weeks after inoculation. They were given a diet weighing 116 g per head per day ad libitum.
No changes in temperature were remarkable. In all the chickens, appetite was hardly reduced through, out the course of the experiment. A food residue which averaged 5-27 g, with a maximum of 40 gper head per day was found among the birds of the experimental group over a period from the 9th to 13th day after the MG inoculation. No exact amount of food residue, however, could be determined in any group due to the periodical sacrifice of the birds.
Many of the uninfected, untreated chickens showed no gain in body weight superior to those infected. On the other hand, a few of them showed superior gain in weight. All the birds infected with MG by the intravenous or the combined route gave a positive serological reaction to MG on the third day following inoculation. All the birds infected by the PAs route alone were positive on the 7th day, except two which were positive on the 6th day. Only two of the 151 infected chickens manifested clinical signs.
M. gallisepticum was recovered from the left PAs in 62 birds (72.9%), from the trachea in 46 birds (54.1%), from the infraorbital sinus in 11 birds (24.4%), from the lung in 23 birds (51.1%) out of a total of 85 birds inoculated with MG into the left PAs. No causative agents were isolated from the left PAs, trachea, infraorbital sinus, or lung examined in 24 birds out of inoculated intravenously with MG.

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