The Effect of Mycoplasma synoviae on Meat Type Hens Exposed by Injection into Air Sacs, Foot Pads and Trachea and by Aerosol

Abstract A total of thirty-seven 32-week-old meat-type females, free from Mycoplasma synoviae (Ms.) and Mycoplasma gallisepticum (Mg.), were exposed to a 24-hour broth culture of a recent Ms. isolate from the trachea of a chicken that had been artificially infected with Ms. by aerosol. Three-tenth ml. of Ms. broth culture was injected into the left foot pads of 10 females; 0.3 ml. was injected into the left thoracic air sacs of 9 females; 0.3 ml. was injected into the trachea of 10 females, and 8 females were exposed by aerosol for 8 minutes. The hens were placed in Pens A, B, C and D, respectively. To produce fertile eggs one male was placed in each of the 4 pens. All birds were bled at 2, 4, 7, 10, 15, 25, 27, 31 and 37 weeks after Ms. exposure. After the 25-week bleeding, one-half of the number of hens in Pen A were placed in Pen B, and one-half of the females in Pen B were placed in Pen A. The same procedure was followed for Pens C and D. Each female in Pens B and D received an injection of 0.3 ml. of a 24-hour broth culture of Ms. 1331 into the right foot pad to see the effect of a Ms. challenge on the geometric mean hemagglutination-inhibition (HI) titers and Ms. ioslations from the progeny. Ms. isolation attempts were made from the trachea of each female at 4, 15 and 25 weeks after Ms. exposure. From the eggs produced Ms. isolation attempts were made from either the allantoic fluid and egg yolk of 17- or 18-day-old embryos, or dead embryos or from the tracheas of day-old progenies. Thirty-one weeks after Ms. exposure, an equal number of Mycoplasma-free, 30-week-old meat-type hens were placed in each of the 4 pens as contact birds. The contact birds were bled at 0, 3, 6, 10 and 14 weeks after initial contact with Ms.-exposed females and were tested by the Ms. HI test. Ms. isolation attempts were made from trachea swabs from each of the contact female birds at 6 and 10 weeks after contact. At each bleeding the Ms. geometric mean HI titers of the Ms.-aerosoled females were significantly higher than those of the females exposed by the other three methods of Ms. exposure. A Ms. 1331 broth culture injected into the foot pads 25 weeks after Ms. exposure did not significantly increase the geometric mean HI titers at 2, 6 and 12 weeks after foot pad challenge. For each method of Ms. exposure, the Ms. isolations from the trachea were from 90.0 to 100.0%. There were 2, 2, 9 and 5 Ms. isolates made from embryonated eggs or from the trachea of day-old progeny from females exposed by foot pad, air sac, trachea and aerosol, respectively. From the 18 isolates, 16 were from eggs collected within 28 days after Ms. exposure of the females. Ms. was isolated from the trachea of 14 of the 32 contact females 6 weeks after contact, and 25 isolations were made 10 weeks after contact. The percentages of serum from the contact females that were positive to the Ms. HI test were 0, 3.12, 46.87, 84.38 and 96.88 when bled at 0, 3, 6, 10 and 14 weeks after contact, respectively. No Ms. was isolated from any of the eggs collected from the contact females.