White Rock and White Leghorn chickens bursectomized between 1 and 5 weeks of age were challenged with bovine serum albumin at 6 weeks of age. The effect of bursectomy on precipitin production gradually became less during this period. There appeared to be a breed difference in response, as bursectomy at 4 and 5 weeks of age significantly lowered the response of White Rocks whereas bursectomy at 4 weeks did not affect the response of White Leghorns.
The development of natural antirabbit hemagglutinins was also affected by bursectomy. White Leghorns bursectomized at 1 week of age did not exhibit hemagglutinin titers until 9 weeks of age, and those bursectomized at 10 days did not begin to show titers until 6 weeks of age. All control birds had titers by 5 weeks of age. Groups bursectomized between 2 and 4 weeks of age were also delayed in attaining the control titer but did so by 9 or 12 weeks of age. These hemagglutinins may be produced in response to some unidentified antigen.
The observed reduction in antibody production following bursectomy may have been influenced by the induction of at least a degree of unresponsiveness in some birds.