Though the age difference in serum IgG level of the chicken has been investigated by some researchers, it of the quail has not been reported. The present studies were carried out using a single radial immunodiffusion technique to clearify the change of serum immunoglobulin G (IgG) level of the Japanese quail (Coturnix coturnix japonica) with aging. The differences of the serum IgG levels between sexes and among three strains of the Japanese quail was investigated.
IgG was isolated from a normal, unimmunized adult Japanese quail serum by the precipitation with ammonium sulphate, the technique of agar block electrophoresis and gel filtration on Sephadex G-200. Anti-IgG serum was prepared by the injection of emulsion of the quail IgG with Freund's complete adjuvant into the rabbits. The IgG levels of sera of Japanese quail were determined by a single radial immunodiffusion technique (MANCINI et al., 1965).
The serum IgG levels in wild feather color strain (A), silver ferther color strain (B) and white shell with wild feather color strain (C) were determined from 0 to 30 weeks of age. The IgG level at 0 week decreased drastically until 1 or 2 weeks of age, and then it increased until 15 weeks of age. At 0 week of age, serum IgG levels for males of A, B and C strain were 428.7mg/100ml, 360.1 and 312.6, respectively, and those for females of each strain were 399.6, 360.0 and 367.2, respectively. The values reached 672.3, 454.9, 647.3 for males and 518.0, 324.5, 474.0 for females at 10 weeks of age. The serum IgG level of A strain was significantly higher than that of B strain at 0 and 2 weeks of age and thereafter. A sexual difference in serum IgG levels was observed at 10 weeks in each strain, and at 15 weeks in B strain. The IgG levels of males were significantly higher than those of females at these weeks of age.