MATERNAL IMMUNOGLOBULIN-G ANTIBODY TRANSFER AND DEVELOPMENT OF IMMUNOGLOBULIN-G ANTIBODY-RESPONSES IN BLUE AND GOLD MACAW (ARA-ARARAUNA) CHICKS

Objective-To document the maternal transfer of IgG antibodies from Blu e and Gold Macaw hens to chicks via the egg; to measure serum IgG half -life in macaw chicks; and to measure the ability of 2- to 10-week-old macaw chicks to generate primary and secondary IgG responses. Procedu re-4 adult Blue and Gold Macaw hens were inoculated with 200 mu g of b ovine serum albumin (BSA) every 21 days throughout the breeding season . Eggs laid by these hens were incubator hatched to eliminate the poss ibility of antibody transfer through crop secretions during feeding. A nti-BSA titer was measured just prior to each inoculation in hens and in chicks from 14 to 42 days of age. 1 chick from each of 5 macaw clut ches hatched to nonimmunized hens was assigned to 1 of 2 experimental groups. Group-1 chicks were inoculated with 200 mu g of BSA at 2 and 6 weeks of age. Group-2 chicks were inoculated with 200 mu g of BSA at 6 and 10 weeks of age. Anti-BSA titer was measured weekly for 8 weeks after primary inoculation. Blood samples were centrifuged, and serum w as harvested and frozen at -85 C until analyzed. Anti-BSA IgG titers w ere measured by ELISA. In the maternal transfer experiment, an exponen tial decay model was used to calculate the half-life of BSA antibodies in chicks. In the BSA antibody response experiment, comparison of pri mary and secondary anti-BSA responses of 2- and 6-week-old chicks was performed, using a two-way repeated measures ANOVA, with significance set at P < 0.05. Results-Hens maintained high anti-BSA titer throughou t the breeding season. Maternal transfer of anti-BSA IgG antibodies wa s documented in all 7 chicks. Anti-BSA titer in chicks decreased in ex ponential fashion with an average serum IgG half-life of 3.85 days. By 42 days of age, antibodies to BSA were virtually undetectable in all chicks. The primary antibody response of 6-week-old chicks was signifi cantly higher than that of 2-week-old chicks (P = 0.016). No significa nt difference was observed in the magnitude of the secondary antibody responses between these age groups. Peak anti-BSA IgG antibody respons es were reached by 14 days after primary and secondary immunization. C hicks of both age groups generated lower anti-BSA IgG titer than did a dult Blue and Gold Macaws. Conclusions-Blue and Gold Macaw hens transf er IgG antibodies to their chicks through the egg. The half-life of Ig G in newly hatched chicks is approximately 3.85 days. 6-week-old chick s develop higher anti-BSA titers than do 2-week-old chicks, but signif icantly lower titers than do adult macaws. Clinical Relevance-Informat ion on the nondomestic avian immune system will be useful in the devel opment of vaccination and other preventive health programs for psittac ine birds.