Physiological stress response of captive Greater Rhea (Rhea Americana).

LECHE ALVINA; BUSSO JUAN MANUEL; HANSEN CRISTIAN,; NAVARRO JOAQUÍN; MARÍN RAÚL,; MARTELLA MÓNICA BEATRIZ

Brisbane, Australia

Congreso; World´ss Poultry Science Journal; 2008

The Greater Rhea is endangered in the wild and it is raised in commercial farms. Stress contributes to the development of diseases and disorders that cause high mortality in this species. High-performance liquid chromatography showed corticosterone as the primary glucocorticoid present in Greater Rhea. The adrenocortical response induced by an ACTH challenge was evaluated, and a 125I-corticosterone radioimmunoassay was validated for corticosterone measurements in plasma samples (parallelism: R2=0.97, p=0.19; assay accuracy: y=1.11x + 19.72, and assay precision: intra- and inter-assay variation <10%). Six 10-months old birds (three sub-adults of each sex) reared in captivity received an ACTH intravenous administration (5 IU/Kg). Blood samples were collected at 0 (baseline level), 15, 30 and 60min and 24 and 48h after ACTH administration. The repeated measures ANOVA examined the effects of sex and time after ACTH challenge and detected no effect of sex nor an interaction, therefore, male and female data were pooled. Corticosterone levels (mean ± SE) increased from 3.98 ± 1.04 ng/mL to 89.83 ± 12.42, 141.6 ± 21.98 and 166.54 ± 16.01 ng/mL respectively at 0, 15, 30 and 60min post ACTH administration. No differences between the samples taken at 0, 24 and 48h were found. This study constitutes a baseline for future investigations on stress physiology in this ratite.