Influence of the rearing system on yolk corticosterone concentration in captive Greater Rheas (Rhea americana)

DELLA COSTA N. S.; MARIN R. H.; BUSSO, J. M.; HANSEN C.; NAVARRO, J. L.; MARTELLA M. B.

ZOO BIOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2016

0733-3188

Many environmental conditions elevate plasmacorticosterone in laying birds, leading to elevated hormone accumulation in theegg. We investigated whether maternal yolk corticosterone levels in GreaterRheas differ between fresh eggs collected from an intensive (IRS) and asemi-extensive (SRS) rearing system. After HPLC validation, yolk corticosteronewas measured using a corticosterone 125I radio-immunoassay kit. Results(mean ± SE) showed that eggs collected from the IRS exhibited a significantly highercorticosterone concentration than eggs from SRS (89.88 ± 8.93 vs. 45.41 ± 5.48ng/g yolk, respectively). Our findings suggest that rearing conditions under anintensive scheme (e.g. small pens with bare ground, no direct foraging and handling)might be perceived as more stressful for Greater Rhea females than semi-extensiverearing conditions (e.g. low animal density distributed in extensive areas anddirect foraging), which would result in the transfer of higher yolkcorticosterone levels. A better understanding of environmental conditions andfemale traits that affect yolk corticosterone deposition provides a background for futures studies concerning the roles ofmaternal corticosterone on offspring development.