title: Influence of the rearing system on yolk corticosterone concentration in captive Greater Rheas (Rhea americana).
abstract: Many environmental conditions elevate plasma corticosterone in laying birds, leading to elevated hormone accumulation in the egg. We investigated whether maternal yolk corticosterone levels in Greater Rheas differ between fresh eggs collected from an intensive (IRS) and a semi-extensive (SRS) rearing system. After HPLC validation, yolk corticosterone was measured using a corticosterone (125) I radio-immunoassay kit. Results (mean ± SE) showed that eggs collected from the IRS exhibited a significantly higher corticosterone concentration than eggs from SRS (89.88 ± 8.93 vs. 45.41 ± 5.48 ng/g yolk, respectively). Our findings suggest that rearing conditions under an intensive 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-extensive rearing conditions (e.g., low animal density distributed in extensive areas and direct foraging), which would result in the transfer of higher yolk corticosterone levels. A better understanding of environmental conditions and female traits that affect yolk corticosterone deposition provides a background for future studies concerning the roles of maternal corticosterone on offspring development. Zoo Biol. 35:246-250, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Rondeau 798, (X5000AVP) Córdoba, Argentina.
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Della Costa
authors.affiliation: Instituto de Investigaciones Biológicas y Tecnológicas, Instituto de Ciencia y Tecnología de los Alimentos, (IIBYT, CONICET-UNC), and Cátedra de Química Biológica, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, (X5000AVP) Córdoba, Argentina.
authors.forename: Raul H
authors.initials: RH
authors.lastname: Marin
authors.affiliation: Instituto de Investigaciones Biológicas y Tecnológicas, Instituto de Ciencia y Tecnología de los Alimentos, (IIBYT, CONICET-UNC), and Cátedra de Química Biológica, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, (X5000AVP) Córdoba, Argentina.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Busso
authors.affiliation: Laboratorio de Análisis Clínicos Especializados (LACE), Av. Vélez Sársfield 562, (X5000AVP) Córdoba, Argentina.
authors.forename: Cristian
authors.initials: C
authors.lastname: Hansen
authors.affiliation: Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Rondeau 798, (X5000AVP) Córdoba, Argentina.
authors.forename: Joaquín L
authors.initials: JL
authors.lastname: Navarro
authors.affiliation: Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Rondeau 798, (X5000AVP) Córdoba, Argentina.
authors.forename: Mónica B
authors.initials: MB
authors.lastname: Martella
mesh_terms: D000822:Animal Husbandry / Q000592:standards; D000818:Animals; D000836:Animals, Zoo / Q000502:physiology*; D003345:Corticosterone / Q000032:analysis / Q000378:metabolism*; D004530:Egg Yolk / Q000737:chemistry*; D004777:Environment; D005260:Female; D020311:Rheiformes / Q000378:metabolism / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D003345:Corticosterone
keywords: eggs; maternal stress; ratites