Resumen

GARCIA-FERIA, Luis M.  y  VALDESPINO, Carolina. Evaluation of fecal sex steroids in captive horned guan (Oreophasis derbianus, Aves: Cracidae). Acta Zool. Mex [online]. 2015, vol.31, n.1, pp.1-9. ISSN 2448-8445.

The measurement of sexual steroids over time allows evaluating the changes in reproductive function of individuals. We evaluate the profiles of fecal testosterone (T_f) and fecal estradiol (E_2f) of three males and four females of Oreophasis derbianus (Aves: Cracidae) in a breeding program. Sex steroids faecal samples were quantified by a chemoluminiscence immunoassay. There are not significant differences in the T_f concentrations between males (P = 0.894) and along the sampling time (P = 0.305), but there was a hormone pattern corresponding with monogamous mating system, even when the polygyny has been reported in this bird. One of the individuals had higher concentrations E_2f (34.09 ± 1.08 ng/g) than the other two (6.83 ± 1.38 and 7.98 ± 2.13 ng/g), suggesting a greater reproductive age, as has been previously reported that this hormone increases with senescence. The females did no show significant differences between them (P = 0.473) and along sampling time (P = 0.668). The evaluation of the concentrations of both steroids in the same individual and their ratio allowed defining that the hormonal activity corresponds to the traditionally assigned to each sex, where males show T_f concentrations larger than females and the opposite in the case of E_2f. The E_2f/T_f ratio is therefore greater in females. In captivity, estimate the gonadal activity to determine the success or reproductive failure, assess sexual maturity and fertility of wild animals, allow determining if an individual or group has the ability to reproduce and become part of a breeding program.

Palabras llave : Oreophasis derbianus; fecal steroids; non invasive sampling; monogamy; senescence.

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