Characterization of seasonal reproduction patterns in female pichis, Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal sex steroid metabolites and ovarian histology.

SUPERINA M.; CARREÑO N.B.; JAHN G.A.

ANIMAL REPRODUCTION SCIENCE

Elsevier

Lugar: New York; Año: 2009 vol. 116 p. 358 - 369

0378-4320

Reproductive strategies vary considerably among species, but most studies have focused on a very limited number of mammalian species. Knowledge of the reproductive cycle and behavior is essential for developing and implementing in situ and ex situ conservation strategies for threatened and endangered species. We aimed at characterizing the annual reproductive cycle of female pichis Zaedyus pichiy, a threatened small armadillo native to arid regions of Argentina and Chile, through direct observations, histological studies, and by measuring fecal immunoreactive estrogens and progestagens in 10 wild-born, semi-captive pichis and in free-ranging individuals. Our results suggest that pichis are seasonal breeders that give birth to one yearly litter of 1 to 2 offspring, which do not leave the burrow until they are weaned at approximately 35 days. Follicular growth seems to occur during all of the year and during pregnancy and lactation, but we could not observe any clear patterns in fecal hormone metabolites in non-pregnant females suggestive of ovulatory cycles. Fecal progestagen and estrogen levels remained low during the first half of pregnancy, increased to peak levels of up to 3500 ng/g and 200 ng/g dry feces, respectively, and fell sharply prior to parturition. Postpartum progestagen levels were significantly higher in lactating females than in females that aborted or did not raise their offspring, which is probably related to an elevated corticosteroid synthesis to maintain lactation.