SHORT NATURAL PHOTOPERIOD STIMULATES TESTICULAR ACTIVITY OF CHINCHILLA

BUSSO JM; PONZIO MF; DOMINCHIN MF; FIOL DE CUNEO M; RUIZ RD

BIOCELL

INST HISTOL EMBRIOL-CONICET

Lugar: Mendoza; Año: 2011 vol. 35 p. 295 - 295

0327-9545

Hystricomorphic rodents are particularly well represented in South America; among them, Chinchilla spp is threatened and the presence of remaining colonies in the Argentinean Andes is uncertain, although a domestic form is widespread in breeding farms. Chinchilla lanigera exhibits reproductive rhythms with two breeding peaks in spring and summer; however, there are not studies about photoperiod effects on its reproductive physiology. Domesticated males (n=7) were studied to determine the effects of natural photoperiod upon testicular activity in Córdoba (31°S 64°W) during May, August, November, and February; urine (24h) was obtained before to semen collection by electroejaculation. Differences in androgen excretion (ng/mg of creatinine) were detected by repeated measures ANOVA, the highest values were found associated with 'short' light/dark cycles (autumn-winter); acrosome intact sperm percentages were higher during winter-spring than summer-autumn, and the lowest sperm concentration was detected in summer (p less than 0,05). However, seminal volume and sperm functional activity showed non significant seasonal changes. These results suggest that the chinchilla male gonadal activity is affected by natural photoperiod; therefore, it is possible to postulate that this species would be a 'short-day' breeder. Supported by grants from SECyT-UNC, CONICET, FONCyT.