Reproductive endocrine responses to photoperiod and exogenous gonadotropins in the Pallas' cat (Otocolobus manul)

Fecal samples were collected for 14-26 months from three male and six female Pallas' cats (Otocolobus manul) to examine gonadal steroidogenie activity in response to changes in photoperiod and treatment with exogenous gonadotropins. Females exhibited a seasonal anestrus from May-December, excreting consistently low concentrations of fecal estrogens (overall mean. 50.2+/-8.5 ng/g). During the breeding season (January-April), baseline fecal estrogen concentrations were higher, averaging 128.4+/-18.9 ng/g, with peak concentrations ranging from 455.8-909.6 ng/g. Interpeak intervals in estrogen excretion ranged between 7 and 21 days, with an average estrous cycle length of 14.3 +/- 1.7 days. Two females became pregnant after natural mating, with overall luteal progestogen concentrations averaging similar to40 mug/g throughout gestation. Fecal estrogens increased in mid-gestation, peaking just before birth. Induction of follicular development with eCG (100-300 IU, i.m.) resulted in an increase in fecal estrogens (peak range, 263.1-1198.1 ng/g), followed by a postovulatory increase in fecal progestogens (overall mean, 41.1+/-11.9 mug/g) after hCG (75-150 IU, i.m.). Despite apparently normal ovarian responses, none of the females conceived after artificial insemination (AI). The gonadotropin-induced nonpregnant luteal phase lasted 49.8+/-5.3 days (range, 30-60 days), whereas gestation lasted similar to70 days. In the male Pallas' cat, fecal androgens were elevated from November-April (overall mean, 352.3 +/- 30.3 ng/g) compared with nadir concentrations during the rest of the year (82.1 +/- 3.3 ng/g). Entrainment of seasonality to photoperiod was demonstrated by stimulation of gonadal steroidogenic activity in cats exposed to increasing artificial light during natural (nonbreeding season) and artificially induced short-day photoperiods. In summary, reproduction in Pallas' cats is highly seasonal and photoperiod-dependent. Females exhibit elevated baseline and peak fecal estrogen concentrations for 3-4 months during late winter/early spring. Testicular steroidogenic activity precedes the rise in female estrogen excretion by about 2 months, presumably to ensure maximal sperm production during the breeding season. Published 2002 Wiley-Liss, Inc.(dagger)