The aim of this study was to analyse ovarian activity and pregnancy in 140 Pura Raza Espanola mares over a period of two consecutive years. The data were analysed using SPSS software to evaluate the effects of age, category of mares and season on pre-ovulatory follicle size, ovulation rate, interval from foaling to pregnancy, gestation length, incidence of twin pregnancies and pregnancy losses. The results showed that follicular diameter was significantly (P < 0.05) smaller in fillies (3-year-old) and maiden mares than in older and multiparous mares. Within the group of animals treated with gonadotropin hormone hCG, 87.23% ovulated 48 h following administration. Length of gestation varied from 305 to 356 days and all gestation pregnancies of less than 305 days resulted in a non-viable foal. In addition, foaling season affected (P < 0.05) the post-partum conception interval and the length of gestation, which were shorter and longer in the winter foaling, respectively. Regarding the other parameters, mares of this stud exhibited relatively very low rates of double ovulations, twin pregnancies and pregnancy losses. We conclude that age and category of mares and foaling season influence fertility and foaling rates by affecting pre-ovulatory follicle size, pregnancy loss and gestation length.

Surgical castration in ferrets has been implicated as an etiological factor in the development of hyperadrenocorticism in this species due to a castration-related increase in plasma gonadotropins. In search for a suitable alternative, the effect of treatment with the depot GnRH-agonist implant, deslorelin, on plasma testosterone concentrations and concurrent testes size, spermatogenesis, and the typical musky odor of intact male ferrets was investigated. Twenty-one male ferrets, equally divided into three groups, were either surgically castrated, received a slow release deslorelin implant or received a placebo implant. Plasma FSH and testosterone concentrations, testis size and spermatogenesis were all suppressed after the use of the deslorelin implant. The musky odor in the ferrets which had received a deslorelin implant was less compared to the ferrets which were either surgically castrated or had received a placebo implant. These results indicate that the deslorelin implant effectively prevents reproduction and the musky odor of intact male ferrets and is therefore considered a suitable alternative for surgical castration in these animals. (C) 2008 Elsevier Inc. All rights reserved.