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The Martina Franca (MF) donkey breed, with 48 jackasses and 515 jennies, is considered an endangered breed according to the data from the Monitoring Institute for Rare Breeds and Seeds in Europe. The knowledge of the estrous cycle characteristics has a great impact for assisted reproduction, especially in endangered species. In this study, the estrous cycle characteristics were investigated in 12 MF jennies throughout the year. Estrous cycle, estrous and diestrous lengths, follicular growth and ovulation, and estradiol-17β (E2) and progesterone (P4) plasma concentrations were monitored in MF jennies and compared in different seasons. In all jennies (100%) estrous cycle was detected during the whole year, with no differences in the estrous cycle length among seasons. However, a significant increase of estrous length in spring and summer compared with autumn and winter was found. Diestrus was shorter in summer than in the other seasons. Estrous behavior was always shown and characterized by rhythmic eversion of the vulvar labia (winking) with exhibition of the clitoris, urination, male receptivity and clapping, with sialorrhoea, neck and head extension, and back ears. Estrus was characterized by the ovulation of a larger follicle in spring and summer than in autumn and winter. The pattern of E2 and P4 plasma concentrations during the estrous cycle were similar to that reported for the mare, but without differences among the four seasons, so that a negligible effect of environmental conditions on ovarian E2 and P4 secretion was hypothesized, despite the larger diameter of the ovulating follicle in spring and summer.

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The survival rate was high, compared with rates reported after cesarean section, and short-term fertility rate was similar to those reported for mares that had a controlled vaginal delivery or cesarean section. Fetotomy performed by a skilled veterinarian on a nonviable fetus should be considered as a means of quick and safe correction of dystocia that does not necessarily impair short-term fertility in affected mares.

Today a great deal of research is focused on the development of new extenders that allow the refrigeration and maintenance of rabbit semen for a longer period of time. In this study, semen diluted with 3 different extenders (A, B, and C) and stored at two different temperatures (4°C and 38°C) were evaluated using both laboratory and in vivo tests. The best results were obtained with extender C (INRA 96) which, in the first 10 h of the test at 4°C, displayed about 80% higher motility compared to the other two extenders and preserved optimal seminal fluid motility for over 34 h after dilution. In the test at 38 °C, the motility of semen diluted with extender C was 52% in the fifth h vs 21% of the semens diluted with extenders A (Lepus) and B (Verdunnungsmischung). Another test involved artificial insemination (AI) of 1800 lactating does using refrigerated semen diluited with the extenders under study. The fertility rate and litter size obtained with semen diluted with extender C was higher (78.1% and 8.65, respectively) than those obtained with extenders A (71.2% and 8.15, respectively) and B (71.05% and 8.13, respectively) in both parallel and sequential tests. In conclusion, extender C offers greater vitality and motility to rabbit spermatozoa, thus higher fertility rates to rabbits does.