Improving reproductive technologies for the conservation of the European mink (Mustela lutreola)

The European mink (Mustela lutreola) is the most endangered mammal in Europe. The limited success of its breeding under captive conditions highlights the need to develop appropriate assisted reproduction techniques. In this work, sperm was collected by post-mortem epididymal flushing, by transrectal massage, and by electroejaculation in males administered (or not) oxytocin (0.2 IU i.m.). Morphometric analysis of the sperm heads was performed, comparing spermatozoa retrieved from the cauda epididymides with those collected from ejaculates. Artificial insemination was performed in eight females, and faecal assays of dihydrotestosterone, progestagens and estrogens were carried out. Oxytocin administration improved (P < 0.05) the electroejaculation process in terms of the time and number of electrical stimuli required (P < 0.05); it also improved sperm motility (P < 0.05). The heads of ejaculated sperm were larger than those of epididymal sperms (P < 0.05). Endocrine analyses revealed pseudopregnancy in the inseminated females, possibly due to the use of hCG to induce ovulation. A delay in the timing of insemination relative to ovulation might explain why true pregnancy was not achieved. The present results show that faecal estrogens are a useful marker for determining the most suitable moment to perform artificial insemination. The administration of oxytocin is recommended to improve the electroejaculation procedure.