Slow and ultra-rapid freezing protocols for cryopreserving roe deer (Capreolus capreolus) epididymal sperm collected at different times of year

Single or repeated immunization against GnRH fails to completely abolish spermatogenesis in dwarf bucks (Capra hircus)

In both captive wildlife and production animals is important to develop strategies for population control. Immunization against GnRH is an easy and inexpensive immunocastration method that reduces the concentration of testosterone and decreases sperm quality. However, its effectiveness depends on the species and repetition of the treatment. This study aimed to compare the effectiveness of a single treatment (initial immunization plus a booster with Improvac) vs repeated treatment (six doses of Improvac) to inhibit testicular function and maintain the contraceptive status during long periods in bucks. Three Dwarf bucks (Capra hircus) received two doses of Improvac, the first on Week 0, and the booster 4 weeks later (single immunization, group SI) while three Dwarf bucks received one dose of Improvac every 6 months during 3 consecutive years (repeated immunization, group RI). The other three Dwarf bucks remained untreated (control bucks, group CON). Bucks from RI had a greater decrease in scrotal circumference, testosterone concentration, male odor intensity, and sperm quality than SI bucks. However, there were no differences between SI and CON bucks in any of the variables studied. Overall, repeated treatment of Improvac decreased the testicular function of Dwarf bucks, although did not produce complete infertility. However, the repetition of the treatment produced more intensive negative effects, indicating that the strength of the effects of Improvac is rapidly lost in bucks.

Recent Progress in Spermatology Contributing to the Knowledge and Conservation of Rare and Endangered Species

There is a remarkable diversity in the animal kingdom regarding mechanisms underlying the production, maturation, structure, and function of sperm cells. Spermatology studies contribute to the knowledge of species diversity and also provide information about individual or population fitness. Furthermore, this fundamental research is required before collected spermatozoa can be used for conservation breeding, including assisted reproduction and cryobanking. This article aims to (a) review the most recent knowledge on sperm morphology and function in wild animal species, (b) analyze how this knowledge can be used to save species in their natural habitat or ex situ, and (c) propose future scientific directions in wildlife spermatology that could positively impact animal conservation. Variations in sperm structure and performance within and between species have multiple origins and significance. This collective body of knowledge enables the design and implementation of conservation strategies and action plans that integrate several disciplines. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.