Sperm cryopreservation in alpacas:Other points of view

Abstract Background: This review addresses the points that have triggered a series of studies and methodologies trying to obtain alpaca sperm that are capable of maintaining their integrity, viability, and fertility after the freezing-thawing process. Unlike other species of zootechnical interest, it was considered to present this topic in a different way, exploring challenges that researchers faced when trying to freeze alpaca semen. Methods: Considering the fact that there are several methods for collecting semen or sperm cells from alpacas, the effects of seminal plasma during preservation were primarily considered. Different methods to reduce seminal viscosity were addressed, including those based on mechanical or biochemical tools. Paths to obtaining acceptable viability and fertilizing capacity of the sperm cells were many and diverse. Extenders used for raw, cooled or frozen sperm cells in alpacas were also included. Results: To date, alpaca sperm conservation techniques have not been as successful as they were in other domestic species. In the particular case of cryopreservation, the best in vitro results obtained after thawing were not necessarily reflected in fertility after artificial insemination. To enable this technique, not only will cryopreservation techniques need to be improved, but it is also necessary to evaluate the number of sperm cells per dose, the site of deposition of the seminal material, the presence of seminal plasma at the moment of seeding, the time of insemination, among other factors. Conclusions: It can be said that there are currently several lines of research that are contributing valuable knowledge on the sperm physiology and cryopreservation applied on alpaca. It is clear that there is still plenty of opportunity for research in this interesting species.