Abstract
Simple SummaryFreezing dog semen is not always possible due to low quality sperm or poor survival during freezing. In order to make this assisted reproductive technique available to a larger number of dogs, this study investigated the benefit of selecting the best spermatozoa before freezing using single layer centrifugation (SLC). The results indicated that this technique was effective in separating spermatozoa according to their quality, although this resulted in losing some good quality spermatozoa. After thawing, spermatozoa centrifuged by SLC were of better quality than after standard centrifugation. However, spermatozoa from suboptimal quality semen did not survive freezing as well as spermatozoa from semen of optimal quality, even after SLC. Single layer centrifugation, therefore, makes it possible to obtain better quality spermatozoa after thawing but is not sufficient on its own to improve the inferior freezing ability of spermatozoa from suboptimal quality semen. So far, eighteen pups were born after insemination with SLC-selected frozen-thawed semen, proving that these selected spermatozoa remain fertile.This study evaluated how semen selection by single layer centrifugation (SLC) with Canicoll affects semen freezability in dogs. A total of eighteen ejaculates, collected from dogs with optimal and suboptimal semen quality (optimal: normal morphology (NM) ≥ 80%, n = 9; suboptimal: NM between 60 and 79%, n = 9), were divided into two aliquots and subjected to standard centrifugation or SLC before cryopreservation. Motility, NM, membrane integrity, mitochondrial membrane potential (MMP), and DNA integrity were improved in fresh samples after SLC, regardless of semen quality, but at the expense of some good quality spermatozoa. After thawing, NM and membrane integrity were improved in SLC-selected semen in both semen qualities. Interestingly, MMP was also higher but only in optimal quality semen. Still, spermatozoa from suboptimal quality semen did not survive freezing to the same extent as spermatozoa from optimal quality semen, even after selecting superior spermatozoa. Semen selection with Canicoll is, therefore, an effective technique to isolate a subpopulation of high-quality spermatozoa and obtain sperm samples of better quality after thawing, but is not sufficient to improve the intrinsic inferior freezability of suboptimal quality semen. So far, eighteen pups were born after insemination with SLC-selected frozen-thawed semen, proving that these selected spermatozoa remain fertile.
Highlights
In dogs, cryopreservation of semen has become a well-known assisted reproduction technique for breeders
The present study provides evidence that single layer centrifugation (SLC) with Canicoll prior to freezing improves some aspects of semen quality after thawing
SLC did not seem to select canine spermatozoa with an intact acrosome, to what was described in other studies [23,25], a loss of acrosomal integrity induced by the colloid has not been ruled out yet
Summary
Cryopreservation of semen has become a well-known assisted reproduction technique for breeders This technique allows the genetics of superior dogs to be preserved and exchanged with no restriction in time or distance [1–3]. Efforts should be made to improve semen cryopreservation from samples with suboptimal quality and/or samples with poor semen freezability In this respect, the selection of a subpopulation of superior spermatozoa could possibly be an approach to allow for better survival during cryopreservation. The selection of a subpopulation of superior spermatozoa could possibly be an approach to allow for better survival during cryopreservation This hypothesis is based on the fact that the presence of more senescent, damaged, non-motile, immature and/or dead spermatozoa in lower quality ejaculates might be deleterious to the survival of good quality spermatozoa, partly due to the production of reactive oxygen species (ROS) [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
