Cryoprotectants & Cryopreservation of Equine Semen: A Review of Industry Cryoprotectants and the Effects of Cryopreservation on Equine Semen Membranes

Abstract

Equine semen is a one of the most difficult in the industry to cryopreserve efficiently without causing damage to the membrane or apoptosis. This review consists of an in depth analysis of current cryoprotectant classes, membrane damage issues, reactive oxygen species generation, and apoptosis-all of which are exacerbated by cryopreservation.

Markers for Sperm Freezability and Relevance of Transcriptome Studies in Semen Cryopreservation: A Review

“…Spermatozoa comprise several compartments enclosed within the acrosome, plasma membrane, and mitochondrial membranes, which act as physiological barriers that must remain intact to permit cell viability, particularly after cryopreservation [1,2,6,10]. In recent years, several luorescent probes have shown that the cryopreservation process compromises the sperm plasma membrane integrity (PMI), resulting in reduced fertilizing capacity of postthaw semen [3][4][5][23][24][25][26][27][28][29].…”

“…Cryopreservation of semen allows the preservation of good genetic resources and the protection of endangered species [1][2][3][4][5]. While a great deal of eforts has been done over the last several years to improve the semen cryopreservation technology, efective cryosurvival of spermatozoa from various animal species, including the boar and stallion, still remains elusive and a cryobiological enigma [1].…”

“…Cryo-induced oxidative stress is associated with excess production of reactive oxygen species (ROS), resulting in biochemical and physical damage to the sperm membrane structures and subsequently leading to reduced fertilizing ability of spermatozoa [4][5][6]. In the artiicial insemination (AI) industry, there is a need to optimize the selection strategy for individuals with good freezability, so as to incorporate this information in the breeding program to improve the fertility of post-thaw semen [2,3,7]. Moreover, selection of animals with good semen freezability for cryopreservation and AI is a crucial step to improve the fertility levels of frozen-thawed semen [9,10].…”

“…Moreover, selection of animals with good semen freezability for cryopreservation and AI is a crucial step to improve the fertility levels of frozen-thawed semen [9,10]. Furthermore, in some animal species, despite satisfactory results of fertility in liquid-stored semen, frozen-thawed semen does not give acceptable fertility results in AI practice in the commercial industry [2,3,9].…”

“…Accumulating evidence has indicated that inherent male variability in semen freezability is one of the factors responsible for marked diferences in the sperm cryosurvival [2,5,[7][8][9][10]. With regard to boar semen, studies have reported that diferences in sperm freezability might be due to a genetic origin [7,8].…”