Use of phosphatidylcholine in Tris-based extender with or without egg yolk to freeze Bapedi ram semen

Abstract

Traditionally, egg yolk is a protective agent that is used to freeze semen in various species. However, the addition of egg yolk in extender risks the introduction of disease. Therefore, an alternative cryoprotective agent should be found to preserve ram semen. The aim of this study was to evaluate the effect of phosphatidylcholine (PC) as a protective agent in extender with or without egg yolk on semen characteristics and acrosome integrity of frozen then thawed Bapedi ram semen. Semen was collected from four mature Bapedi rams, in the Agricultural Research Council (ARC) Germplasm Conservation Programme, using an artificial vagina. Following collection, semen samples were randomly diluted into Tris-based extender (1: 2), with and without egg yolk, and supplemented with four concentrations of PC liposome (0 mg/ml), 0.25 mg/ml, 0.5 mg/ml and 0.75 mg/ml). Supplementation of PC liposome in extender with or without egg yolk did not improve the semen total motility (TM), progressive motility (PM) and rapid motility (RM) rate. The sperm cell membrane integrity in extender with or without egg yolk was not influenced by the supplementation of PC liposome after thawing (P >0.05). The addition of PC liposome to Tris-based extender with egg yolk had a similar result to control (Tris-based extender with egg yolk) on sperm cell acrosome integrity. In conclusion, supplementation of PC liposome to Tris-based extender without egg yolk had lower sperm cell viability and motility rates compared with the extender with egg yolk, regardless of concentration.Keywords: acrosome, cryoprotectant, liposome, membrane, motility

Semen characteristics of Bapedi sheep during the autumn breeding season

“…Following semen collection, semen volume was measured by reading measurements on the calibrated collecting tubes and recorded in millilitres (ml) (Mafolo, 2018). The colour of the semen was observed and categorised as clear, cloudy, milky, creamy, or thick creamy as described by Mohlomi (2015).…”

“…The fat-tailed Bapedi sheep were rst established in Sekhukhuneland, and are currently predominant in the Limpopo Province of South Africa (Almeida, 2011). The Bapedi sheep breeds are multicoloured with a white coat and brown head being more dominant than black and white patterns on the body (Mafolo, 2018). The population size and the genetic diversity of Bapedi sheep are decreasing due to unsupervised breeding (Masenya et al, 2011).…”

An Update on South African Indigenous Sheep Breeds’ Extinction Status and Difficulties during Conservation Attempts: A Review

“…Oestrous synchronization and response: Advanced reproductive biotechnologies such as the oestrus synchronization have been used in South African indigenous sheep (Table 7) [43]. Moreover, semen from these breeds has also been cryopreserved [44,45]. However, fewer data are available for artificial insemination using post-thawed semen.…”

The Current Trends in Using Nanoparticles, Liposomes, and Exosomes for Semen Cryopreservation

“…Moreover, liposomes can be loaded with lipid-related content (such as lecithin [110]) to improve the plasma membrane regeneration efficacy during the freeze-thaw process of ram spermatozoa. Liposomes were used as a cryoprotectant additives in several animal species including equine [111,112], buffalo [113], ovine [107,114,115], porcine [116], and bovine [117] with reported improvement in fertility after AI [118]. It has been proposed that liposomes with their contents of phospholipids (phosphatidylserine, dioleoylphosphatidylcholine, phosphatidylcholine, dipalmitoylphosphatidylcholine, and dimyristoylphosphocholine) and saturated and unsaturated fatty acids can fuse with the sperm plasma membrane and abate the damage to spermatozoa caused by the freeze-thaw process [119,120] (Figure 1).…”