A review of the use of antioxidants in bovine sperm preparation protocols

Improved pregnancy rate and sex ratio in fresh/frozen in vivo derived embryo transfer of Hanwoo (Bos taurus coreanae) cows

“…This suggests that the developmental capacity of embryos is more susceptible to damage caused by freezing. Slow freezing during cryopreservation leads to a decrease in viability due to the formation of ice crystals and the physical destruction of organelles caused by the presence of free water inside the cells [ 35 , 36 ]. As the embryo develops and progresses to the blastocyst stage, the size of the blastocyst cavity and the amount of water within it increases, thereby increasing the likelihood of damage during freezing.…”

Effect of In Vitro Addition of Melatonin and Glutathione on Seminal Parameters of Rams in Diluted Semen and after Thawing

“…However, the addition of MLT at 1 mM (G2) and GSH at 5 mM (G3), either alone or in combination (G4), did not improve SPZ parameters, with only 40% and 60% being found for IM and TM (CASA), respectively. The use of antioxidants such as MLT and GSH to prevent oxidative stress during semen storage has been studied in different species but with contradictory results [ 8 , 44 ]. Some authors reported that the addition of melatonin [ 12 , 46 ] and GSH [ 13 , 18 , 19 ] improves semen quality and motility, while others did not [ 47 , 48 ].…”

“…At the physiological level, ROS are important for normal SPZ function; however, in situations of oxidative stress, high levels of these compounds compromise sperm viability, causing morphological and functional damage through the oxidation of lipids, proteins, sugars, and DNA [ 5 , 6 , 7 ]. Procedures such as freezing, thawing, centrifugation, and incubation are thought to produce significant amounts of ROS, with a negative impact on sperm quality parameters and reproductive competence [ 8 ]. It is believed that hydrogen peroxide (H 2 O 2 ) is the main ROS responsible for these forms of damage, resulting in decreased SPZ motility and viability and changes that hinder sperm fusion with the oocyte during fertilization [ 7 ].…”

“…The maintenance of these proteins enhances the SPZ energy metabolism required for motility, viability, and membrane integrity. In this regard, several studies have described the protective role of GSH during storage and sperm cryopreservation in humans [ 17 ], equines [ 20 , 21 ], dogs [ 22 ], pigs [ 23 ], cattle [ 8 , 24 ], goats [ 13 , 18 ], and sheep [ 19 ].…”

“…Some studies [ 8 , 35 ] have provided preliminary evidence of the positive effects of antioxidants on sperm physiology and fertility in humans and domestic animals by evaluating the effects on DNA integrity, sperm motility, the lipid peroxidation of sperm membranes, sperm-oocyte fusion, sperm capacitation, cAMP metabolism, and the reduction in bovine sperm motility under H 2 O 2 -induced oxidative stress. One of the objectives of this manuscript was to investigate, in native Portuguese breed rams, the effects of adding the antioxidants GSH and MLT and their combination to the semen extender on the parameters of kinetic motility and the number of live and normal SPZ (in both diluted and thawed semen).…”