Cryosurvival and In Vitro Fertilizing Capacity Postthaw Is Improved When Boar Spermatozoa Are Frozen in the Presence of Seminal Plasma From Good Freezer Boars

Abstract

The study evaluated the protective effect of seminal plasma (SP) added to freezing extender against cryopreservation injuries to boar spermatozoa. Pooled sperm-rich fractions collected from 9 fertile boars were frozen in 0.5-mL straws after being extended in a conventional freezing extender either alone or supplemented with 5% of SPs (SP1-SP4) collected from the sperm-rich fractions (diluted 1:1, vol/vol, in Beltsville Thawing Solution extender) from 4 boars (1-4) with known sperm cryosurvival (poor, moderate, and good sperm freezers). Cryopreservation injuries were assessed in terms of postthaw sperm motility (assessed by computer-assisted sperm analysis), viability (plasma membrane and acrosome integrity assessed simultaneously by flow cytometry), membrane lipid peroxidation (malondialdehyde [MDA] production), and the ability of thawed spermatozoa to fertilize in vitro-matured homologous oocytes. The addition of SP from good sperm freezers (SP3 and SP4) improved (P , .01) the motility and viability of thawed spermatozoa without any influence on MDA production. Moreover, SP from good sperm freezers also increased (P , .05) the percentage of penetrated (SP3) and polyspermic oocytes (SP4) with respect to the control. Neither the total amount of SP proteins, protein profiles, nor antioxidant capacity of the different SPs were related to the various cryosurvival/fertilizing capacities of the processed spermatozoa.

Sperm surface changes and physiological consequences induced by sperm handling and storage

“…The presence of seminal plasma during freezing is generally considered to protect the sperm membrane but the effect is more pronounced in certain species. In the ram (Graham 1994, Maxwell et al 1999, Leahy et al 2010c) and boar (Suzuki et al 2002, Hernandez et al 2007a, Vadnais & Roberts 2007, inclusion of whole seminal plasma in the freezing regime results in the improvement of a whole host of functional parameters of spermatozoa upon thawing, including the ability to hold the sperm sample in a non-capacitated state.…”

“…The major determinants include donor animal (e.g. good vs poor freezing boars (Hernandez et al 2007a)), season (Leahy et al 2010c), sperm fraction utilised (e.g. sperm rich (Saravia et al 2009), as well as prior processing of seminal plasma (e.g.…”

Quality of boar spermatozoa from the sperm-peak portion of the ejaculate after simplified freezing in MiniFlatpacks compared to the remaining spermatozoa of the sperm-rich fraction

“…Thus it is not surprising that certain amounts of SP present in slightly cooled or frozen semen can improve sperm motility (Rodriguez-Martinez, 1991), maintain acrosome integrity (Maxwell et al, 1997), delay capacitation-like changes (Pursel et al, 1973), and increase the resistance to cold shock (Pursel et al, 1973;Watson, 2000) or oxidative stress (Roca et al, 2004;. Maintenance of these sperm attributes obviously lead to higher sperm longevity, cryosurvival and, subsequently, fertility (Zhu et al, 2000;Hernández et al, 2007;Okazaki et al, 2009;Garcia et al, 2010). However, spermatozoa are not exposed to a mixture of SP fractions in vivo, as it occurs when an ejaculate is collected (Rodriguez-Martinez et al, 2005), and SP has been considered detrimental for sperm viability if the spermatozoa are singly stored in SP (Kawano et al, 2004).…”

Antioxidant Effects of Seminal Plasma on Cellular Morphological Viability of Swine Semen Post-Cryopreservation

“…Additionally, dead spermatozoa contribute towards the cumulative ROS levels, exacerbating the process of damage to viable sperm [16][17][18]. Furthermore, controversial results may hamper the practical use of SP on cryopreserved semen i.e., while some studies support beneficial effects of SP [19][20][21][22], others are confounded by intricate experimental designs [23][24][25] or even detrimental effects have been reported [26,27]. It is plausible to infer that the variation in SP antioxidant activity between boars may carry a significant weight since adding SP from good freezers to frozen-thawed semen with mediocre performance resulted in improved viability and membrane integrity [23].…”

“…Altogether, these enzymes are considered the main barrier as per sperm antioxidant protection [14] and their concentrations may not only have an effect at cryopreservation but on the overall boar fertilizing ability [3,29]. Despite some discouraging results of SP as an additive for cryopreservation, literature supporting its beneficial effects is outweighing e.g., protection against cold shock, reduction of cryocapacitation [5,6,14,15] and, improvement on the percentage of viability, motility and integrity of both plasma and acrosome membrane [23,30,31]. Recently, a seasonal variation of antioxidant activity in fluids from the vesicular glands has been reported and intriguingly, this effect is independent from the antioxidant enzyme activity of epididymal fluids [32].…”