Characteristics of Okinawan Native Agu Pig Spermatozoa After Addition of Low-Density Lipoprotein to Freezing Extender

Abstract

Abstract. Technical refinement of boar sperm cryopreservation is indispensable for effective breeding of the rare Okinawan native pig, the Agu. The objective of the present study was to determine whether addition of low-density lipoprotein (LDL) extracted from hen egg yolk to the freezing extender improves the characteristics of cryopreserved Agu spermatozoa. Ejaculated Agu sperm frozen in extender supplemented with 2, 4, 6, 8 or 10% LDL instead of egg yolk was thawed, and the post-thaw sperm characteristics were evaluated. Treatment with 4-8% LDL during cooling and freezing significantly increased the intracellular cholesterol content, as compared to that of sperm frozen in extender containing 20% egg yolk (P<0.05). Higher potential resistance to cell damage from cryoinjury was also observed in sperm frozen in extender supplemented with LDL: the integrities of plasmalemma and DNA, mitochondrial activity and proteolytic activity of the acrosomal content in the post-thaw sperm were superior to those of sperm that were not treated with LDL. Moreover, the percentages of total motile sperm and the extent of rapid progressive motility at 1 and 3 h after incubation were markedly higher in sperm treated with 4 or 6% LDL, and these sperm also had more ATP. However, LDL did not inhibit in vitro sperm penetrability, even though the cholesterol content of post-thaw sperm was higher after treatment with LDL. These findings indicate that addition of 4-6% LDL instead of egg yolk to the freezing extender improves the post-thaw characteristics of Agu sperm by protecting sperm against cold shock damage during cryopreservation. Key words: Boar spermatozoa, Cell damage, Cryopreservation, Low-density lipoproteins (LDL) (J. Reprod. Dev. 55: [558][559][560][561][562][563][564][565] 2009) ecently, the male reproductive ability (i.e., semen volume, sperm quality and sperm concentration) of the Okinawan native pig, the Agu, has markedly decreased because of repeated inbreeding within a minority of the closed population for the past 20 years, which has resulted in a marked reduction in reproductive efficiency under natural mating conditions. Consequently, longterm preservation and storage of Agu sperm for artificial insemination (AI) has become a subject of interest because it permits insemination of a large number of females in a short period of time, avoids transmission of disease and conserves valuable germplasm stocks. However, the poor post-thaw survival of boar sperm has limited the success of AI with frozen sperm and has prevented its widespread acceptance in commercial breeding [1,2].Boar sperm are extremely sensitive to the damaging effects of cold shock [3]. The susceptibility of sperm to cryopreservation differs across species: rooster, human, monkey, rabbit and dog sperm are more resistant to cold shock than bull, ram, horse and boar sperm [3][4][5][6]. According to previous reports [4,6], the ratio of proteins to phospholipids in the plasma membrane is lowest in rooster sperm, at 0.46, moderate in bull and stallion sperm ...

Fertilization capacity with rainbow trout DNA-damaged sperm and embryo developmental success

“…These data reflect the importance of studying the consequences of fertilizing with DNA-modified sperm. DNA strand breaks and base oxidization are promoted during freezing-thawing, as has been described in several species (Baumber et al 2003, Pérez-Cerezales et al 2009, Thomson et al 2009, Yamauchi et al 2009). Thus, the use of cryopreserved sperm combined with other ARTs could increase the risk of undesirable modified genetic material being transmitted to the offspring.…”

Breed Characteristics of Indigenous Pigs in Okinawa :Growth Performance, Carcass Traits and Meat Quality

“…The body size of the Agu pig is similar to that of mediumsized Chinese breeds such as Jinhua pigs (TOUMA and OIKAWA, 2017). Previous studies have revealed that Agu pigs are characterized by poor fertility in terms of litter size (TOUMA and OIKAWA, 2017), and poor male reproductive ability attributed to sperm quality and concentration (YAMAUCHI et al, 2009). …”

The role of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in comparison with whole egg yolk for sperm cryopreservation in rhesus monkeys

“…The addition of LDL instead of egg yolk has been shown to increase cholesterol content of post-thaw sperm in boars. 10 Therefore, the protective role of LDL in rhesus monkey sperm cryopreservation could also be due to a higher cholesterol content provided by LDL.…”

“…11 Samples were allowed to liquefy for 30 min before processing. Sperm suspensions were washed twice with a modified Tyrode's medium supplemented with 3 mg ml 21 bovine serum albumin (TL-BSA, 290 mOsmol kg 21 ) at 300 g for 10 min, and resuspended to 2310 8 cells ml 21 of total motile sperm (sperm density3 initial motility) with TEST solution (43.25 g TES, 10.265 g Tris, 10 g glucose in one liter distilled water, pH 7.4, 350 mOsmol kg 21 ) before subject to various treatments. Sperm were frozen at a final concentration of 5310 7 cells ml 21 .…”

“…9 In addition, some egg yolk components are known to interfere with laboratory biochemical assays and metabolic parameters. 10 In fact, the majority of recent studies indicate that the improvement in post-thaw viability with LDL is due to the removal of these negative effects in the whole egg yolk ( Table 1).…”