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We evaluated the quality and fertilizing ability of frozen–thawed porcine sperm that were selected using a commercially available device (MIGLIS, Menicon Life Science) consisting of three parts: an outer lid, an inner lid, and a tube. Firstly, to determine an adequate concentration of caffeine for separation, frozen–thawed sperm were incubated with different concentrations of caffeine (0, 1, 2.5, 5, and 10 mM) in a MIGLIS device. To determine the appropriate incubation time for separating sperm in the MIGLIS device, frozen–thawed sperm were incubated with 2.5 mM caffeine for 5, 10, 15, or 20 min. To evaluate the fertilization and embryo development of oocytes fertilized with frozen–thawed sperm separated into two regions (outer and inner) in the MIGLIS device, the separated sperm from the three boars was used to fertilize in vitro‐matured oocytes and cultured in vitro for 7 days. Sperm quality parameters of sperm collected from the inner tube after incubation with 2.5 mM caffeine were superior to sperm incubated without caffeine. Moreover, sperm collected from the inner tube after incubation for 10 min had a higher progressive motility. The rate of blastocyst produced from spermatozoa collected from the inner tube after incubation with 2.5 mM caffeine for 10 min significantly increased compared to that produced from spermatozoa from the outer tube, regardless of the boar. In conclusion, sperm sorting using the MIGLIS device may be useful for separating high‐quality sperm after incubation with 2.5 mM caffeine for 10 min to improve blastocyst formation. [ABSTRACT FROM AUTHOR]

Sterilization of the culture medium using ultraviolet (UV)‐C reduces the potential adverse effects of microorganisms and allows for long‐term use. In the present study, we investigated the effects of a medium directly irradiated with UV‐C prior to in vitro culture on the development and quality of porcine in vitro‐fertilized embryos and the free amino acid composition of the culture media. The culture media (porcine zygote medium [PZM‐5] and porcine blastocyst medium [PBM]) were irradiated with UV‐C at 228 and 260 nm for 1 and 3 days, respectively. Next, the culture media were irradiated with UV‐C at 228 nm for 3, 7, or 14 days. After in vitro fertilization, the embryos were cultured in the UV‐C‐irradiated media for 7 days. Free amino acid levels in culture media irradiated with 228 and 260 nm UV‐C for 3 days were analysed. The blastocyst formation rate of embryos cultured in media irradiated with 260 nm UV‐C for 3 days was significantly lower than that of embryos cultured in non‐irradiated control media. However, 228 nm UV‐C irradiation for up to 14 days did not affect blastocyst formation rates and quality in the resulting blastocysts. Moreover, 260 nm UV‐C irradiation significantly increased the taurine concentration in both culture media and decreased methionine concentration in the PBM. In conclusion, UV‐C irradiation at 228 nm before in vitro culture had no detrimental effects on embryonic development. However, 260 nm UV‐C irradiation decreased embryo development and altered the composition of free amino acids in the medium. [ABSTRACT FROM AUTHOR]

The oocyte maturation process requires a high supply of energy, which generates reactive oxygen species (ROS), adversely affecting oocyte and embryo development. Balancing ROS by antioxidant supplementation is essential for maintaining oocyte maturation and embryonic quality in vitro. This study aimed to evaluate the impact of four antioxidants: β‐mercaptoethanol (β‐ME), chlorogenic acid (CGA), curcumin and sericin, when applied individually or in combinations, during oocyte maturation on development of porcine oocytes. Cumulus–oocyte complexes were collected, cultured in maturation medium supplemented with antioxidants for 44 hr and subsequently subjected to in vitro fertilization (IVF) and culture for 7 days. Combining all four (β‐ME + CGA + curcumin + sericin) or three (β‐ME + CGA + curcumin) antioxidants increased blastocyst formation rates. However, sericin supplementation alone, or in combination with β‐ME or CGA, failed to improve blastocyst formation rates. The total cell numbers of blastocysts from the group supplemented with three antioxidants (β‐ME + CGA + curcumin) were significantly higher than those from the other groups, except for the curcumin‐supplement group. There were no differences in the maturation rates and proportions of oocytes with fragmented DNA between the antioxidant‐supplemented and the non‐supplemented control groups. In conclusion, supplementation with three antioxidants (β‐ME + CGA + curcumin) during the maturation culture enhanced blastocyst formation and improved blastocyst quality. [ABSTRACT FROM AUTHOR]

Although the interspecies hybridization of bovids, such as cattle–yak (Bos taurus × Bos grunniens), has heterosis benefits, the infertility of hybrid males affects the maintenance of dominant traits in subsequent generations. To achieve reproductive capacity, male germ cell development requires coordinated changes in gene expression, including DNA methylation and generalized histone modifications. Although gene expression‐related mechanisms underlying hybrid male sterility have been investigated recently, information on the cell types and stage‐specific controls remains limited. Here, we used immunohistochemistry and image analyses to evaluate the 5‐methylcytosine (5MC) and acetyl‐histone H3 Lys9 (AcK9) expression in all spermatogonia and testicular somatic cell types to determine their roles in cattle–yak spermatogenesis. Testicular tissues from yak (1–3 years old) and backcrossed hybrids (2 years old) were used. In yak, the AcK9 expression levels increased in all cell types during maturation, but the 5MC expression levels did not change until reaching 3 years when they increased in all testicular cell types, except spermatogonia. Cattle–yak hybrids showed higher 5MC expression levels and different AcK9 expression levels in all cell types compared to the same‐aged yak. These results suggested that both gene modulation by AcK9 and constant levels of DNA methylation are required for spermatogenesis during maturation in yak. Therefore, inappropriate expression levels of both AcK9 and DNA methylation might be the major factors for disruption of normal germ cell development in cattle–yak. Additionally, various modulations occurred depending on the cell type. Further experiments are needed to identify the stage‐specific gene expression modulations in each cell type in yak and cattle–yak to potentially solve the infertility issue in crossbreeding. [ABSTRACT FROM AUTHOR]