Washing solution and centrifugation affect kinematics of cryopreserved boar semen

The Effect of κ-Carrageenan on Porcine Sperm Cryo-Survival

κ-Carrageenan is a sulfated polysaccharide from red seaweed with substantial antioxidant activities. This study aimed to investigate the effect of κ-Carrageenan treatment on frozen-thawed (FT) porcine semen quality. Therefore, the spermatozoa were diluted and cryopreserved in a freezing extender supplemented with 0 (control), 0.2, 0.4, 0.6, and 0.8 mg/mL κ-Carrageenan. Sperm kinematics were assessed immediately after thawing (AT) and post-incubation for 120 min. The viability, acrosome integrity, lipid peroxidation, mitochondrial membrane potential (MMP), and intracellular caspase activity were measured AT. The results indicated that 0.2 mg/mL κ-Carrageenan increased total and progressive motility AT and post-incubation for 120 min (p < 0.05). Moreover, the viable sperm percentage and MMP after 0.2 mg/mL treatment were higher than those after control and other κ-Carrageenan concentration treatments. The proportion of acrosome-intact spermatozoa was significantly higher after 0.2 and 0.4 mg/mL κ-Carrageenan treatment than that after control and other κ-Carrageenan concentration treatments. The intracellular caspase activity was not significantly different among the experimental groups. However, the MDA concentration after 0.2 mg/mL κ-Carrageenan treatment was lower (p < 0.05) than that after the control treatment. Taken together, adding κ-Carrageenan to the porcine semen freezing extender improved the FT sperm quality mainly by influencing membrane stability and protecting against oxidative stress.

Effects of Nobiletin supplementation on the freezing diluent on porcine sperm cryo-survival and subsequent in vitro embryo development

Nobiletin (NOB) is a bioflavonoid compound isolated from citrus fruit peels. The present study aimed to elucidate whether NOB facilitates the porcine sperm cryosurvival and embryo development after in vitro fertilization (IVF). To this end, spermatozoa were diluted and cryopreserved in a freezing extender supplemented with 0 (control), 50, 100, 150, and 200 μM Nobiletin. The kinematic patterns of frozen-thawed (FT) sperm were assessed after 30 and 90 min incubation using a Sperm Class Analyzer (SCA). Viability, acrosome integrity, and mitochondrial membrane potential (MMP) were measured by fluorescence microscopy 30 min after thawing using SYBR-14/PI, PSA/FITC, and R123/PI, respectively. Lipid peroxidation was determined using MDA assay after incubation for 90 min. The addition of 100 μM and 150 μM NOB to the extender significantly improved sperm progressive motility, and acrosome integrity compared to the control group (P < 0.05). The proportion of viable spermatozoa was significantly higher in the 150 μM NOB group. MDA levels were less in 50 μM and 150 μM NOB treated groups compared to the control. In addition, IVF with FT sperm was used to assess the embryo developmental competence. Treatment with 150 μM NOB before cryopreservation increased the cleavage and blastocyst formation rates compared to the control group. Furthermore, the relative expression of POU5F1 and AMPK, genes related to pluripotency and cell differentiation were significantly upregulated in embryos resulting from NOB-treated sperm compared to the control group. These results suggest that Nobiletin is a functionally novel phytochemical to mitigate oxidative stress during the freezing-thawing of porcine spermatozoa as reflected by improved FT sperm quality and IVF outcome.

Sperm cryopreservation in Windsnyer boars; principles, technique, and updated outcomes

The domestic pig breeds are in danger of extinction whereas the erosion of their gene pool is a serious concern because they significantly contribute to the rich biodiversity. Overall aim of this study was to determine the protocol for preserving the semen of the Windsnyer boars for conservation. A total of 18 ejaculates (6 replications/boar) were collected from three Windsnyer boars of proven fertility with the use of hand-gloved approach method, twice per week. Boars semen were pooled and extended with Beltsville Thawing Solution [(BTS) IMV Technologies, France], held at 18°C for 3 hours and centrifuged. The sperm pellet was re-suspended with Fraction A (20% egg yolk + BTS) and cooled at 5°C for 1 hour. Following cooling, semen was divided and diluted into different cryoprotectants (ethylene glycol, glycerol, propanediol, ethylene glycol + glycerol + propanediol) at equal contribution to make the total concentrations [4, 8, 12 and 16% and the 0% (control; without cryoprotectant)] and loaded into 0.25 mL straws. Two cryopreservation methods (liquid nitrogen vapour and controlled rated) were used to cryopreserve the semen straws. Semen straws were thawed at different temperatures (5, 18, 37 and 40°C) and evaluated for sperm motility, viability, and morphology traits. Post-thawed sperm total motility (36.0±5.3) and live normal sperm (49.5±8.3) percentages were recorded to be higher in the treatment supplemented with 16% glycerol (P<0.05). The highest sperm total motility percentage was recorded at 40°C (26.8±3.2) thawing temperature for liquid nitrogen vapour treatment (P<0.05). In conclusion, 16% glycerol was found to be the suitable cryoprotectant concentration for semen cryopreserved with liquid nitrogen vapour method and thawed at 40°C.

Quercetin improves the apoptotic index and oxidative stress in post-thaw dog sperm

Freeze storage of ejaculated sperms is a crucial technique for the semen preservation of valuable pet animals such as dogs. The current study was conducted to investigate if quercetin (QRN) may ameliorate apoptosis and oxidative stress in post-thaw dog sperm. Herein, we evaluated the post-thaw apoptosis and oxidative stress after treatment with QRN (control, 25, 50, and 100 μM) in the freezing of dog semen. Reactive oxygen species levels were significantly affected (p < 0.05) between the various concentrations of QRN and the control (17.56 ± 1.02, 7.54 ± 0.48, 5.66 ± 0.80, and 10.41 ± 0.69), respectively. The apoptosis index was 9.1 ± 1.34, 6.66 ± 0.58, 6.77 ± 0.66, and 5.38 ± 0.86 in the control, and 25, 50, and 100 μM QRN treatment groups, respectively (p < 0.05). The effects of ameliorated cryo-induced damage by QRN on post-thaw sperm quality were also observed through improved structural and functional tests. Sperm treated with 50 μM QRN showed significantly higher motility (51.8 ± 2.1% vs. 43.1 ± 1.4%, P < 0.05), survival rates (46.9 ± 0.7% vs. 43.9 ± 0.4%, P < 0.05), and mucus penetration than control group, respectively. Results also indicated that higher concentrations of QRN (100 μM) were not effective on sperm quality and parameters when compared with the medium levels (50 μM). In conclusion, supplementation of freezing buffer with 50 μM QRN reduced oxidative damage and improved the quality of post-thaw dog sperm.