Antioxidants and Oxidants in Boar Spermatozoa and Their Surrounding Environment Are Associated with AMPK Activation during Liquid Storage

Oxyrase-Mediated Improvement in the Quality and Fertility of Crossbred Boar Spermatozoa During Liquid Storage

The present experiment was carried out to investigate the role of Oxyrase in preserving the in vitro quality, redox status and in vivo fertility of crossbred boar spermatozoa. A total of 24 ejaculates from 6 crossbred (n = 4 from each boar) boars were collected and extended in Beltsville Thawing Solution (BTS) in 1:2 ratio and divided into three aliquots. The first aliquot served as a control (without Oxyrase). Rest of the two aliquots were supplemented with 0.125 (T1) and 0.25 IU/mL Oxyrase (T2). Semen samples were preserved at 15°C for 5 days and kinematics of spermatozoa by CASA, semen quality parameters and oxidative stress status were evaluated at 0, 72 and 120 h of storage. The findings of studies revealed that supplementation of Oxyrase at 0.25 IU/mL resulted in higher (p < 0.05) total motility, progressive motility, plasma membrane integrity, acrosome integrity and functional integrity of plasma membrane at 72 and 120 h in comparison to the control group. Mitochondrial membrane potential (MMP) was higher (p < 0.05) at 72 and 120 h, whereas higher (p < 0.05) DNA integrity was observed at 120 h in T2. The lipid peroxidation (LPO) was lower (p < 0.05) and superoxide dismutase activity (SOD) and total antioxidant capacity (TAC) were higher (p < 0.05) in the T2 group at 120 h as compared to control. In vivo fertility trials indicated a higher (p < 0.05) litter size in T2 in comparison to other groups. The study concluded that the inclusion of Oxyrase at 0.25 IU/mL in the extender protects the crossbred boar spermatozoa against oxidative damage and improves the in vivo fertility.

Predicting Boar Sperm Survival during Liquid Storage Using Vibrational Spectroscopic Techniques

Artificial insemination (AI) plays a critical role in livestock reproduction, with semen quality being essential. In swine, AI primarily uses cool-stored semen adhering to industry standards assessed through routine analysis, yet fertility inconsistencies highlight the need for enhanced semen evaluation. Over 10-day storage at 17 °C, boar semen samples were analyzed for motility, morphology, sperm membrane integrity, apoptosis, and oxidative stress indicators. Additionally, machine learning tools were employed to explore the potential of Raman and near-infrared (NIR) spectroscopy in enhancing semen sample evaluation. Sperm motility and morphology gradually decreased during storage, with distinct groups categorized as "Good" or "Poor" survival semen according to motility on Day 7 of storage. Initially similar on Day 0 of semen collection, "Poor" samples revealed significantly lower total motility (21.69 ± 4.64% vs. 80.19 ± 1.42%), progressive motility (4.74 ± 1.71% vs. 39.73 ± 2.57%), and normal morphology (66.43 ± 2.60% vs. 87.91 ± 1.92%) than their "Good" counterparts by Day 7, using a computer-assisted sperm analyzer. Furthermore, "Poor" samples had higher levels of apoptotic cells, membrane damage, and intracellular reactive oxygen species on Day 0. Conversely, "Good" samples maintained higher total antioxidant capacity. Raman spectroscopy outperformed NIR, providing distinctive spectral profiles aligned with semen biochemical changes and enabling the prediction of semen survival during storage. Overall, the spectral profiles coupled with machine learning tools might assist in enhancing semen evaluation and prognosis.

Protective Effects of Betaine on Boar Sperm Quality during Liquid Storage and Transport

Boar semen is commonly used in artificial insemination (AI) for pig breeding, but its quality can be negatively affected by liquid preservation and transportation, leading to reduced fertility rates. Vibration and temperature fluctuations are critical factors that significantly impact semen quality during storage and transportation, influencing the success rate of AI procedures. Betaine, a naturally occurring compound known for its role in maintaining male fertility, demonstrates potential for improving the preservation and transportation of liquid-preserved boar sperm. The present study demonstrated that betaine supplementation in the semen extenders at 0.5 mg/mL had a significant protective effect on boar sperm motility during storage at 17 °C for 3 to 5 days. During road transportation, 2.5 mg/mL betaine showed significant protective effects on boar sperm progressive motility, while 0.4 mg/mL betaine notably improved boar sperm mitochondrial activity and antioxidant capacity, and reduced lipid peroxidation damage. Simulation models also demonstrated that betaine supplementation increased the proportion of sperm displaying progressive motility and possessing intact acrosomes, regardless of the storage temperature (17 °C or 25 °C), and effectively mitigated the damage caused by vibration at a speed of 200 r/min. Overall, supplementing liquid-preserved boar semen extenders with betaine shows promise in mitigating damage to sperm quality during storage and transportation.

Quality and fertilizing ability of frozen-thawed porcine sperm separated using a migration sedimentation method

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.

Post-Thaw Storage Temperature Influenced Boar Sperm Quality and Lifespan through Apoptosis and Lipid Peroxidation

Cryopreservation deteriorates boar sperm quality and lifespan, which restricts the use of artificial insemination with frozen-thawed boar semen in field conditions. The objective of this study was to test the effects of post-thaw storage time and temperature on boar sperm survival. Semen ejaculates from five Landrace boars (one ejaculate per boar) were collected and frozen following a 0.5 mL-straw protocol. Straws from the five boars were thawed and diluted 1:1 (v:v) in BTS. The frozen-thawed semen samples were aliquoted into three parts and respectively stored at 5 °C, 17 °C, and 37 °C for up to 6 h. At 0.5, 2, and 6 h of storage, sperm motility, viability, mitochondrial membrane potential, and intracellular reactive oxygen species (ROS) levels and apoptotic changes were measured. Antioxidant and oxidant levels were tested in boar sperm (SPZ) and their surrounding environment (SN) at each timepoint. The results showed significant effects of post-thaw storage time and temperature and an impact on boar sperm quality (total and progressive motility, VCL, viability, acrosome integrity), early and late sperm apoptotic changes, and changes in MDA levels in SPZ and SN. Compared to storage at 5 °C and 37 °C, frozen-thawed semen samples stored at 17 °C displayed better sperm quality, less apoptotic levels, and lower levels of SPZ MDA and SN MDA. Notably, post-thaw storage at 17 °C extended boar sperm lifespan up to 6 h without obvious reduction in sperm quality. In conclusion, storage of frozen-thawed boar semen at 17 °C preserves sperm quality for up to 6 h, which facilitates the use of cryopreserved boar semen for field artificial insemination.

Temperature Elevation during Semen Delivery Deteriorates Boar Sperm Quality by Promoting Apoptosis

Semen delivery practice is crucial to the efficiency of artificial insemination using high-quality boar sperm. The present study aimed to evaluate the effect of a common semen delivery method, a Styrofoam box, under elevated temperatures on boar sperm quality and functionality and to investigate the underlying molecular responses of sperm to the temperature rise. Three pooled semen samples from 10 Duroc boars (3 ejaculates per boar) were used in this study. Each pooled semen sample was divided into two aliquots. One aliquot was stored at a constant 17 °C as the control group. Another one was packaged in a well-sealed Styrofoam box and placed in an incubator at 37 °C for 24 h to simulate semen delivery on hot summer days and subsequently transferred to a refrigerator at 17 °C for 3 days. The semen temperature was continuously monitored. The semen temperature was 17 °C at 0 h of storage and reached 20 °C at 5 h, 30 °C at 14 h, and 37 °C at 24 h. For each time point, sperm quality and functionality, apoptotic changes, expression levels of phosphorylated AMPK, and heat shock proteins HSP70 and HSP90 were determined by CASA, flow cytometry, and Western blotting. The results showed that elevated temperature during delivery significantly deteriorated boar sperm quality and functionality after 14 h of delivery. Storage back to 17 °C did not recover sperm motility. An increased temperature during delivery apparently promoted the conversion of sperm early apoptosis to late apoptosis, showing a significant increase in the expression levels of Bax and Caspase 3. The levels of phosphorylated AMPK were greatly induced by the temperature rise to 20 °C during delivery but reduced thereafter. With the temperature elevation, expression levels of HSP70 and HSP90 were notably increased. Our results indicate that a temperature increase during semen delivery greatly damages sperm quality and functionality by promoting sperm apoptosis. HSP70 and HSP90 could participate in boar sperm resistance to temperature changes by being associated with AMPK activation and anti-apoptotic processes.