Crude Garden Cress Seed Oil (Lepidium sativum Linn.) Enhances Post-Thawed Boar Sperm Quality

This study aimed to examine the effects of crude garden cress seed oil (CGCSO) on frozen-thawed boar sperm qualities. Semen ejaculates (n = 12) were collected and further divided into six equal aliquots based on CGCSO concentrations (0, 0.5, 1, 1.5, 2, and 2.5% v/v) in the freezing extender. Semen samples were processed and cryopreserved utilizing the traditional liquid nitrogen vapor technique. Subsequently, semen samples were thawed in a thermos with warm water at 50 °C for 12 s and evaluated for sperm morphology using scanning electron microscopy, sperm motility using a CASA, sperm viability, acrosome integrity, mitochondrial function, MDA level, total antioxidant capacity (TAC), glutathione peroxidase (GSH-Px), and catalase (CAT) activity. The results indicated that 1% CGCSO resulted in superior post-thaw sperm characteristics, including enhanced sperm morphology, motility, viability, acrosome integrity, and mitochondrial function. Particularly, the total motile sperm increased by 16.5%, progressive motile sperm increased by 13.0%, viability improved by 15.1%, acrosome integrity increased by 14%, and mitochondrial function improved by 14.1% compared to the control group. CGCSO treatment at 1% and 1.5% exhibited the lowest level of MDA (45.73 ± 11.2 and 45.73 ± 11.3 µmol/L, respectively) compared to the other groups. The CGCSO-supplemented groups showed higher values of TAC, GSH-Px, and CAT than the control group but not significantly.

Boar semen cryopreservation: State of the art, and international trade vision

Biosecurity is a major concern in the global pig production. The separation in time of semen collection, processing and insemination in the pig farm is a few days for chilled semen but it can be indefinite when using cryopreserved semen. Field fertility results of boar cryopreserved semen are close to chilled semen, which makes it a valuable resource for the establishment of semen genebanks, long-distance semen trade, and the implementation of other technologies such as the sex-sorted semen. But cryopreserved semen is far from being routine in pig farms. The most recent research efforts to facilitate its implementation include the use of additives before freezing, or in the thawing extender. Long-term preserved semen trade is a biosecurity challenge. To harmonize international trade of germplasm, the World Organization of Animal Health (WOAH) established a regulatory framework for all member countries. The present paper aims to review the latest advances of boar semen cryopreservation with special focus on the benefits of its inclusion as a routine tool in the pig industry. We also review recently reported field fertility results of cryopreserved semen, its international trade compared to chilled semen, and the regulatory framework involved. Boar cryopreserved semen is a valuable tool to control biosecurity risk, implement other technologies, and facilitate international trade. Research already demonstrated good field fertility results, but it still represents less than 0.1 % of the international trade. As boar cryopreserved semen gets closer to implementation, the correspondent authorities are reviewing the trade rules.

Camellia oil with its rich in fatty acids enhances post-thawed boar sperm quality

BACKGROUND

Boar sperm are highly susceptible to specific conditions during cryopreservation, leading to a significant decrease in their fertilizing potential due to damage to their membranes. Camellia oil, known for its fatty acids with antioxidant and biological properties, has not been previously explored for the cryopreservation of boar semen. This study aimed to examine the effects of camellia oil on post-thawed boar sperm quality. Boar semen ejaculates (n = 9) were collected and divided into six equal aliquots based on camellia oil concentrations (0, 0.5, 1, 1.5, 2 and 2.5% v/v) in the freezing extender. Semen samples were processed and cryopreserved using the liquid nitrogen vapor method. Thereafter, frozen semen samples were thawed at 50 °C for 12 s and evaluated for sperm morphology by scanning electron microscope, sperm motility using a computer-assisted sperm analyzer, sperm viability, acrosome integrity, mitochondrial function, MDA level and total antioxidant capacity.

RESULTS

The results demonstrated that the supplementation of 1.5% (v/v) camellia oil showed superior post-thaw sperm qualities such as improved sperm morphology, motility, acrosome integrity and mitochondrial function by 14.3%, 14.3% and 11.7%, respectively, when compared to the control group. Camellia oil at a concentration of 1.5% (v/v) showed the lowest level of MDA (18.3 ± 2.1 µmol/L) compared to the other groups.

CONCLUSIONS

In conclusion, adding 1.5% (v/v) camellia oil in the freezing extender reduced the oxidative damage associated with cryopreservation and resulted in a higher post-thawed sperm quality.

Palm Kernel Meal Protein Hydrolysates Enhance Post-Thawed Boar Sperm Quality

Boar sperm is sensitive to particular conditions during cryopreservation, resulting in an extreme reduction in fertilizing ability due to damage to the sperm membranes. PKMPH contains bioactive peptides that have antioxidant and antimicrobial activities. There is no information on the use of palm-kernel-meal-derived bioactive peptides for boar semen cryopreservation. This study aimed to examine the effects of bioactive peptides from PKMPH on post-thawed boar sperm quality. Boar semen ejaculates (n = 17) were collected and divided into six equal aliquots based on PKMPH concentrations (0, 1.25, 2.5, 5, 10, and 15 µg/mL) in a freezing extender. Semen samples were processed and cryopreserved using the liquid nitrogen vapor method. Thereafter, the frozen semen samples were thawed at 50 °C for 12 s and evaluated for sperm motility using a computer-assisted sperm analyzer and for sperm viability, acrosome integrity, mitochondrial function, and lipid peroxidation by measuring the level of malondialdehyde (MDA). The results demonstrate that the supplementation of PKMPH with 2.5 µg/mL afforded superior post-thawed sperm qualities, such as increased total motility, viability, acrosome integrity, and mitochondrial function by 10.7%, 12.3%, 18.3%, and 12.7%, respectively, when compared to the control group. PKMPH at a concentration of 2.5 µg/mL showed the lowest level of MDA (40.6 ± 2.0 µMol/L) compared to the other groups. In conclusion, adding PKMPH peptides at 2.5 µg/mL to the freezing extender reduced the oxidative damage associated with cryopreservation and resulted in higher post-thawed sperm quality.

The Beneficial Effect of Resveratrol on the Quality of Frozen-Thawed Boar Sperm

This study aimed to determine the effect of resveratrol and its optimal concentration on the quality of frozen-thawed (FT) boar sperm. Semen ejaculates were obtained from 13 Duroc boars aged between 1.5 and 3 years. The sperm sample was separated into 7 groups based on the concentrations of resveratrol in the freezing extender, which were 0 (control), 25, 50, 75, 100, 125, and 250 µM, respectively. The sperm was frozen using liquid nitrogen vapor and thawed at 50 °C for 12 s. After thawing, total motility, progressive motility, viability, intact acrosomes, mitochondrial membrane potential and level of MDA were assessed. The supplementation of 50-100 µM resveratrol improved the sperm motility and viability of FT sperm in comparison to the control group (p < 0.05). Furthermore, the 50 µM resveratrol group was significantly more protective than the control group in terms of intact acrosome, mitochondrial membrane potential, and level of MDA (p < 0.05). Nonetheless, the detrimental effect of resveratrol was found at a concentration of 250 µM. In conclusion, the addition of 50-100 µM resveratrol to a freezing extender is the optimal concentration for enhancing the quality of cryopreserved boar sperm.

Gamma-oryzanol supplemented in extender enhances the quality of semen cryopreservation and alters proteomic profile in Thai swamp buffalo

Reactive oxygen species (ROS) exert an adverse effect on sperm quality during the freezing process. Gamma-oryzanol is an effective antioxidant and has the ability to inhibit lipoperoxidation in various cells. Therefore, this study aims to investigate the effect of gamma-oryzanol supplementation in extender on post-thawed motility and proteomic profiles of swamp buffalo spermatozoa. Each ejaculate of an individual bull was divided into four equal aliquots. Gamma-oryzanol was supplemented at 0 (control), 0.1, 0.25, and 0.5 mM in tris-citrate egg yolk extender. The parameters of sperm motility were evaluated using computer assisted semen analyzer (CASA). The results showed that the progressive motility was significantly higher in 0.5 mM of gamma-oryzanol supplementation group when compared with the control group (p < 0.05), but no significant differences were observed among the treatments. In addition, a proteomic approach was applied to analyze the differentially expressed proteins in post-thawed sperm with or without gamma-oryzanol supplementation in extender. We confirmed that 2-phospho-d-glycerate hydro-lyase (ENO1), glutathione s-transferase mu 1 (GSTM1), phospholipid hydroperoxide glutathione peroxidase (GPX4), outer dense fiber protein 2 (ODF2), tektin-4 (TEKT4), tubulin beta-4B chain (TUBB4B), and ATP synthase subunit beta (ATP5B) were up-regulated in 0.5 mM of gamma-oryzanol supplementation group, which might be associated with the improved post-thawed motility observed in this treatment group. These results demonstrate the beneficial effect of gamma-oryzanol on post-thawed survival of swamp buffalo spermatozoa and help advance the understanding about molecular metabolism of sperm in this species.

Leukemia inhibitory factor and its receptor: expression and regulation in the porcine endometrium throughout the estrous cycle and pregnancy

Objective

Leukemia inhibitory factor (LIF) binds to a heterodimeric receptor composed of LIF receptor (LIFR) and glycoprotein 130 (GP130) to transmit signals into the cell. LIF plays an important role in reproduction by regulating immune response, decidualization, and implantation in several species. However, the expression of LIF and LIFR in the endometrium throughout the estrous cycle and pregnancy in pigs is not fully understood.

Methods

We analyzed the expression of LIF and LIFR in the endometrium on days 0 (estrus), 3, 6, 9, 12, 15, and 18 of the estrous cycle, and days 12, 15, 30, 60, 90, and 114 of pregnancy, in conceptuses on days 12 and 15, and in chorioallantoic tissues on days 30, 60, 90, and 114 of pregnancy in pigs. We also determined the effects of estrogen and progesterone on the expression of LIF and LIFR in endometrial tissues.

Results

The expression of LIF increased in the endometrium during the late diestrus phase of the estrous cycle and during mid- to late- pregnancy, while the expression of LIFR increased during early pregnancy. The expression of LIF was induced by increasing doses of estrogen, whereas the expression of LIFR was induced by increasing doses of progesterone.

Conclusion

These results indicate that the expression of LIF and its receptor LIFR in the endometrium is regulated in a stage-specific manner during the estrous cycle and pregnancy, suggesting that LIF and its receptor signaling system may play critical roles in regulating endometrial function in pigs.

The Fertility of Frozen Boar Sperm When used for Artificial Insemination

One of the limits to practical use of frozen boar sperm involves the lowered fertility when used for artificial insemination. Years of studies have shown that 5-6 billion sperm (approximately 3 billion viable) used in single or multiple inseminations results in pregnancy rates most often between 60 and 70% and with litter sizes between nine and 10 pigs. Yet today, it is not uncommon for studies to report pregnancy rates from 70 to 85% and litter sizes with 11-12 pigs. While global statements about the incidence and reasons for higher fertility are not conclusive, incremental fertility improvements appear independently associated with use of a minimum number of viable sperm (1-2 billion), insemination timing that increases the probability that sperm will be present close to ovulation for groups of females, selection for boar sperm survival following cryopreservation, and modification of the freeze and thaw conditions using additives to protect sperm from oxidative damage. Studies show that techniques such as intrauterine and deep uterine insemination can provide an opportunity to reduce sperm numbers and that control of time of ovulation in groups of females can reduce the need for multiple inseminations and improve the chance for AI close to ovulation. However, optimal and consistent fertility with cryopreserved boar sperm may require a multifaceted approach that includes boar selection and screening, strategic use of additives during the freezing and thawing process, post-thaw evaluation of sperm and adjustments in sperm numbers for AI, assessment of female fertility and ovulation induction for single insemination. These sequenced procedures should be developed and incorporated into a quality control system for improved fertility when using minimal numbers of cryopreserved boar sperm.

Recent Advances in Boar Sperm Cryopreservation: State of the Art and Current Perspectives

While sperm cryopreservation is the best technology to store boar semen for long-term periods, only 1% of all artificial inseminations (AI) conducted worldwide are made using frozen-thawed boar sperm. With the emergence of long-term extenders for liquid storage, the use of cryopreserved sperm in routine AI is less required. However, banks of boar semen contain cryopreserved sperm and planning inseminations in AI centres may benefit from the use of frozen-thawed semen. Therefore, there is an interest in the use of this technology to preserve boar sperm. In this regard, although the first attempts to cryopreserve boar semen date back to the seventies and this technology is still considered as optimal, some relevant improvements have been made in the last decade. After giving a general picture about boar sperm cryodamage, the present review seeks to shed light on these recent cryopreservation advances. These contributions regard to protein markers for predicting ejaculate freezability, sperm selection prior to start cryopreservation procedures, additives to freezing and thawing extenders, relevance of the AI-technique and insemination-to-ovulation interval. In conclusion, most of these progresses have allowed counteracting better boar sperm cryodamage and are thus considered as forward steps for this storage method. It is also worth noting that, despite being lower than fresh/extended semen, reproductive performance outcomes following AI with frozen-thawed boar sperm are currently acceptable.

Effects of different dietary n-6/n-3 polyunsaturated fatty acid ratios on boar reproduction

BACKGROUND

N-3 and N-6 polyunsaturated fatty acids are widely used in reproduction, yet few studies have addressed the effects of dietary n-6/n-3 ratios on boar reproduction. The present study aimed to determine the effects of different dietary n-6/n-3 ratios on the reproductive performance of breeding boars. Thirty-two boars with body weights of 15.0 ± 1.4 kg were divided into four treatments (C, T1, T2, T3) and fed diets with different n-6/n-3 fatty acid ratios (29.06:1, 20.07:1, 1:1, 1:17.96, respectively) for 174 days.

RESULTS

The highest testis index was observed for treatment T2. Sperm density and total sperm number per ejaculate in the T2 treatment were significantly higher than those in all other treatments, whereas the sperm deformity rate was the lowest. Interestingly, the fatty acid compositions and ratios of sperm were consistent with dietary treatments. Acid phosphatase and fructose concentration of seminal plasma, and the total superoxide dismutase and glutathione peroxidase of sperm in T2 were higher than those in other treatments. The concentration of testosterone and prostaglandin E2 increased in boars fed on diets supplemented with fatty acids as compared with boars subjected to the C group treatment, reaching a peak at n-6/n-3 fatty acid ratios of 1:1. Furthermore, higher expression of Δ(6)-fatty acid desaturase and peroxisome proliferator activated receptor-α in spermatozoa of the T2 treatment were observed, indicating more vigorous metabolism and intensive hormonal regulation.

CONCLUSIONS

Our data suggest that the ideal n-6/n-3 ratio in the diet of breeding boars is 1:1, and proper balancing of n-6/n-3 fatty acids plays an important role in male reproduction.

The effect of Curcuma longa extracted (curcumin) on the quality of cryopreserved boar semen

The aim of this study was to determine the optimal concentration of curcumin needed for cryopreservation of boar semen. Semen samples (n = 9) were collected from nine Duroc boars which having proven fertility were used for routine artificial insemination. Semen samples were collected and divided into six groups (groups A-F) according to various concentrations of curcumin in freezing extender (i.e. 0, 0.125, 0.25, 0.50, 0.75 and 1.0 mmol/L, respectively). The semen was frozen by traditional liquid nitrogen vapor method and stored at -196°C in the liquid nitrogen tank. After storage, frozen semen samples were thawed at 50°C for 12 s and evaluated for progressive motility, viability and acrosome integrity. The present results indicated that the addition of curcumin at 0.25 (group C) or 0.50 mmol/L curcumin (group D) yielded the higher percentage of progressive motility (33.3 and 36.1%, respectively) (P < 0.001). A significantly higher percentage of acrosome integrity was found in groups B (29.7%), C (31.1%) and D (30.2%) than in the other groups (P < 0.01). However, there was no significant difference in percentage of viability among groups. In conclusion, addition to the freezing extender of curcumin during cryopreservation at a concentration of 0.25 or 0.50 mmol/L is the optimal concentration of curcumin for improving the quality (i.e. increased progressive motility and acrosome integrity) of cryopreserved boar semen.