Effect of addition of melatonin on liquid storage of ram semen at 4°C

Effects of melatonin on sperm quality, enzyme activity, antioxidant gene expression and fertility of cryopreserved bovine semen

Melatonin (MLT) has strong antioxidant capacity and can reduce the damage caused by oxidative stress in sperm, but there is still little content in the field we have studied. In this study, we are committed to scientific research on adding melatonin to Belgian blue bull semen diluent for cryopreservation. Different concentrations (0, 0.1, 0.3, 0.5 or 0.7 mg/mL) of MLT were added diluent. Sperm kinetic parameters, enzyme activity, antioxidant gene expression and fertility were analyzed after thawing. The results showed that MLT concentration of 0.3 mg/mL exerted positive effects on post-thaw kinetic parameters. Compared with other groups, 0.3 mg/mL MLT treated sperm acrosome and plasma membrane integrity, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels significantly increased. Meanwhile, the mRNA expression of antioxidant genes SOD2, CAT and GPx increased in the 0.3 mg/mL MLT treatment group, and the mRNA expression of apoptosis genes Caspase-3 and Bax were significantly reduced. In addition, in vitro fertilization (IVF) embryo cleavage, blastocyst rate and artificial insemination (AI) pregnancy rate were higher in 0.3 mg/mL MLT. Therefore, MLT showed cryoprotective capacity to the freezing diluent used for Belgian blue bull sperm during the process of freezing-thawing, and the optimal concentration of MLT for the frozen diluent was 0.3 mg/mL.

Effect of melatonin supplementation on sperm quality parameters and expression of antioxidant genes during cold storage of buck semen extenders

Background and Aim

Semen storage is an important reproductive method used in artificial livestock breeding. However, oxidative stress during storage reduces the quality of sperm. Melatonin supplementation in semen storage medium has not been well studied, but it has been shown to protect cells from oxidative stress. Therefore, this study aimed to determine the effect of melatonin supplementation on sperm quality parameters and antioxidant gene expression levels in semen extenders during cold storage.

Materials and Methods

Semen extenders with melatonin concentrations of 0 (control), 0.1, 0.2, and 0.3 mM were added as treatment. The treated semen was then stored at 5°C for 72 h using a cold storage method, and quality parameters, including percentage of progressive motility, membrane integrity, intact acrosome, and DNA integrity, were measured every 24 h. In addition, messenger ribonucleic acid abundance levels of glutathione peroxidase (GPx) and superoxide dismutase (SOD) genes were sampled after 0 and 72 h of cold storage.

Results

All observed sperm quality parameters decreased with increasing cold storage time; however, 0.2 mM melatonin demonstrated superior protection of sperm quality during cold storage. Gene expression analysis showed that GPx levels decreased significantly (p < 0.05) after 72 h in semen without melatonin but not in the melatonin-treated groups. A similar trend was also observed in SOD, indicating that exogenous antioxidants effectively protected the sperms.

Conclusion

Melatonin supplementation at 0.2 mM in semen extenders during cold storage maintains sperm quality parameters for up to 72 h because melatonin protects sperm from oxidative stress. These findings can be used to improve the semen storage protocol by combining semen extender and antioxidant.

Improving chilled and frozen buck sperm characteristics by adding melatonin and L-carnitine to the preservation medium

This study evaluated the effects of melatonin (MLT) and L-carnitine supplementation on sperm quality and antioxidant capacity during chilled and cryopreservation. Twenty-four ejaculates were collected from six Damascus bucks, 4 ejaculates each, from mid-September to mid-October 2022. The pooled semen from each collecting session was divided into 5 equal aliquots after being diluted (1:10) with Tris-citric acid egg yolk extender. The first aliquot served as a control (treatment-free). MLT was added to the second and third aliquots at low and high doses (LD: 4 and HD: 8 μL/mL) (v/v), respectively, while L-carnitine (LC) was added to the fourth and fifth aliquots at the same aforementioned doses. The aliquots were stored at 4°C for 48 h to assess sperm physical and morphological characteristics, alongside lipids peroxidase (LP) production and glutathione peroxidase (GPX) activity. The optimum doses of MLT and LC that showed potential for maintaining sperm characteristics throughout the chilled storage period were further investigated for protecting the spermatozoa after exposure to cryopreservation stress compared to the control. The results showed higher sperm motility (%) in the MLT-HD group, higher (p ≤ .05) sperm viability (%) in the MLT-LD, and both aliquots of LC at T24 hours of chilled preservation. Normal sperm (%) was higher (p ≤ .05) in both LC-LD and MLT-LD groups than other groups, while sperm acrosome integrity (%) was higher (p ≤ .05) in the LC-LD group. Morphological abnormalities (%) were improved (p ≤ .05) in all treated aliquots compared with control. The mean value of GPX activity was higher (p ≤ .05) in both MLT groups, while the concentration of LP increased (p ≤ .05) in the LC-HD or control groups. Furthermore, supplementing buck sperm medium with 4 μL/mL of MLT or LC improved (p < .05) the sperm characteristics and decreased (p < .05) DNA fragmentation index after thawing.

Evaluation of the effect of melatonin implantation in rams and eCG dose in ewes synchronized by a CIDR-eCG protocol on reproductive performance of Lacaune sheep breed during non-breeding season

Sustainable production of milk is favorable in dairy sheep industry, which necessitates year-round reproduction of rams and ewes even during non-breeding season. Hence, protocols facilitating reproduction of rams and ewes during non-breeding season are of importance for this purpose. Therefore, the present study was conducted to investigate the effect of melatonin implantation in rams and administration of 400 IU eCG (E400) versus 300 IU eCG (E300) in ewes on reproductive performance of Lacaune sheep breed during non-breeding season. Rams were allocated to two groups including untreated (control, CON; n = 36) and melatonin-treated (MEL; n = 37). A subset of rams from CON (n = 7) and MEL (n = 7) groups were used for assessment of scrotal circumference, kinematic and functional characteristics of sperm, total antioxidant capacity (TAC) of semen and circulating testosterone on Days 0 (the beginning of study) and 60 (60 days after melatonin implantation). Further, the study had a 2 × 2 factorial design with four experimental groups including 1) ewes treated with E300 and introduced to CON rams (E300CON; n = 17 rams and 172 ewes), 2) ewes treated with E300 and introduced to MEL rams (E300MEL; n = 18 rams and 177 ewes), 3) ewes treated with E400 and introduced to CON rams (E400CON; n = 19 rams and 192 ewes), and ewes treated with E400 and introduced to MEL rams (E400MEL; n = 19 rams and 190 ewes). Melatonin implantation improved scrotal circumference, concentration, progressive motility, velocity, mitochondrial membrane potential and viability of sperm, TAC of semen, concentration of testosterone and fertility of rams (P < 0.05). Besides, E400 compared with E300 enhanced synchronization of estrus and fertility in ewes (P < 0.05). In conclusion, melatonin implantation promoted reproductive performance in Lacaune rams, and increase in dose of eCG improved reproductive performance in Lacaune ewes.

Effect of In Vitro Addition of Melatonin and Glutathione on Seminal Parameters of Rams in Diluted Semen and after Thawing

The present study aimed to evaluate the effects of melatonin (MLT), glutathione (GSH), and their combination on ram semen quality after thawing. During eight weekly sessions, semen from three Merino rams was pooled, diluted with an egg-yolk-based semen extender, and divided into four groups: control, 1 mM MLT, 5 mM GSH, and 1 mM MLT + 5 mM GSH. Diluted semen was evaluated before and after the freezing process. The supplementation of diluted semen with GSH at 5 mM had a deleterious effect on total motility progressive (TPM), curvilinear velocity (VCL), straight-line velocity (VSL), average-path velocity (VAP), linearity (LIN), and straightness (STR) and increased slow spermatozoa (%). MLT at 1 mM also had a negative effect on TPM, VSL, and STR in diluted semen. In thawed semen, 1 mM MLT increased the TPM compared with the control group. VSL was lower in the 5 mM GSH group than in the 1 mM MLT group. Additionally, the combination of both antioxidants attenuated the negative effect of 5 mM GSH on TPM, VSL, and BCF. These results indicate that 5 mM GSH impairs or does not improve sperm kinetic parameters in either diluted or thawed semen. They also suggest that MLT combined with GSH plays a protective role against these effects.

Reducing oxidative stress by κ-carrageenan and C60HyFn: The post-thaw quality and antioxidant status of Azari water buffalo bull semen

Azeri water buffalo is a species of great interest due to the high quality of its products such as milk. Due to the decreasing trend of its number and risk of extinction in the future, our attention is directed towards ensuring the preservation of its genetic reserves by keeping its sperm. Using antioxidants in semen extender is one of the ways to reduce the detrimental effects of freezing process on post-thawed quality of spermatozoa. This study was conducted to determine the effect of κ-carrageenan (k-CRG) and C60HyFn supplemented semen extender on the quality of post-thawed Azari water buffalo spermatozoa. A total of 30 semen samples were obtained from three buffaloes using an artificial vagina (twice a week for five weeks = 10 replicates). The samples (n = 3) from each replicate were pooled and divided into equal aliquots to prepare 14 extender groups, including control (C), k-0.2, K-0.4, K-0.6, K-0.8 (containing 0.2, 0.4, 0.8 mg K-CRG/mL, respectively), C-0.1, C-0.2, C-0.4, C-0.8, C-1, C-5, C-10, C-20, and C-40 (containing 0.1, 0.2, 0.4, 0.6, 0.8, 1, 5, 10, 20, 40 μM C60HyFn, respectively), and then frozen. After thawing, motility and velocity parameters, plasma membrane integrity (PMI) and functionality (PMF), DNA damage, Hypo-osmotic swelling (HOS) test, malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase glutathione activities and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging were evaluated. In vivo fertility was compared between k-0.6, C-1 and control groups. 60 buffalo were inseminated 24 h after the onset of estrus. The diagnosis of pregnancy was performed rectally at least 60 days after fertilization. Total and progressive motility and velocity parameters were improved by k-0.4, k-0.6, k-0.8, C-0.4, C-0.8, C-1, C-5, and C-10 groups) compared to the other groups. Plasma membranes integrity and PMF were improved by k-0.4, k-0.6, C-0.4, C-0.8, C-1, C-5, and C-10 groups compared to other groups, while in terms of sperm DNA damage K-0.4, K-0.6, K-0.8, C-0.2, C-0.4, C-0.8, C-1, C-5, and C-10 groups showed better results compared to the control group. The evidence also showed that k- 0.4, k-0.6, k-0.8, C-0.4, C-0.8, C-1, C-5, and C-10 groups could improve TAC, and decrease MDA levels. Also, k-0.4, k-0.6, k-0.8, C-0.2, C-0.4, C-0.8, C-1, C-5, and C-10 groups could improve GPx, CAT, and GSH levels, but no significant difference was found regarding SOD compared to the other groups. DPPH scavengers were tested by K-0.6, K-0.8 and C-1, C-5, C-10, C-0.8, C-0.4 and C-0.2 groups and compared to other groups improved. The fertility rate [70% (14/20)] was higher in C-1 than other groups. To conclude that k-CRG and C60HyFn supplementation can increase the quality parameters of cryopreserved buffalo semen after thawing and that 1 M C60HyFn can increase in vivo fertility of buffalo semen.

Effect of Different Concentrations of Melatonin on Ram Epididymal Spermatozoa Recovered Post-mortem under Oxidative Stress Conditions and Storage at 4 °C

The current study examines the protective effects of different melatonin concentrations on fresh ram epididymis spermatozoa after post-mortem recovery under normal and oxidative stress conditions and during liquid preservation (4^o C) at different times (24, 48, and 72h). The testes were obtained from a local slaughterhouse during the breeding season. Spermatozoa were isolated from cauda epididymidis. In experiment 1, the effects of adding different concentrations of melatonin (0, 15, 60, and 240 μg/mL) under normal and oxidative stress conditions were evaluated. Fifty μM of hydrogen peroxide was used to induce oxidative stress. Also, in experiment 2, the spermatozoa samples were chilled to 4^o C and stored for 72 h. Sperm total motility, viability, membrane, DNA integrity, and morphological abnormality were evaluated at 0, 24, 48, and 72 h after cooling storage. In experiment 1, melatonin treatment preserved viability increased TAC and SOD activities, and reduced MDA levels compared to control. Also, melatonin reduced the harmful effects of H2O2 under induced oxidative stress. In experiment 2, Melatonin at concentrations of 15 and 60 g/mL greatly increased sperm viability after 3 days of cold storage. Furthermore, it could have a significant protective effect on the motility of cooled sperm. Melatonin supplementation preserved higher sperm membrane integrity at concentrations of 15 and 60μg/mL, DNA integrity at a concentration of 15μg/mL, and abnormality at a concentration of 60μg/mL after 3 days of storage. The results suggest that melatonin can be used to reduce the adverse effects of induced oxidative stress in spermatozoa. Furthermore, ram epididymal spermatozoa could be stored at 4 °C for 72 h when treated with melatonin.

Factors Affecting the Survival of Ram Spermatozoa during Liquid Storage and Options for Improvement

Semen preservation is an essential component of reproductive technologies, as it promotes genetic gain and long-distance semen transport and multiplies the number of ewes able to be inseminated per single ejaculate. However, the reduced temperature during cold storage at 5 or 15 °C inflicts sub-lethal damage to spermatozoa, compromising sperm quality and the success of artificial breeding. New and emerging research in various species has reported the advantages of storing spermatozoa at higher temperatures, such as 23 °C; however, this topic has not been thoroughly investigated for ram spermatozoa. Despite the success of storing spermatozoa at 23 °C, sperm quality can be compromised by the damaging effects of lipid peroxidation, more commonly when metabolism is left unaltered during 23 °C storage. Additionally, given the biosafety concern surrounding the international transport of egg-yolk-containing extenders, further investigation is critical to assess the preservation ability of synthetic extenders and whether pro-survival factors could be supplemented to maximise sperm survival during storage at 23 °C.

The effects of glutathione supplementation on post-thawed Turkey semen quality and oxidative stress parameters and fertilization, and hatching potential

This study was conducted to investigate the effect of semen extenders enriched with glutathione (GSH) on in vitro quality parameters and fertility of post-thawed turkey. In experiment 1, pools of semen diluted in glucose-based extender containing 0.5, 1, and 2 mM of GSH were cryopreserved. During the next step, a different variable such as motility and motion parameters, plasma membrane integrity (PMI) and functionality (PMF), DNA integrity, lipid peroxidation (MDA), total antioxidant capacity (TAC), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity were determined in the post-thawed samples. In the second experiment, artificial insemination was used to evaluate the fertility and hatchability performances of the post-thawed semen. The results of the first experiment showed that the extenders supplemented with 2, 1 and 0.5 mM of GSH had higher levels (p ≤ 0.05) of motility and motion parameters, PMI, PMF, TAC, CAT and SOD activity and lower abnormal morphology, DNA damage, and lipid peroxidation respectively in comparison to the control group (only extender with semen). Notably, the second experiment showed a higher rate of fertility (p ≤ 0.05) in 2 mM of GSH compared to the control group. It can be concluded that adding 2, 1 and 0.5 mM of glutathione leads to an improvement in the survival of the post-thawed turkey, while 2 mM of GSH can increase the fertility strength of the turkey sperm; hence it can be used to improve fertility and hatchability performance.

Melatonin and canthaxanthin enhances sperm viability and protect ram spermatozoa from oxidative stress during liquid storage at 4°C

Antioxidants are used to minimize oxidative stress during liquid semen storage. The main aim of current study was to elucidate effect of supplementing melatonin and canthaxanthin in Tris-based extender could enhance seminal quality of ram at 4°C up to 72 h. A total of 48 ejaculates were collected from breeding Magra rams (n = 8) and were preliminarily subjected for various macroscopic and microscopic semen evaluation tests. These ejaculates were pooled and divided into three equal aliquots. Two aliquots were diluted (1:10) using extender encompassing final concentration of 1mM melatonin and 25 µM canthaxanthin and stored at 4°C. Third aliquot with extender only was kept as control. Structural and functional seminal changes were observed at different time points of preservation. Results revealed that mean values for progressive sperm motility, viability and total antioxidant capacity were significantly higher (p < 0.05) in melatonin group while hypo-osmotic swelling test was significantly (p < 0.05) higher in canthaxanthin group. Total sperm abnormalities and malondialdehyde levels were significantly (p < 0.05) lower in both treatment groups indicating their antioxidant efficacy in protection of spermatozoa from oxidative stress. Results of study indicated that supplementation of these antioxidants to ram semen could be used to enhance storage life of liquid semen at 4°C up to 72 h.

Cooled storage of semen from livestock animals (Part II): Camelids, goats, and sheep

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques in cooled storage of semen from livestock animals such as camelids, goats, and sheep. Facing worldwide environmental changes and a trend towards more conscious and healthy eating behaviors, the development of a stable animal breeding industry is a significant challenge for the near future. In the present review, factors influencing semen handling in camelids, goats and sheep are described and relevant methods as well as current trends to improve liquid-storage of cooled semen are discussed, including extenders, additives, cooling rates, and storage temperatures. The species-specific physiology and resulting challenges are taken into consideration. While the main problem for camelid semen processing is the relatively greater viscosity as compared with that of some other animals, the deciding factor for successful artificial insemination (AI) in goats and sheep is the site (i.e., cervical or vaginal) of semen placement in the reproductive tract. Due to the type of cervical anatomy, the penetration of the cervix when using AI instruments is rather difficult. Furthermore, the seminal plasma of small ruminants affects the interaction with milk-based extenders and egg yolk which results in species-specific regimens for cooled liquid-preservation. Comparing all three species, the greatest pregnancy rates were obtained by AI with goat semen after cooled liquid-storage for several days.

Use of melatonin in sperm cryopreservation of farm animals: A brief review

Melatonin (MT) is a potent antioxidant with useful applications in several fields. Due to the capacity to scavenge free radicals and enhance cellular endogenous antioxidant defenses, MT is widely used in sperm cryopreservation to protect against oxidative stress-induced damage in frozen-thawed sperm. In this article, there is a review of positive effects of MT supplementation in cryopreservation of sperm from domestic ruminants and swine. There is direct or indirect scavenging of free radicals, preventing lipid peroxidation (LPO), and reducing oxidative stress, therefore, protecting membrane and DNA integrity, enhancing post-thaw antioxidant and enzymatic functions to maintain mitochondrial functions and activity, and regulating ATP production and utilization leading to maintenance of sperm quality, motility, and viability. In addition, MT reportedly inhibits sperm apoptosis, potentially by enhancing sperm viability and modulating abundances of mRNA transcripts.

Role of Antioxidants in Cooled Liquid Storage of Mammal Spermatozoa

Cooled preservation of semen is usually associated with artificial insemination and genetic improvement programs in livestock species. Several studies have reported an increase in reactive oxidative species and a decrease in antioxidant substances and sperm quality parameters during long-term semen storage at refrigerated temperatures. The supplementation of antioxidants in extenders before refrigeration could reduce this detrimental effect. Various antioxidants have been tested, both enzymatic, such as superoxide dismutase and catalase, and non-enzymatic, such as reduced glutathione, vitamins E and C and melatonin. However, the problem of oxidative stress in semen storage has not been fully resolved. The effects of antioxidants for semen-cooled storage have not been reviewed in depth. Therefore, the objective of the present study was to review the efficiency of the supplementation of antioxidants in the extender during cooled storage of semen in livestock species.

Melatonin can improve viability and functional integrity of cooled and frozen/thawed rabbit spermatozoa

Melatonin is known to protect sperm against freezing-inflicted damage in different domestic species. The aim of the study was to evaluate the effect of supplementation of semen extender with melatonin on the quality and DNA integrity of cooled and frozen/thawed rabbit spermatozoa. We also investigated whether the addition of melatonin to the semen extender could improve the fertility of rabbit does artificially inseminated with frozen/thawed semen. Semen samples collected from eight rabbit bucks were pooled and then diluted in INRA-82 supplemented either with (0.5, 1.0 or 1.5 mM) or without (0.0 mM) melatonin. Diluted semen was cooled at 5°C for 24 hr. For cryopreservation and based on the first experiment's best result, semen samples were diluted in INRA-82 in the presence or absence of 1.0 mM melatonin and then frozen in 0.25 ml straws. Following cooling or thawing, sperm quality and DNA integrity were evaluated. Furthermore, the fertility of frozen/thawed semen was investigated after artificial insemination. Supplementation of semen extender with 1.0 mM melatonin improved (p < .05) motility, viability, membrane and acrosome integrities in cooled semen compared with other groups. Sperm quality and DNA integrity were higher (p < .05) in frozen/thawed semen diluted in 1.0 mM melatonin-supplemented extender than in the control group. Conception and birth rates were higher in does inseminated with 1.0 mM melatonin treated semen compared with the controls. In conclusion, supplementation of semen extender with 1.0 mM melatonin improved the quality of cooled and frozen/thawed rabbit spermatozoa. Melatonin can preserve DNA integrity and enhance the fertility of frozen/thawed rabbit spermatozoa.