Effects of L-Carnitine on Equine Semen Quality During Liquid Storage

l-carnitine enhances the kinematics and protects the sperm membranes of chilled and frozen-thawed Peruvian Paso horse spermatozoa

l-carnitine (LC) transports fatty acids to the mitochondria for energy production, reducing lipid availability for peroxidation through β-oxidation. This research examines the effect of LC supplementation to two skimmed milk-based extenders on the cryosurvival of chilled (5°C) and frozen-thawed Peruvian Paso horse spermatozoa .An initial experiment determined the optimal LC concentration (0, 1, 5, 10, 25, and 50 mM) when added to INRA-96® and UHT (skimmed milk + 6% egg yolk) extenders, using nine ejaculates from three stallions chilled for up to 96 h. Subsequently, the effect of 25 mM LC supplementation (the optimal concentration) on chilling (INRA-96) and freezing (INRA-Freeze®) extenders was evaluated using eight pooled samples from sixteen ejaculates (2 ejaculates/pool) from four stallions. Results indicated that all LC concentrations produced significantly higher values (P<0.05) for kinematic variables (total [TM] and progressive motilities, curvilinear [VCL] and straight-line [VSL] velocity, and beat-cross frequency [BCF]), and the integrity of plasma/acrosome membranes (IPIA) compared to non-supplemented chilled sperm samples for up to 96 h with both extenders. Moreover, the use of 25 mM LC was more efficient (P<0.05) in preserving the post-chilled values of velocity, BCF, and IPIA for the long term than lower LC concentrations (1-10 mM). Post-thaw values of total motility, the amplitude of lateral head displacement (ALH), and IPIA were significantly improved (P<0.05) when INRA-Freeze extender was supplemented with 25 mM LC. In conclusion, supplementation of l-carnitine to skimmed milk-based extenders enhanced kinematic variables and protected the membrane integrity in chilled and frozen-thawed Peruvian Paso horse spermatozoa.

Effect of nutraceutical supplementation on semen quality in stallions

BACKGROUND

The use of reproductive biotechnologies in equine practice has shown that some stallions are subfertile, so ways to improve fertility have been sought.

OBJECTIVE

This study aimed to evaluate the effect of nutraceutical supplementation on improving semen quality in Quarter Horse stallions.

METHODS

Semen from six Quarter Horse stallions was assessed for 4 months every 20 days using the computer-assisted semen analysis system. They were evaluated for 60 days before supplementation; then, the same stallions were re-evaluated for 60 days with nutraceutical supplementation (30 g/day).

RESULTS

Volume showed no significant difference (p > 0.05) with nutraceuticals. Sperm concentration (10x6 ) was significantly higher with supplementation (339.4 ± 17.5 sperm/mL) than without supplementation (224.6 ± 19.9). Sperm abnormalities (%) were significantly (p < 0.05) lower with supplementation (14.3 ± 0.6) than without supplementation (19.1 ± 0.4). Sperm kinematic parameters, total motility (TM), progressive motility (PM), rectilinear velocity (VSL), the velocity of the trajectory (VAP) and curvilinear velocity (VCL), were significantly better with supplementation (p < 0.05).

CONCLUSIONS

Based on the results, it is concluded that nutraceutical supplementation improved semen parameters in Quarter Horse stallions.

Combined addition of L-carnitine and L-proline improves cryopreservation of dairy goat semen

Cryopreservation of semen renders artificial insemination easier and cheaper compared to use of fresh semen. However, the cellular oxidative stress, toxicity of cryoprotectants, and osmotic imbalance may lead to a decline in semen quality and fertilization ability during the process of cryopreservation. L-carnitine and L-proline have been demonstrated to possess effective antioxidant properties in cryopreservation, with the latter also exhibiting excellent permeability and thus being utilized as a permeable cryoprotectant in the field. The aim of this study was to investigate the effects of LC and LP on cryopreservation of semen of dairy goats. After thawing, sperm motility, membrane integrity, and acrosome integrity rate of cryopreserved semen treated with LC (50 mM) were significantly higher compared to the untreated control samples. Based on this premise, we conducted experiments to assess the cryoprotective efficacy of different concentrations of LP. The findings demonstrated that the inclusion of 50 mM LP resulted in improved sperm motility compared to other concentrations. Furthermore, the levels of damaging reactive oxygen species and the malonyldialdehyde marker for oxidative stress were significantly lower in goat semen treated with these concentrations of LC and LP compared to semen exposed to other treatments. Semen treated with LC and LP also exhibited good fertilization ability during both in vitro fertilization and artificial insemination. Thus, LC (50 mM) and LP (50 mM) improve cryoprotection of dairy goat sperm which suggests that addition of these compounds will be highly beneficial to the development of dairy goat breeding.

The interference of ozone gas in kinects and mitochondrial potential of equine sperm submitted on cryopreservation

The objective of this study was to evaluate the effects of the addition of different concentrations of ozone to quarter horse semen submitted to cryopreservation. Six ejaculates from four stallions were collected and were divided in four experimental groups: a control group (BotuCRIO® extender) and three other groups with BotuCRIO® ozonized at concentrations of 6, 8 and 12 μg of O₃/mL. The semen samples were diluted (200 x 10⁶ spermatozoa/mL), filled in straws and frozen. After thawing (37 ºC, 30s), the samples were evaluated at 0, 30 and 60 minutes of incubation regarding sperm kinetics by a computer-assisted sperm analysis (CASA), and plasma membrane integrity (PMI), acrosome integrity (ACi) and mitochondrial membrane potential (MMP) by fluorescent probes. There was a reduction in the kinetic parameters total motility (TM), progressive motility (PM), curvilinear velocity (VCL), straight line velocity (VSL) and average path velocity (VAP) in all groups during the thermoresistance test (TT), a pattern also found in PMI and MMP analyses (p<0.05). There was no difference (p>0.05) between the control and treatment (6, 8, and 12 μg of O₃/mL) groups, in any of the evaluated times for the kinetic parameters TM, linearity (LIN), straightness (STR), wobble index (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF). Regarding the VCL, VSL and VAP parameters, the group treated with 6 μg did not differ from the control or from 8 μg, but was higher than 12 μg at 30 and 60 minutes. ACi and PMI did not differ between groups (p>0.05), but PMI was lower in groups 8 μg and 12 μg compared to the control and 6 μg (p<0.05). It was concluded that the addition of ozone does not present beneficial effects for cryopreservation of equine semen at the concentrations used and decreases important parameters of fertility.

Diluent Containing Dimethylformamide Added With Sucrose Improves In Vitro Quality After Freezing/Thawing Stallion Sperm

The aim of this study was to investigate the effects of sucrose on post-thawed equine semen quality. Semen samples (n = 24) were collected from six stallions. They were diluted (200 × 10⁶ sperm/mL) in a freezing medium based on skimmed milk, egg yolk, dimethylformamide, and supplemented with sucrose at concentrations of 0 (Control), 25, 50, and 100 mM and in a commercial extender (BotuCrio). Subsequently, they were filled in straws (0.5 mL) and subjected to freezing and storage (-196°C). Immediately after thawing (37°C, 30 seconds), semen samples were evaluated for kinetics (CASA), plasma and acrosomal membrane integrity, and mitochondrial membrane potential (flow cytometry). The addition of 50 and 100mM sucrose to the freezing extender increased (P < .05) the parameters of TM, PM, VCL, VSL, and VAP, compared to the control group. The WOB parameter of the group supplemented with 100 mM sucrose was higher (P < .05) than the control group. Higher values ​​(P < .05) of ALH and BCF were observed in groups treated with sucrose (25, 50, and 100 mM), compared to BotuCrio. The semen frozen in the presence of 100 mM sucrose presented higher percentages (P < .05) of sperm with intact plasma and acrosomal membranes, and high mitochondrial membrane potential in relation to the other groups. It is concluded that the addition of sucrose to equine semen freezing extender increase motility (50 and 100 mM), plasma and acrosomal membrane integrity preserve, and high sperm mitochondrial membrane potential (100 mM) after thawing.

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.

Relationships between Seminal Plasma Metabolites, Semen Characteristics and Sperm Kinetics in Donkey (Equus asinus)

Simple Summary

A deeper knowledge of reproductive biology may be helpful in the donkey to avoid the risk of extinction that some breeds are facing. The evaluation of metabolites in seminal plasma provides crucial information for the knowledge of donkey sperm metabolism, for obtaining comparative information with other species, as well as for providing useful elements for the formulation of extenders for sperm dilution and conservation. Moreover, correlations of seminal metabolites with sperm kinetics highlight new possible markers of sperm quality. Using multivariate analysis, all metabolic, seminal, and spermatic data were merged in a single dot that grouped individual stallions within clusters in the Cartesian axes according to the different spermatic characteristics. This amount of information also allows to shed light on the effects of total or partial removal of seminal plasma for improving sperm preservation. The inclusion in the study of an azoospermic individual represents a further discriminating element in the analysis of sperm quality under physiological and pathological conditions.

Abstract

This study aimed to evaluate donkey seminal plasma metabolites and relate this information to the main characteristics of sperm quality. Sperm kinetics from 10 donkey stallions were analyzed with a computerized system at the time of collection (T0) and after 24 h storage at 4 °C (T24). Seminal plasma was frozen at −80 °C for subsequent proton nuclear magnetic resonance (¹H NMR) spectroscopy. On three stallions, semen collection was repeated monthly for three times and sperm analysis also included mitochondrial activity and oxidative status. One stallion was azoospermic and a second semen collection was performed after one month. In the seminal plasma, 17 metabolites were identified; their levels showed numerous significant variations between the azoospermic and the normospermic individuals and grouped in well-defined clusters in a multivariate analysis. Comparing individuals with high and low sperm motility, the only discriminating metabolite was phenylalanine, whose levels were lower in the latter, as in the azoospermic individual. Phenylalanine was also the only metabolite highly correlated with all sperm kinematic parameters at T24. In conclusion, the present study has provided relevant information on the chemical characteristics of donkey semen, identified relationships between seminal metabolites, semen parameters, and sperm kinetics, and offered insights for future technological applications.

Protective effect of L-carnitine on apoptosis, DNA fragmentation, membrane integrity and Lipid peroxidation of spermatozoa in the asthenoteratospermic men

This in vitro study aimed to measure the ameliorative effect of L-carnitine against apoptosis, DNA fragmentation, membrane integrity and lipid peroxidation of spermatozoa from men with asthenoteratozoospermia (ATS). L-carnitine has an impressive effect on boosting the quality and quantity of spermatozoa and also can prevent apoptosis induction. For this purpose, semen samples were collected from 50 ATS men. Semen was divided into control and L-carnitine (0.5 mg/ml) groups at 2, 4, 6 and 24 hr. Concentrating on the reasons for apoptosis is an arduous process, but in the present research for this evaluation, mitochondrial membrane potential (MMP), DNA fragmentation by TUNEL and SCD methods, and lipid peroxidation were carried out. Also, sperm viability was performed. In the control group, MDA levels were increased significantly at 6 hr; however, sperm viability was decreased significantly at 4 and 6 hr. Moreover, in the L-carnitine group, TUNEL, SCD and MDA levels were decreased significantly and MMP and viability were increased significantly compared with the control group. In this writers' view, in vitro L-carnitine treatment can downregulate apoptosis in men with ATS.