Effects of the Tris, Tes, or skim milk based extender on in vitro parameters of ram spermatozoa during liquid storage

Effects of different extenders, storage temperatures, and antioxidant supplementation on chilled semen quality: a review

The successful preservation of ram semen is essential to promote genetic variability, ensure semen transportation, and inseminate multiple ewes. Currently, either animal or plant-based lipoprotein-based extenders are used for semen preservation. Animal product-based extenders include milk and egg yolk, while soybean lecithin is a plant-based extender. Although extenders containing products of animal origin better preserve the quality of chilled semen, the in vivo efficacy after 24 h of storage is still of great concern. Storage temperature is another important and effective factor in preserving sperm quality, whereby different storage temperatures are adopted to enhance the storage life of sperm. Low temperatures (4-5 °C) better preserve sperm quality for a longer duration than high temperatures (15, 20, and 25 °C). Moreover, antioxidant supplementation has a positive impact on sperm quality during liquid storage. The current review summarizes the outcomes of various extenders, different storage temperatures, and antioxidant supplementation on the liquid storage of ram sperm.

Effect of C-phycocyanin purified from Spirulina platensis on cooled ram semen quality and in vivo fertility

This research sought to purify C-phycocyanin (C-PC) from Spirulina platensis and investigate its potential in enhancing the quality parameters and in vivo fertility of ram semen subjected to cooled storage at 5 °C, when using a skim milk (SM) based semen extender. The purification process of C-PC involved cold maceration, pre-purification using chitosan and activated charcoal, followed by purification through aqueous two-phase extraction (ATPE) and ion-exchange chromatography. Afterward, fifty ejaculates were collected from 4 fertile Boujaâd rams and extended using the SM extender at 37 °C, enriched with 0 μg/mL (control), 1.2 μg/mL, 2.4 μg/mL, 3.6 μg/mL, or 4.8 μg/mL of C-PC. The diluted semen was subsequently cooled to 5 °C using a controlled cooling process, with a gradual cooling rate of approximately 0.5 °C per minute, and its quality parameters were evaluated after 0, 4, 8, and 24 h of cooling storage. Then, its fertilization ability after 4 h of cooling storage was evaluated using artificial insemination. The adopted purification process yielded a grade analytical purity of 4.06. Additionally, semen extended in SM with a 2.4 μg/mL C-PC supplement displayed significant (P < 0.0001) enhancement in total motility, progressive motility, curvilinear velocity, straight-line velocity, average path velocity, viability and lipid peroxidation of ram semen at 0, 4, 8, and 24 h of cooling storage. These improvements were observed in direct comparison to both the control group and the other C-PC concentrations. Regarding fertility rates, semen extended in SM with a 2.4 μg/mL C-PC recorded a 76 % rate, a notable increment from the 63 % observed in ewes inseminated by semen extended in SM alone, although the difference was not statistically significant (p > 0.05). These findings underscore the promising potential of C-PC as a natural supplement for enhancing semen quality, warranting further investigations.

Effects of extender type and storage time on sperm quality parameters of Kail ram semen stored at 5 °C

The study was designed to evaluate the effect of different extenders and storage times on sperm quality parameters of extended Kail ram semen. Semen was collected from five adult Kail rams using an artificial vagina. Semen samples with >70% total sperm motility were pooled, diluted with Tris (TR), sodium citrate (SC), and skim milk (SM)-based extenders, and stored at 5 °C. Sperm motility and kinematics, viability, and plasma and acrosomal membrane integrity were assessed every 24 hrs for 120 hrs. Sperm longevity was estimated by placing semen in a water bath at 37°C to assess sperm kinematics. Storage time as the main effect had a negative (P < 0.05) impact on sperm quality parameters. The percentages of total motile (TM), progressive motile (PM), rapid, and medium progressive (MP) motile sperm were similar at 24 hrs of storage for the three extenders. However, semen extended in TR had a higher (P < 0.05) percentage of TM, PM, rapid, and MP sperm compared to SM and SC extenders at 48 hrs of storage. The sperm kinematics (VCL, VSL, VAP, and ALH) of progressive sperm were similar for all three extenders up to 72 hrs of storage. In addition, semen extended in TR had a higher (P < 0.05) percentage of sperm with intact plasma and acrosomal membranes at a storage time of 48 hrs. At 37 °C, the percentage of TM and PM sperm was higher (P < 0.05) in the TR extender than in the SM and SC extenders at 60 minutes and beyond. In conclusion, the Kail ram sperm extended in TR and stored at 5 °C maintained better quality after 48 hrs storage than sperm extended in SM and SC extenders. At 37 °C, sperm extended in TR also retained better quality parameters at 60 min and afterward than sperm extended in SM and SC.

An optimized centrifugation protocol for ram sperm ensuring high sample yield, quality and fertility

The optimization and implementation of artificial insemination (AI) in sheep is necessary to increase the livestock productivity through enhanced control of reproductive function. Sperm centrifugation is a common procedure in the ejaculate handling in AI and other assisted reproductive technologies (ART), as part of new methods of sperm analysis, selection or preservation. However, our research group previously established that this simple procedure might cause a large sperm loss and induce deleterious effects on the sperm function of the ovine species when high centrifugation forces are employed. To our knowledge, there are no studies on combined effect of extender and different centrifugal forces on ram sperm yield and quality. Furthermore, evidence of in vivo fertility rate using sperm obtained with various centrifugation forces is also lacking in this species. Thus, the objective of this work was to define the ideal conditions for ram semen centrifugation that will achieve the best quantity and quality sample to ensure unaffected fertilization ability of centrifuged ram sperm. The Experiment 1 evaluated the effect of the centrifugation procedure of two extenders (INRA 96 and Tyrode's) and two cooling protocols (Rapid and Slow Refrigeration -35 °C to 15 °C-) on sperm recovery rate and quality (motility and kinetic parameters, viability, apoptosis and mitochondrial activity). INRA 96 combined with Slow Refrigeration and Tyrode's at room temperature registered the highest sperm recovery and quality values (P ≤ 0.05). In Experiment 2, the influence of three centrifugal forces (600, 1200 and 6000×g for 10 min) was assessed immediately after centrifugation on the technical performance and sperm functionality in diluted samples with INRA 96 and Tyrode's at the conditions set out in Experiment 1. The lowest pellet weight (P ≤ 0.05) without harmful effect on sperm physiological status (P > 0.05) was achieved at 1200×g, since 6000×g induced sperm motility damage (P ≤ 0.05) with both extenders. Finally, to ensure the total safety of the centrifugation protocol, Experiment 3 tested in a combined in vitro and in vivo test the effect of these three centrifugal forces on ram sperm quality after dilution (INRA 96) and liquid storage (6-8 h at 15 °C). The damage produced by 6000×g on sperm motility (P ≤ 0.05) was maintained over time, coinciding with a lower fertility (P ≤ 0.05). In conclusion, ram sperm can be centrifuged in INRA 96 extender up to 1200×g for 10 min at 15 °C as secure values with high recovery rates and without detrimental effects on sperm quality and fertility.

Ultrastructural Modification of Ram Sperm Frozen with Cyclohexanediol and Trehalose

In this study, the effects of trehalose and 1, 3-cyclohexanediol (1, 3-CHD) on the ultrastructure of frozen-thawed ram sperm were assessed and compared. In the control group, sperm were frozen without trehalose and 1, 3-CHD. In the trehalose group, 100 mM trehalose was used for sperm cryopreservation. In the cyclohexanediol group, the freezing extender contained 100 mM 1, 3-CHD. The transmission electron microscope (TEM) was used to observe the ultrastructural alterations of sperm. For verification of the TEM results, the plasma membrane and acrosome integrity of ram frozen sperm was assessed. Three fertility-proven rams were used in this study. Semen collection was repeated 6 times. The collected semen was pooled to preclude the individual difference each time. The sperm collected from a representative ram were used for ultrastructural observation. The TEM results indicated extensive and severe cryoinjuries on the main organelles of ram frozen sperm. Some alterations in plasma membrane, including detachment, rupture, dilation, or loss, appeared in post-thaw sperm. The bending shape and leakage of genetic materials were also observed in the nucleus. In addition, the outer acrosome membrane in some frozen sperm was broken or partly lost. Further, leakage of the inner contents of acrosomes also occurred. Sperm mitochondria was negatively influenced by cryopreservation. With 1, 3-CHD or trehalose, the percentage of sperm with normal acrosomes was 62% or 64%, and it was significantly higher than that of the control (41.51%, p < 0.05). However, different from trehalose, 1, 3-CHD cannot efficiently protect the post-thaw integrity of the plasma membrane (48.09% vs. 26.92%, p < 0.05). The TEM results were consistent with the quality assessment of frozen-thawed sperm. Collectively, trehalose and 1, 3-CHD can mitigate cryoinjuries on sperm ultrastructure. The cryoprotective effects of trehalose on sperm plasma membrane are superior to 1, 3-CHD. Sperm plasma membrane is the most sensitive to cryoinjuries, followed by acrosomes, mitochondria, and nuclei.

Effect of Sperm Concentration and Storage Temperature on Goat Spermatozoa during Liquid Storage

The use of cooled semen is relatively common in goats. There are a number of advantages of cooled semen doses, including easier handling of artificial insemination (AI) doses, transport, more AI doses per ejaculate, and higher fertility rates in comparison with frozen AI doses. However, cooled semen has a short shelf life. The objective of this study was to examine the effect of temperature and sperm concentration on the in vitro sperm quality during liquid storage for 48 h, including sperm motility and kinetics, response to oxidation, mitochondrial membrane potential (MMP) and DNA fragmentation in goats. Three experiments were performed. In the first, the effects of liquid preservation of semen at different temperatures (5 °C or 17 °C), durations (0, 24 and 48 h) and sperm concentrations (250 × 10⁶ sperm/mL (1:2 dilution rate), 166.7 × 10⁶ sperm/mL (1:3 dilution rate) or 50 × 10⁶ sperm/mL (1:10 dilution rate)) on sperm motility and kinetics were studied. In the second experiment, the effect of temperature, sperm washing and concentration on sperm motility and DNA fragmentation was studied. Finally, the effect of sperm concentration and duration of storage at 5 °C on sperm motility, response to oxidative stress and MMP was examined. We found that refrigerated liquid storage of goat sperm impaired sperm quality, such as motility, MMP and response to oxidation, as storage time increased; however, sperm DNA fragmentation index was not significantly affected. Liquid storage at 5 °C preserved higher total motility than at 17 °C. Moreover, we observed that the reduction of sperm concentration below 500 × 10⁶ sperm/mL did not seem to improve the quality of spermatozoa conserved in milk-based extender in the conditions tested.

Mechanisms of ROS-induced mitochondria-dependent apoptosis underlying liquid storage of goat spermatozoa

Liquid storage of spermatozoa is important for artificial insemination and herd genetic breeding. However, the extended time of storage inducing the rapid decline in spermatozoa quality limits the development of this technology. The molecular mechanisms underlying liquid storage of spermatozoa remain largely unexplored. In this study, the effects of liquid storage on functional quality of spermatozoa were assessed in goat (Capra hircus). The time-dependent decline in spermatozoa motility showed a strong correlation with the significant increase in apoptosis. Moreover, apoptosis-related ultrastructural changes were observed, especially the defects in mitochondria. A significant decrease in mitochondrial membrane potential and changes in the expression of mitochondrial apoptosis-related proteins indicated mitochondrial dysfunction and mitochondrial apoptotic pathway activation. Notably, the abnormally high level of reactive oxygen species (ROS) caused by liquid storage resulted in oxidative damage to mitochondria and accelerated mitochondria-dependent apoptosis, as demonstrated by the addition of ROS scavenger N-acetylcysteine. Furthermore, critical differentially expressed proteins involved in mitochondria-dependent apoptosis and antioxidant defense were identified and profiled by quantitative proteomic analysis, facilitating the understanding of molecular regulation of ROS-induced mitochondria-dependent apoptosis. These outcomes provide insights into the mechanisms underlying liquid storage of goat spermatozoa and enhance the progress of semen storage technology.

Effect of three commercial extenders on sperm motility and fertility in liquid ram semen stored at 15 °C or 5 °C

The effect of different extenders on sperm motility and fertility was evaluated during liquid storage of ram semen at 5 °C and 15 °C. The semen was collected, pooled and diluted in three commercial extenders: Inra 96® (INRA) based on skimmed milk, Biladyl® A fraction (BIL) based on egg yolk, and Ovixcell® (OVIX) based on soybean lecithin. Then, sperm motility was evaluated at 0, 6, 24, 48, 72 and 96 h. In order to evaluate fertility, samples stored at 15 °C were used after dilution in INRA and OVIX. Results showed that progressive motility was significantly higher up to 72 h of storage in sperm samples maintained at 5 °C in comparison with 15 °C, similarly for each tested diluent. When samples were stored at 5 °C in OVIX, kinematic parameters such as velocity (except curvilinear velocity, VCL), trajectory [linearity (LIN), straightness (STR), wobble (WOB)], amplitude of lateral head displacement (ALH) and beat/cross frequency (BCF) were higher than in INRA and BIL. No significant differences in pregnancy rate were detected between INRA (62.6%) and OVIX (58.9%). In conclusion, liquid storage at 5 °C with OVIX extender is an interesting option since non-animal components are used, and this extender offers similar in vitro and in vivo efficacy as other extenders containing animal components.

Liquid storage of dromedary camel semen in different extenders

This study was conducted to assess the effects of commercial extenders and storage temperature on dromedary camel sperm quality during liquid preservation. In Experiment 1, ejaculates (n = five males; replicated seven times) were split and diluted with synthetic (OPTIXcell, EquiPlus, INRA96, Bioxcell or AndroMed; Experiment 1a) or egg-yolk based (Biladyl, Green buffer or Triladyl; Experiment 1b) extenders and stored for 48 h at 4 °C. In Experiment 2, split ejaculates (n = five males; replicated six times) were used to directly compare Green buffer, OPTIXcell and Triladyl extenders over 48 h of storage at 4 °C. Ejaculates collected in Experiment 3 (n = five males; replicated five times) were diluted with Green buffer or Triladyl before chilled storage for 48 h at 4 or 15 °C. Sperm kinematics, viability and acrosome integrity were assessed during liquid storage. In Experiment 1a, there was the greatest total sperm motility (TM) in the OPTIXcell group following 24 and 48 h of storage, while in Experiment 1b, there was the greatest TM after 48 h of storage with Triladyl and Green buffer. In Experiment 2, there were greater TM and viable acrosome intact spermatozoa in the Triladyl and Green buffer than with OPTIXcell group. In Experiment 3, there was a greater TM in the Triladyl than Green buffer group at 24 and 48 h of storage regardless of storage temperature (which had no effect on sperm quality). In conclusion, camel sperm have greater viability when preserved in liquid form for 48 h following dilution with Triladyl and storage at either 4 or 15 °C.

Influence of sperm filtration and the addition of glycerol to UHT skimmed milk- and TEST-based extenders on the quality and fertilizing capacity of chilled ram sperm

The poor fertility of ram semen stored chilled for long periods has encouraged the development of protocols designed to improve the kinetic vigour and cervical barrier-crossing capacity of sperm. The present work evaluated the effect of sperm selection with Sephadex filtration and the supplementation of 2% glycerol (GLY) to extenders based on ultra-heat-treated skimmed milk (UHT) or Tris-Tes-Glucose (TEST) on ram sperm kinetic parameters, plasma membrane integrity, acrosome integrity, mitochondrial function and fertilizing ability, over long chilling times. The results showed that for non-filtered semen, values for progressive sperm motility (%PSM), straight line velocity (VSL, μm/s) and the percentage of sperm with an intact plasma membrane/intact acrosome/a high mitochondrial function index (%IPIAHM) at all times up to 96 h of chilling were higher when the UHT extender (P < 0.01) was used compared to TEST extender irrespective of the presence of GLY. When semen was previously filtered with Sephadex, the addition of GLY to the UHT extender improved total motility (%TM), the %PSM and the VSL at 96 h compared to all other treatments (P < 0.01). The best results of all were obtained with non-filtered semen and UHT either with or without GLY. Heterologous IVF using zona-intact bovine oocytes was used to assess the fertilizing capacity of non-filtered fresh (FS0), chilled-for-24 h (CS24) or chilled-for-48 h (CS48) ram semen diluted in UHT extender (GLY-free). Heterologous IVF showed that ram sperm, either FS0, CS24 or CS48, were equally capable of penetrating zona pellucida intact bovine oocytes, leading to pronuclear formation and hybrid embryo cleavage (46.3 ± 3.2; 48.8 ± 3.2; and 43.3 ± 3.5, respectively). No differences were seen with respect to fresh sperm in terms of sperm binding, penetration, polyspermy, pronucleus formation or cleavage rates (P > 0.05). In conclusion, neither Sephadex filtration nor addition of glycerol provided extra benefits to ram sperm chilled up to 96 h. Chilled, non-filtered sperm extended with UHT without GLY showed better sperm functionality than did similar sperm extended with TEST extenders. Indeed, sperm diluted in UHT extender, maintained fertilizing ability up to 48 h.