The cryoprotective effects of ascorbic acid supplementation on bovine semen quality

Effect of ascorbic acid on metabolic status, lipid peroxidation, antioxidant activity and quality of frozen Indian red jungle fowl (Gallus gallus murghi) semen

The Indian red jungle fowl population is decreasing in its natural habitat. Its conservation through semen cryopreservation with sufficient live sperm recovery rate is requisite where ascorbic acid could play significant role to mitigate cryo-incited injuries. The objective was to elucidate the effect of ascorbic acid on freezability of Indian red jungle fowl sperm. Pooled semen was aliquoted and diluted (1:5) with red fowl extender having ascorbic acid: 0.0 (control), 1.0, 2.0 and 4.0 mM. Diluted samples were cryopreserved and semen quality was assessed at post-dilution, cooling, equilibration and freeze-thawing stages. Sperm metabolic status, antioxidant potential and lipid peroxidation were studied at post-dilution and freeze-thawing. Sperm motility did not differ (p > .05) in experimental extenders and control at post-dilution and cooling; however, it was recorded higher (p < .05) with ascorbic acid at 2.0 mM compared with other levels at post-equilibration and post-thawing stage. Sperm viability, plasma membrane and acrosome intactness were recorded higher (p < .05) with 2.0 mM ascorbic acid compared with other concentrations of ascorbic acid at all stages of cryopreservation. Sperm metabolic status and antioxidant potential were recorded higher (p < .05), while lipid peroxidation was recorded lowest (p < .05) with 2.0 mM ascorbic acid compared with 1.0, 4.0 mM and control. In conclusion, ascorbic acid at 2.0 mM in red fowl extender improves quality, metabolic status and antioxidant potential of frozen Indian red jungle fowl semen through ameliorating lipid peroxidation.

Effects of Extenders Supplementation with Gum Arabic and Antioxidants on Ram Spermatozoa Quality after Cryopreservation

Semen cryopreservation is very important in animal agriculture to maximize the number of daughters of genetically superior males and to distribute the cryopreserved semen of good males all over the world. However, the freezing process generates some damage to sperm that reduce their fertilizing ability after thawing. Moreover, egg yolk, which is the most common animal-origin cryoprotectant used in semen dilution, is considered a source of biosecurity risk. In the current study, we aimed to compare the replacement of egg yolk in the extender by gum arabic (5%) along with supplementation with antioxidant cysteine or ascorbic acid on semen quality and freezability in Noemi rams in vitro. Semen from six rams were collected with an artificial vagina two times per week. Semen evaluation parameters such as color, volume, pH, general motility, percentage motility, concentration and cell viability ratio were assessed. Spermatozoa motility and concentration were estimated with the computer-assisted semen analysis system. The semen samples were frozen using a Tris extender containing either 15% egg yolk or 5% gum arabic. For antioxidant-supplemented extenders, cysteine or ascorbic acid was dissolved at concentrations of 0.10, 0.50 or 1.0 mM in egg yolk or gum arabic extender. The semen from each ejaculate of each ram were resuspended with a specific extender with glycerol (5%); the final volume after dilution was 1 mL semen to 4 mL extender. The samples were then cooled to 4 °C for 120 min, loaded into 0.5 mL straws and frozen in liquid nitrogen for 7 days. Supplementation of gum arabic or egg yolk extenders for ram semen with antioxidants such as cysteine or ascorbic acid has beneficial effects on semen quality after cold storage or cryopreservation. However, supplementation of a 5% gum arabic extender with cysteine at 0.5 or 1 mM concentration or ascorbic acid at 0.5 mM concentration improved the quality of spermatozoa postcryopreservation. It could be concluded that gum arabic is a good alternative for egg yolk in Noemi ram semen extenders. Antioxidants are necessary to support the addition of gum arabic to the extender to help the ram spermatozoa to survive freezing-thawing and oxidative stresses.

Ascorbic acid as antioxidant

Ascorbic acid, as one of the basic exogenous vitamins, is known for its tremendous antioxidant properties. This review has been prepared to show not only the importance of ascorbic acid as a free radical scavenger, but also to summarize its antioxidant action based on other mechanisms, including activation of intracellular antioxidant systems. Ascorbic acid interacts with small molecule antioxidants, including tocopherol, glutathione and thioredoxin, but also can stimulate the biosynthesis and activation of antioxidant enzymes, such as superoxide dismutase, catalase or glutathione peroxidase. Moreover, ascorbic acid promotes the activity of several transcription factors (Nrf2, Ref-1, AP-1), which enables the expression of genes encoding antioxidant proteins. Additionally, it supports the action of other exogenous antioxidants, mainly polyphenols. In this connection, both DNA, protein and lipids are protected against oxidation. Although ascorbic acid has strong antioxidant properties, it can also have pro-oxidant effects in the presence of free transition metals. However, its role in prevention of DNA mutation and cellular apoptosis, especially in relation to cancer cells is controversial.

Antioxidative and Anti-Inflammatory Activity of Ascorbic Acid

Ascorbic acid, as a one of the basic exogenous vitamins, occurs in the body in the form of ascorbate, known for its strong antioxidant and anti-inflammatory properties. The presented review shows not only the importance of ascorbate as a free radical scavenger but also summarizes its antioxidant action based on other mechanisms, including the activation of intracellular antioxidant systems and its effect on the NFκB/TNFα pathway and apoptosis. Ascorbate interacts with small-molecule antioxidants, including tocopherol, glutathione, and thioredoxin; it can also stimulate biosynthesis and the activation of antioxidant enzymes, such as superoxide dismutase, catalase, or glutathione peroxidase. Moreover, ascorbate promotes the activity of transcription factors (Nrf2, Ref-1, AP-1), which enables the expression of genes encoding antioxidant proteins. Additionally, it supports the action of other exogenous antioxidants, mainly polyphenols. In this regard, both DNA, proteins, and lipids are protected against oxidation, leading to an inflammatory reaction and even cell death. Although ascorbate has strong antioxidant properties, it can also have pro-oxidant effects in the presence of free transition metals. However, its role in the prevention of DNA mutation, inflammation, and cell apoptosis, especially in relation to cancer cells, is controversial.

Spermatozoa Survival in Egg Yolk-Based and Soybean-Based Extenders at Ambient and Chilling Temperature in Domestic Turkeys (Meleagris gallopavo)

Populations of many galliform species have declined mainly due to habitat loss and over-hunting, notably the Congo peacock, which has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). The domestic turkey, being a species of least concern, which has been reported to be closely related to peacocks, could serve as a model for the optimization of assisted reproductive technologies for the Congo peacock. This study was aimed at developing a suitable turkey semen extender for artificial insemination in field conditions. Semen was collected using the dorso-abdominal massage technique from seven turkey toms and analyzed. Ejaculates with >70% motility and >80% live spermatozoa were pooled and divided into four aliquots (four treatments). Each of the four treatments was extended in a soybean-based extender or an egg yolk-based extender, with or without L-ascorbic acid. Two liquid preservation protocols (ambient temperature (35 °C) and chilled (4 °C)) were employed, and quality parameters including motility, viability and morphology were evaluated. The results show that the two extenders were similar with regard to semen quality parameters, and L-ascorbic acid supplementation of the turkey semen extenders improved semen quality during liquid storage.

Protective Effect of Chlorogenic Acid on Human Sperm: In Vitro Studies and Frozen-Thawed Protocol

The study evaluated the chlorogenic acid (CGA) antioxidant potential on oxidative stress (OS) induced in vitro in human spermatozoa and during cryopreservation procedure. Swim-up selected spermatozoa were treated with 100 µM CGA, 100 µM H₂O₂ to induce lipid peroxidation (LPO), and with both compounds and the effects on mitochondrial membrane potential (MMP) by JC-1, DNA integrity by acridine orange (AO), and sperm ultrastructure by transmission electron microscopy (TEM), were evaluated. CGA antioxidant activity was assessed by measuring malondialdehyde (MDA) and F₂-isoprostanes (F₂-IsoPs) in the media. The CGA protective activity and the immunolocalization of Phospho-AMPKα (Thr172) were explored in frozen-thawed sperm. CGA was not toxic for sperm motility, DNA integrity and MMP. The increase in MDA (p < 0.05) and F₂-IsoPs (p < 0.001), DNA damage (p < 0.01) and low MMP (p < 0.01) levels after H₂O₂ treatment were reduced in presence of CGA as well as the percentage of broken plasma membranes (p < 0.01) and altered acrosomes (p < 0.01) detected by TEM. Treated frozen-thawed spermatozoa showed increased sperm motility (p < 0.01), DNA integrity (p < 0.01), MMP (p < 0.01), reduced MDA (p < 0.01) and increased sperm percentage with Phospho-AMPKα labelling in the head (p < 0.001). CGA can be used to supplement culture media during semen handling and cryopreservation where OS is exacerbated.

Protective effect of vitamin C and lycopene on the in vitro fertilization capacity of sex-sorted bull sperm by inhibiting the oxidative stress

The fertilization capacity of sex-sorted sperms is seriously decreased, which inhibits its wide application. However, little information is still available about the effect of vitamin C (VC) and lycopene (Lyc) on the fertilization capacity of sex-sorted bull sperm. In this study, the washing medium and fertilization medium of sex-sorted sperm from three bull individuals were supplemented with different concentrations of VC (0, 1 × 10^-3 , 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6  M) or Lyc (0, 1 × 10^-4 , 1 × 10^-5 , 1 × 10^-6 , 1 × 10^-7 ). After washing twice and incubation for 1.5 hr, the malondialdehyde (MDA) level, phosphatidylserine (PS) translocation, membrane potential (Δψm) and IVF (in vitro fertilization) ability of sex-sorted sperm were investigated. For the sex-sorted sperm of bulls A, B and C, 1 × 10^-3  M VC or 1 × 10^-4  M Lyc treatment significantly decreased their MDA levels and PS translocation and increased their Δψm levels and cleavage rates after IVF. When blastocysts were concerned, 1 × 10^-4  M Lyc significantly improved the blastocyst rates and their IFN-tau expression of bulls A and C. In conclusion, supplementation of 1 × 10^-3  M VC or 1 × 10^-4  M Lyc in washing and fertilization medium contributed greatly to improving the fertilization capacity of sex-sorted bull sperm during IVF procedure.

Supplementation of green tea extract (GTE) in extender improves structural and functional characteristics, total antioxidant capacity and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa

The aim of this study was to elucidate the beneficial effects of green tea extract (GTE) in tris citric acid extender on post thaw structural and functional characteristics, DNA fragmentation (%), total antioxidant capacity (TAC, μM/L), lipid peroxidation (LPO, μM/mL) levels and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa. GTE is a acknowledged natural antioxidant, act as a free radical scavenger and protects spermatozoa against oxidative stress. Three mature and donor buffalo bulls were used in this experiment. Two ejaculates were collected per bull on each collection day, followed by initial evaluation for consistency (colour), volume (mL), progressive motility and concentration (x10⁹) and were diluted in five extenders @ 50 x 10⁶/ mL (C = control, no GTE; T1 = treatment 1, GTE 0.1%; T2 = treatment 2, GTE 0.5%; T3 = treatment 3, GTE 0.75% and T4 = treatment 4, GTE1.0%). The experiment was repeated thrice. Data analysis showed that sperm progressive motility (%), plasma membrane integrity (%), supravital plasma membrane integrity (%), viable sperm with intact acrosome (%) and TAC were significantly higher (P < 0.05) in extender supplemented with T4 as compared to control. Furthermore, sperm DNA fragmentation and occurrance of LPO in buffalo bull spermatozoa were significantly lowered in T4 than control. In vitro longevity (%) of spermatozoa was significantly higher in T4 compared to control during 45 and 90 min of incubation at 37 °C. In vivo fertility rate of buffalo bull spermatozoa was significantly higher in T4 compared to control (64.96 vs. 48.40%, P < 0.05). It is concluded that supplementation of tris citric acid extender with 1.0% GTE improved structural and functional characteristics, TAC, in vitro longevity (%) and in vivo fertility, whereas decreased DNA fragmentation and LPO occurrence in buffalo bull spermatozoa after freezing and thawing protocol.

Ameliorative Effect of Ascorbic Acid and Glutathione in Combating the Cryoinjuries During Cryopreservation of Exotic Jack Semen

The present study was designed to study the adverse effects of cryopreservation and evaluation of the cryoprotective effect of reduced glutathione (GSH) and ascorbic acid (AA) supplementation on exotic jack semen in combination or alone. For this, 24 semen samples from four adult and fertile jacks were collected via artificial vagina using an estrus jenny as dummy. After semen collection, the semen was evaluated for various qualitative and quantitative parameters in fresh, cooled, and frozen-thawed semen. The semen pellet was extended with the freezing extender containing either AA (0.9 g/L), GSH (2.5 mM), or combination of both (AA 0.9 g/L + GSH 2.5 mM), and another aliquot was kept as control without adding the antioxidants. The jack semen underwent cryodamage, which was evident by the observation of significant (P < .05) decline in the seminal quantitative parameters at various stages of cryopreservation process. Prefreeze and postthaw semen evaluation revealed that the values of plasma membrane, acrosome integrity, and chromatin integrity were found to be significantly higher (P < .01) in the group of samples supplemented with the combination (0.9 g/L AA +2.5 mM GSH) than AA- and GSH-alone or control groups. Supplementation of antioxidants to the freezing extender improved jack prefreeze and postthaw semen quality with the superiority of GSH over AA alone. From the present study, it was inferred that, exotic jack spermatozoa are susceptible to injuries because of cryopreservation, but these cryo-induced damage can be ameliorated significantly (P < .05) with the use of antioxidants and contribute to the improvement of semen cryopreservation procedures.

Effect of superoxide dismutase, catalase, and glutathione peroxidase supplementation in the extender on chilled semen of fertile and hypofertile dogs

This study investigated the correlation between oxidative stress status and key canine sperm parameters and the effect of addition of a superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) combination in egg yolk tris-citrate glucose (EYT-G) extender on semen during 10 days of storage at 4℃. Ten Boxer dogs were divided into two groups, fertile (F) and hypofertile (H), depending on pregnancy and live birth rate status in the previous year. Semen evaluation was performed on the day of collection (D0) and after 5 (D5) and 10 (D10) days of cooled storage. Sperm motility, kinetic parameters, and DNA integrity were assessed. A correlation between oxidative status and key semen parameters in both F and H groups was observed. Total and progressive motilities were significantly higher in the treated (SOD, CAT, and GPx addition) versus control groups at D10 in both F and H groups, and at D5 in the H group. DNA integrity was significantly higher in both treated groups (H and F) at D5 and D10. In conclusion, the addition of SOD, CAT, and GPx in the extender allows preservation of semen quality for up to 10 days of storage at 4℃ in both fertile and hypofertile dogs.

Antioxidant supplementation, effect on post-thaw spermatozoan function in three sturgeon species

High levels of reactive oxygen species (ROS), which may be associated with reduced sperm quality, can be detected during cryopreservation of sperm of some species. Our objective was to investigate whether the addition of antioxidants to cryopreservation extenders influenced post-thaw sperm characteristics and fertility in Acipenser dabryanus, Acipenser sinensis and Acipenser baerii. Prior to freezing, sperm samples were diluted with a base extender as control or in extender supplemented with catalase (CAT), glutathione (GSH), cysteine (NAC), ascorbic acid (VC) or their paired combinations. Protective concentrations of CAT, GSH and VC in the three species were 25 U/ml, 0.25-0.5 mg/ml and 0.5 mg/ml, respectively. Cysteine showed no protective effect against ROS. The addition of CAT, GSH and VC positively affected either acrosome or membrane integrity of post-thawed sperm in the three species, as well as spermatozoan motility in A. sinensis. The combination of antioxidants did not show a positive synergistic effect. This study suggested that the use of antioxidants in the cryopreservation of sturgeon sperm has potential to decrease intracellular ROS, and consequently preserve acrosome and membrane integrity, as well as spermatozoan motility.

Deep insemination with sex-sorted Cashmere goat sperm processed in the presence of antioxidants

Flow cytometrically sex-sorted sperm have been widely used for improving reproductive management in the dairy industry. However, the industrial application of this technology in other domestic species is largely limited by the lower fertility after insemination. The aim of this study was to investigate effects of antioxidant supplementation during the sex-sorting and freezing process on the quality and functions of sorted sperm from Liaoning Cashmere goats. We tested the effects of antioxidant supplementation during sex-sorting and freezing process, including ascorbic acid-2-glucoside AA-2G, glutathione, melatonin and vitamin C (VC), on the quality and functions of sex-sorted fresh and frozen-thawed sperm. Based on these experiments, we performed deep insemination with sex-sorted sperm using our improved strategy, in comparison to unsorted sperm. In Experiment 1, compared with control group and other antioxidants, AA-2G supplementation significantly alleviated the degradation of motility and viability of fresh sperm after sorting and showed the highest percentage of sperm with normal morphology. In addition, AA-2G supplementation showed an evident protection against the sorting process-induced membrane and acrosome damage. In Experiment 2, AA-2G supplementation was most effective in protecting motility, while melatonin supplementation appears to facilitate the degradation of quality of frozen-thawed sex-sorted sperm. In Experiment 3, we performed deep insemination with sperm that were sorted and frozen in the presence of AA-2G and obtained a satisfying pregnancy rate comparable to that from unsorted sperm. The results showed that AA-2G supplementation efficiently protects quality and function of both fresh and frozen-thawed sex-sorted sperm of Cashmere goats, thus obtaining a satisfying pregnancy outcome.

ÁCIDO ASCÓRBICO NO DILUIDOR PARA CRIOPRESERVAÇÃO DE SÊMEN CAPRINO

Resumo Objetivou-se determinar o efeito e o melhor nível de inclusão de ácido ascórbico em meio diluidor TRIS-Gema para criopreservação de sêmen caprino. Foram utilizados cinco ejaculados de três bodes da raça Anglo Nubiana. Cada ejaculado foi dividido em quatro alíquotas de 200 µL, compondo quatro tratamentos: um sem adição de ácido ascórbico (controle) e os demais com 0,0528; 0,1056 e 0,1584mg/mL de ácido ascórbico no diluidor TRIS-Gema. Avaliaram-se motilidade espermática progressiva e vigor espermático pós-diluição, pós-resfriamento e pós-descongelamento; integridade de membrana (HOST); integridade acrossomal e teste de termorresistência lento (TTR). Os dados foram submetidos à Análise de Regressão a 5% de probabilidade. Não houve diferença para motilidade progressiva e para vigor espermático, repectivamente, na pós-diluição; pós-resfriamento e pós-descongelamento, assim como para os testes complementares HOST e após 120 minutos do TTR, para motilidade e vigor, no pós-descongelamento (P>0,05). Houve comportamento quadrático com a inclusão do ácido ascórbico para integridade acrossomal (61,58%), com nível ótimo de 0,1006mg/mL de ácido ascórbico (P<0,05). A inclusão de 0,1006mg/mL de ácido ascórbico no diluidor TRIS-Gema melhorou a integridade acrossomal durante o processo de criopreservação, podendo ser uma alternativa na composição dos diluidores seminais caprinos.

Royal jelly supplementation in semen extender enhances post-thaw quality and fertility of Nili-Ravi buffalo bull sperm

Two experiments were conducted to evaluate the effect of royal jelly (RJ) on post-thaw sperm quality, in vitro and in vivo fertility rate of cryopreserved buffalo bull sperm. The semen was collected from three mature regular donor buffalo bulls, ejaculates were pooled and semen evaluated initially. In Experiment 1, the ejaculates were extended in tris-citric acid diluter supplemented with different RJ concentrations (0, 0.05, 0.1, 0.2, 0.3 or 0.4%). The diluted semen was cooled to 4°C, packaged into 0.5 mL straws and frozen using standard procedure. The straws were thawed and assessed for sperm progressive motility, viability, plasma membrane, acrosome, and chromatin integrity. The results indicated that sperm progressive motility was significantly greater (P<0.05) in 0.05, 0.1, 0.2 and 0.3% RJ than 0.4% RJ supplemented and control groups. The sperm viability, plasma membrane and acrosome integrity were significantly improved (P<0.05) in 0.1% RJ supplemented group the compared to other treatment groups. In Experiment 2, cryopreserved sperm with 0.1% RJ supplementation and control (without RJ supplementation) were used to observe the in vitro fertilizing potential and in vivo fertility. In vitro fertilization method was applied to assess the cleavage rate; whereas, AI was performed in buffalo during in vivo fertility trial. The buffaloes were inseminated 12h after standing estrus and pregnancy diagnosis was performed through ultrasonography. The results revealed that the cleavage rate was higher (P<0.05) in 0.1% RJ as compared to control group. However, the pregnancy rate was similar (P>0.05) between 0.1% RJ supplemented and control groups. It is concluded that supplementation of RJ in freezing extender can improve the cryosurvival rate and in vitro fertilizing capacity of buffalo bull sperm.

Effect on post-cryopreserved semen characteristics of Holstein bulls of adding combinations of vitamin C and either catalase or reduced glutathione to Tris extender

This study was undertaken to investigate the influence of adding combinations of vitamin C to Tris extender with either catalase or reduced glutathione on post-cryopreserved semen characteristics of Holstein bulls for different preservation periods (cooling at 5°C, 48 h, 1, 2 and 3 months post cryopreservation, PC). Seven Holstein bulls of 2.5-3 years of age were used in this experiment. Semen was collected via artificial vagina in one ejaculate per bull per week for the 7 week experimental period. Pooled semen was equally divided into three treatments using Tris extender. Combinations of vitamin C (2.5mM) were added with either catalase (100 IU/ml, T2) or reduced glutathione (2mM, T3) to Tris extender and comparisons in response were made with the control group (Tris extender, T1). Individual sperm motility (IM), viability (V), plasma membrane integrity (PMI), and acrosome integrity (AI) were assessed during all periods of the study along with Malondialdehyde (MDA) concentrations and freezing ability. The IM was greater (P ≤ 0.01) in the T2 as compared with the T1 group at all periods of the study. Furthermore, the IM were greater (P ≤ 0.01) in the T3 as compared with the T1 group at the 48 h time period and at 3 months PC. The V, PMI and AI were greater (P ≤ 0.01) in T2 and T3 as compared with the T1 group at all the experimental periods. The MDA was greater (P ≤ 0.01) in the T2 as compared with the T1 group at 3 months PC. In conclusion, there was improved semen quality if semen of Holstein bulls was collected and stored in combinations of vitamin C with either catalase (T2) or reduced glutathione (T3) being added to Tris extender.

Sperm Storage in the Female Reproductive Tract

The capacity for sperm storage within the female reproductive tract occurs widely across all groups of vertebrate species and is exceptionally well developed in some reptiles (maximum duration seven years) and fishes (maximum duration >1 year). Although there are many reports on both the occurrence of female sperm storage in diverse species and its adaptive benefits, few studies have been directed toward explaining the mechanisms involved. In this article we review recent findings in birds and mammals in an effort to develop hypotheses that could be translated into research applications in animal breeding technologies. There are pockets of evidence to suggest that the local epithelial cells, sometimes arranged as sperm storage tubules, can respond to spermatozoa by producing heat shock proteins as well as providing an environment rich in antioxidants. Moreover, the local immune system seems to tolerate the arrival of spermatozoa, while retaining the ability to combat the arrival of infectious microorganisms.

Sperm cryopreservation update: Cryodamage, markers, and factors affecting the sperm freezability in pigs

Cryopreservation is the most efficient method for long-term preservation of mammalian sperm. However, freeze-thawing procedures may strongly impair the sperm function and survival and thus decrease the reproductive performance. In addition, the sperm resilience to withstand cryopreservation, also known as freezability, presents a high individual variability. The present work summarizes the principles of cryoinjury and the relevance of permeating and nonpermeating cryoprotective agents. Descriptions about sperm cryodamage are mainly focused on boar sperm, but reference to other mammalian species is also made when relevant. Main cryoinjuries not only regard to sperm motility and membrane integrity, but also to the degradation effect exerted by freeze-thawing on other important components for sperm fertilizing ability, such as mRNAs. After delving into the main differences between good and poor freezability boar ejaculates, those protein markers predicting the sperm ability to sustain cryopreservation are also mentioned. Moreover, factors that may influence sperm freezability, such as season, diet, breed, or ejaculate fractions are discussed, together with the effects of different additives, like seminal plasma and antioxidants. After briefly referring to the effects of long-term sperm preservation in frozen state and the reproductive performance of frozen-thawed boar sperm, this work speculates with new research horizons on the preservation of boar sperm, such as vitrification and freeze-drying.

Effect of Conjugated Linoleic Acid on Boar Semen Quality After Long-term Refrigeration at 17°C

In this study, the effect of conjugated linoleic acid (10 trans, 12 cis) (CLA) on refrigerated boar sperm quality parameters up to 14 days at 17°C was assessed. Semen was extended in Androhep and divided into four treatments supplemented with CLA (25, 50, 100 and 200 μm) and control group, then kept for 2 h at 22°C. Afterwards an aliquot of each treatment was removed, and mitochondrial activity, viability, lipid membrane peroxidation (LPO) and stability of the sperm plasma membrane were assessed by flow cytometry. The remaining extended semen was maintained at 17°C until 336 h, repeating the same analysis every 48 h. Regarding percentage of live spermatozoa, no statistical differences were observed among treatments up to 96 h. After this time, viability decreased significantly (p < 0.05) for CLA concentrations of 100 and 200 μm. Despite these results, there was an individual response to CLA. Although in the control group, the boar A presented better results when compared with the other boars, especially at concentrations of 50 and 100 μm boar B showed significantly higher results (p < 0.05). Supplementation with CLA improved (p < 0.05) LPO, but not the mitochondrial membrane potential of sperm. The highest two CLA concentrations showed to be toxic for sperm as all results were lower than the observed for the control. In conclusion, CLA at 50 μm seems to be an efficient concentration for reducing the oxidative stress, decreasing LPO, maintaining viability, membrane stability and mitochondrial potential on refrigerated boar spermatozoa.

The effects of different levels of vitamin E and vitamin C in modified Beltsville extender on rooster post-thawed sperm quality

Oxidative damage of sperm by means of reactive oxygen species generated by the cellular components of semen is one of the main reason of declined motility and fertility of sperm during the freeze-thawing process. This study was conducted to determine the influence of vitamin C and vitamin E on rooster post-thawed sperm motility, viability and malondialdehyde (MDA) level. Semen samples from 10 sexually-mature Ross 308 breeder roosters were collected and pooled, divided into nine equal parts and diluted with modified Beltsville extender containing with no antioxidants (control), or containing 100 (C100), 200 (C200), 400 (C400), 800 (C800) µg/mL vitamin C, and 2 (E2), 5 (E5), 10 (E10) and 15 (E15) µg/mL vitamin E. After thawing, total and progressive sperm motility, sperm viability and semen MDA level were assessed. The results shown that C200 and E5 extenders resulted in higher total motility (p < 0.05) compared to other extenders, with exception of E10 extender. Progressive motility was higher in E5 extender (p < 0.05) compared to other extenders, with exception of C200 and E10 extenders. Also, C200 and E5 extenders resulted in higher viability of post-thawed spermatozoa (p < 0.05) compared to other extenders. Finally, the results showed that MDA level was lower in C100 and C200 extenders compared to other extenders (p < 0.05), with exception of E5 extender. In conclusion, the results of the present study demonstrate that C200 and E5 can improve the function of post-thawed rooster spermatozoa.

Effect of butylated hydroxytoluene (BHT) on the cryopreservation of common carp (Cyprinus carpio) spermatozoa

The aim of the present study was to test the effects of butylated hydroxytoluene (BHT) on the cryopreservation of common carp spermatozoa. BHT is widely used in the cryopreservation of the spermatozoa of different animal species and successfully sustains the characteristics of spermatozoa during freezing and thawing, but it has not previously been used with fish. After sampling, common carp spermatozoa were diluted with an extender composed of modified Kurokura's extender, 10% DMSO, and 10% egg yolk containing 0.0001, 0.001, 0.01, 0.1, 1, 2.5, 5, or 10mM BHT and subsequently frozen in liquid nitrogen. The post-thaw spermatozoa characteristics (i.e., progressive motility percentage (%), duration of progressive motility (s), fertilization rate (%), and eyed-eggs rate (%)) were evaluated and compared with those of the control group. There were significant increases in the percentage of progressive motility and the duration of progressive motility at the concentrations of 0.1 and 0.001mM BHT (P<0.05). The duration of post-thawed spermatozoa progressive motility at 0.001mM BHT was significantly greater than that of the other groups (39.6±0.4s, P<0.05), and the fertilization rates and eyed-eggs rates were also higher following the 0.1 and 1mM BHT treatments. BHT at concentrations of more than 1mM caused sperm immobility during the preparatory stages of the sperm freezing. We concluded that 0.001-0.1mM BHT can be beneficial for the cryopreservation of common spermatozoa.