Benefits of TEMPOL on ram semen motility and in vitro fertility: a preliminary study

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 Strategic Supplementation of Dietary By-Pass Linseed Oil on Fertility and Milk Quality in Sarda Ewes

The aim of the present study was to assess whether the strategic supplementation of bypass LO can enhance reproductive indexes—fertility, lambing rate, and prolificacy—in dairy Sarda ewes at the end of lactation. To assess whether LO supplementation leads to the adsorptions of PUFAs and their subsequent utilization by the body tissues, milk composition and fatty acid content were analyzed. Forty-eight ewes were assigned to the following groups: the control group (CT; N = 24), fed with a control diet without LO; and the treatment group (LO; N = 24), fed with a diet supplemented with LO (10.8 g/ewe/day). Both diets had similar crude protein and energy levels and were offered for 38 days (−21 to +17 days after artificial insemination). The trial included an adaptation period (7 days) followed by a regular supplementation (31 days) period. Estrus synchronization was induced in all the ewes using an intravaginal sponge and equine chorionic gonadotropin. Fifty-five hours after pessaries withdrawal, all ewes were inseminated using the cervical route and fresh semen. Cholesterol (p < 0.01), high-density lipoprotein (p < 0.001), and triglyceride (p < 0.05) levels in plasma were higher in the LO group. Plasmatic levels of non-esterified fatty acids were lower in the LO group after the end of the supplementation period (p < 0.05). Milk unsaturated fatty acids (UFAs), monounsaturated fatty acids (MUFAs), total polyunsaturated fatty acids (PUFAs), PUFAs omega 3 (PUFAs-ω3) and 6 (PUFAs-ω6), and trans fatty acids were higher in the LO group (p < 0.001), while saturated fatty acids (SFAs) were higher in the CT group during the supplementation period (p < 0.001). Three days after the end of the supplementation period, the content of milk UFAs (p < 0.05), PUFAs (p < 0.001), MUFAs, and PUFAs-ω6 (p < 0.01) were still higher in the LO group. whereas SFA was higher in the CT group (p < 0.01). There was no difference between groups in terms of ovulation rate, progesterone levels in plasma, fertility rate, prolificacy, and total reproductive wastage. However, the total area of luteal tissue was higher in the LO group (p < 0.01). Results obtained demonstrated that LO supplementation exerts a positive role in corpus luteum size at the onset of the peri-implantation period in Sarda dairy ewes. Additionally, the results obtained in the present study showed that the use of dietary bypass LO affects lipid metabolites in plasma and milk fatty acid profiles, demonstrating the ALA uptake by body tissues.

Effect of tempol and straw size on rooster sperm quality and fertility after post-thawing

The aim of the present study was to investigate the effects of tempol and straw size on rooster sperm post-thaw quality and fertility. Rooster semen was cryopreserved in Lake extender containing 0 (control), 5, 10, 15 and 20 μM tempol (in two different straw size, 0.25 and 0.5). The percentage of total and progressive sperm motility, VAP and VSL increased in the 10 µM tempol group. Moreover, 10 µM tempol led to lower ROS compared to other groups. The lowest percentage of apoptotic-like changes was detected when the extender was treated with 10 µM of tempol. The minimum ROS was observed in the group treated with 0.5 straw size. Straw size did not have any significantly effect on GPx and SOD activities and TAC of frozen-thawed sperm. The highest significant percentage of fertility and hatching rate were observed in 10 µM of tempol. The results of the present study showed that supplementation of the Lake cryopreservation medium with 10 µM tempol improved cryo-survival. Also, the results of the present study suggested that Lake cryopreservation medium with 0.5-ml straw may perhaps be an appropriate method to improve the quality and fertility post-thawed rooster sperm.

The necessity of antioxidant inclusion in caprine and ovine semen extenders: A systematic review complemented with computational insight

The inclusion of antioxidants (AOXs) has been proposed in various protocols to conserve the normal physiology of spermatozoa during (cryo) preservation. The main aim of this review was to understand the necessity of AOXs inclusion in semen extenders of caprine and ovine semen samples and to decipher physico-chemical space of AOXs used in semen extenders till now. A total 27 full-text relevant articles were finally discussed here. This systematic review showed that the inclusion of AOXs may improve the success of semen cryopreservation although at least three studies could not support this finding. AOXs have been not added after assaying total antioxidant capacity of the sample of interest, and this is principal measurement bias of all papers. Furthermore, no rational dose-response curve and precise posology have been considered in comparable studies. Furthermore, new methodologies are requested to detect the oxidative status of semen specimens before AXOs fortification and new methodologies like imaging are also needed to detect various injuries of sperms during semen (cryo)preservation. Defining computational chemical and physical spaces of AOXs which used in semen (cryo)preservation would be an interdisciplinary effort to hasten deciphering epoch-making compounds. In conclusion, more in-depth analytical, toxicological and pharmacological methodologies should be pursued in supplementation or addition of AOXs during caprine and ovine semen (cryo)preservation after determining the oxidative status of semen samples.

Effect of olive-derived antioxidants (3,4-dihydroxyphenylethanol and 3,4 dihydroxyphenylglycol) on sperm motility and fertility in liquid ram sperm stored at 15°C or 5°C

The aim of the present study was to evaluate the effect of the addition of two olive oil-derived antioxidants, hydroxytyrosol (3,4-dihydroxyphenylethanol, HT) and 3,4-dihydroxyphenylglycol (DHPG), on ovine semen during liquid storage at 5°C and 15°C. Semen was collected, pooled, diluted and then divided into aliquots supplemented with different concentrations (5 μg/ml, 10 μg/ml, 50 μg/ml and 100 μg/ml) of HT, DHPG and a mixture (MIX) of both antioxidants. Sperm motility characteristics were assessed in the different samples at 0, 6, 24, 48, 72 and 96 hr after cooling, and a fertility trial was also conducted. The results showed that the antioxidant addition did not significantly improve total and progressive motility in ovine cooled sperm maintained at 15° or 5°C. However, in samples stored at 5°C, LIN (48, 72, 96 hr), STR (0 hr) and WOB (0, 48, 72, 96 hr) values significantly decreased in comparison with control treatment when high antioxidant concentrations were added (MIX100 or HT100). When samples were maintained at 15°C, MIX50 showed significantly higher VCL values than the control treatment after 6 hr cooling, and MIX100 showed significantly lower VCL values at 96 hr after cooling. According to the artificial insemination trial, no significant differences were observed when antioxidants were added. In conclusion, the use of HT and DHPG showed small impact in sperm motility and fertility was not affected (nor detrimentally nor positively) when insemination was carried out using antioxidant-supplemented liquid sperm.

Reduced glutathione addition improves both the kinematics and physiological quality of post-thawed red deer sperm

The potential protective effect of reduced glutathione (GSH) and trolox (TRX), an analogue of vitamin E, supplementation during in vitro culture (2h, 39°C) of electroejaculated frozen/thawed red deer sperm was investigated. Cryopreserved sperm were thawed and incubated with no additive (Control) and 1mM or 5mM of each antioxidant to find out whether these supplementations can maintain the sperm quality, considering the use of thawed samples for in vitro techniques such as in vitro fertilisation (IVF), sperm sex sorting or refreezing. The effect of GSH on sperm motility was positive compared to TRX which was negative (P<0.001). After 2h of incubation at 39°C, use of GSH improved motility while TRX supplementation reduced sperm motility compared with Control samples without antioxidant. Use of TRX at both concentrations (1 and 5mM; TRX1 and TRX5) resulted in lesser percentages of apoptotic sperm (12.4±1.1% and 11.7±0.9%) than GSH1, GSH5 (15.2±1% and 14.6±1.1%) and Control samples (16.9±1.2%) (P<0.001). Use of GSH at both concentrations (1 and 5mM) resulted in greater mitochondrial activity as compared with findings for the Control, TRX1 and TRX5 groups. Results of this study indicate that GSH is a suitable supplement for electroejaculated red deer sperm. It would be necessary to conduct fertility trials (in vivo and in vitro), to assess whether GSH supplementation of thawed red deer sperm could improve fertility rates.

Effect of several antioxidants on thawed ram spermatozoa submitted to 37°C up to four hours

Thawed ram spermatozoa were incubated at 37°C in the presence of dehydroascorbic acid (DHA), TEMPOL (TPL), N-acetyl-cysteine (NAC) and rutin (RUT), at 0.1 and 1 mm, in order to test their effects on sperm physiology. Cryopreserved spermatozoa from four rams were thawed, pooled, washed and incubated in TALP-Hepes with 1 mm or 0.1 mm of each antioxidant, performing a replicate with induced oxidative stress (Fe(2+) /ascorbate). Motility (CASA), viability and mitochondrial membrane potential (flow cytometry) were analysed at 2 and 4 h. Lipoperoxidation (MDA production), intracellular reactive oxygen species (ROS) and DNA status (TUNEL) were analysed at 4 h. Antioxidants, except DHA 0.1 mm, decreased motility and kinematic parameters, but had little effect on viability or mitochondrial activity. Except 1 mm DHA, the antioxidants reduced ROS at 4 h. Moreover, NAC 1 mm, rutin and TEMPOL reduced ROS and DNA damage in the presence of oxidative stress. N-acetyl-cysteine, rutin 1 mm and TEMPOL reduced lipoperoxidation in the presence of oxidative stress. However, DHA did not affect lipoperoxidation. At 1 mm, DHA increased DNA damage in the absence of oxidative stress. Dehydroascorbic acid effects could arise from spermatozoa having a low capacity for reducing it to ascorbic acid, and it may be tested in the presence of other antioxidants or reducing power. Future research should focus in testing whether the inhibition of motility observed for NAC, rutin and TEMPOL is reversible. These antioxidants might be useful at lower temperatures (refrigerated storage or cryopreservation) when their protective effects could be advantageous.

Effect of different diluents on goat semen fertility

Skim milk (SM) is considered to be the most widely employed extender for goat sperm used for artificial insemination (AI). However, the fertilizing life span of sperm stored in milk or milk-based extenders does not exceed 12h. Besides some seminal plasma components, such as a protein fraction from the goat bulbourethral gland secretion (SBUIII), interacts with some milk fractions and inhibits the spermatozoa motility. The aim of this study was to prolong the survival of buck semen and its fertility. Buck ejaculates were diluted to a final concentration of 100x10(6)spermatozoa/ml with three different diluents: SM, TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) and TEMPOL+hyaluronic acid (TEMPOL+HA). At 7h from dilution 42 goats were inseminated with semen diluted with SM (short-term semen) while after storage for 24h, 44 and 45 goats were inseminated with semen diluted with TEMPOL and TEMPOL+HA (long-term storage), respectively. At day 50 from AI the percentages of pregnant goats were 71.4% (30/42) with SM, 61.4% (27/44) with TEMPOL and 48.8% (22/45) with TEMPOL+HA, with significant differences between SM and TEMPOL+HA. The kidding rate was 66.7% (28/42) with SM diluent, 61.4% (27/44) with TEMPOL and 48.8% (22/45) with TEMPOL+HA, without significant differences among treatment groups. In conclusion, it is possible to maintain good fertility in goats after AI with semen stored for 24h in TEMPOL.

Effects of solid storage of sheep spermatozoa at 15°C on their survival and penetrating capacity

This study was designed to evaluate the possible benefits of adding gelatin to a standard milk extender, for solid storage of sheep semen at 15 degrees C. Solid storage was assessed in terms of effects on sperm motility and membrane integrity up to 2 days (Study 1), and on in vitro penetration capacity after storage for 24h (Study 2). In both studies, semen was diluted in CONTROL (standard milk extender) and GEL (1.5 g gelatin/100ml extender) diluents to a final concentration of 400 x 10(6)sperm/ml. In Study 1, semen samples were stored at 15 degrees C, and sperm quality variables analyzed after 2, 24 and 48 h of storage. Motility and viability values were significantly lowered using the liquid compared to the gel extender for all storage periods, except for motility after 2h of storage, whose values were similar. After 2h of incubation at 37 degrees C, motile cell percentages and membrane integrity were significantly lower in the CONTROL group than in the GEL group for all storage periods. In Study 2, in vitro matured lamb oocytes were randomly divided into three groups and fertilized with CONTROL diluted semen stored for 2h or 24h, or with GEL diluted semen stored for 24h. After co-incubation, oocytes were evaluated for signs of penetration. Storage of semen in the GEL diluent for 24h gave rise to increased in vitro fertilization rates in comparison with the CONTROL diluent. Our findings indicate that the solid storage at 15 degrees C of ram spermatozoa by adding gelatin to the extender leads to improved survival and in vitro penetrating ability over the use of the normal liquid extender. A solid diluent could thus be a useful option for the preservation of fresh ovine semen for extended periods.