A single administration of carbetocin before electroejaculation increases the insemination doses produced from each ejaculate in rams.

The aim of the study was to determine the effect of carbetocin administration (a long-acting analog of oxytocin) 20 or 10 min before electroejaculation (EE) on the duration of semen collection procedure, quantitative and qualitative characteristics of the ejaculate, and stress biomarkers in rams. Semen was collected from 12 Corriedale rams (age, 2.5-5.5 years old) with EE, in a Latin-square design, administrating carbetocin (0.2 mg/100 kg of body weight i.v.) 20 or 10 min before EE, or without carbetocin administration (CB-20, CB-10, and CON treatments, respectively). Each treatment was applied to different rams every 3-4 days, allowing all the rams to receive all three treatments. Carbetocin administered 20 or 10 min before EE increased the number of sperm ejaculated (P = 0.01), the semen concentration (P = 0.02), the number of insemination doses collected in a single collection (P = 0.01), and the number of insemination doses collected/electrical pulses administered (P = 0.05) compared to control rams. Carbetocin administered 20 or 10 min before semen collection prolonged the time required for EE and the number of pulses administered during EE compared to CON rams (P < 0.03 for both). The CB-10 rams required the administration of more electrical pulses during ejaculation than CON rams (P = 0.001), and CB-20 treatment tended to require more electrical pulses than CON rams (P = 0.06). The volume of the ejaculate was greater in CB-10 than in CON rams (P = 0.01), and that of CB-20 treatment tended to be greater than CON rams (P = 0.08). The percentage of sperm with intact membrane was greater in CB-20 than in CON rams (P = 0.01). Total protein, albumin, and globulin concentrations were lower immediately after carbetocin administration 20 or 10 min before EE. The treatments did not affect cortisol concentration, glycemia, rectal and surface temperatures, heart rate, and facial expressions. Carbetocin administration before EE of rams improved the quantitative and qualitative characteristics of the ejaculate, duplicating the number of insemination doses collected. It can be a promising treatment to obtain a greater quantity of doses to inseminate with a lower frequency of semen collections, reducing the negative impacts of EE on animal welfare.

Efficient and repeatable in vitro fertilization in rabbits.

Rabbits constitute an interesting model to understand gamete interaction and test novel Artificial Reproductive Techniques, but in vitro fertilization (IVF) is particularly problematic in this species. We have conducted a series of experiments to develop a consistent IVF technique. Initially, we checked viability, acrosome integrity, capacitation and motility in ejaculated sperm purified by a density gradient and incubated at different times in three different media: Tyrode's Albumin Lactate Pyruvate (TALP), human tubal fluid (HTF), and Brackett and Oliphant (BO). Total and progressive motility at 10-24 h and linearity from 3 h onwards was significantly higher in BO medium compared to TALP and HTF. Subsequently, cumulus-oocyte complexes (COCs) collected 10 h after induction of ovulation were incubated with sperm in TALP, HTF or BO for 18 h with or without performing sperm pre-incubation for 6 h. Pronuclear formation rate at 18 h was significantly higher in BO compared to other media (∼84 % vs. 17-22 %) and was not improved by pre-incubation. As COCs recovery rate was low at 10 h after induction of ovulation, COCs were collected at 12 h and co-incubated with sperm in BO. Pronuclear formation rate was similar than those obtained in COCs collected at 10 h (∼85 %), and when embryos were allowed to develop in vitro, the protocol yielded high cleavage and blastocyst rates (91 and 59 %, respectively). In conclusion, ejaculated rabbit sperm purified in a density gradient fertilize efficiently COCs collected at 12 h in BO medium.

Review: Sperm cryopreservation in wild small ruminants: morphometric, endocrine and molecular basis of cryoresistance.

Reproductive technologies can help to protect wild ruminant species from becoming extinct. In addition, the decline in some wild game species has also raised interest in reproductive technologies to increase the number of animals that can be produced. Most biobanking efforts have focused on developing effective protocols for preserving sperm, oocytes, and embryos. Cryopreservation of sperm remains the least invasive method and the cheapest procedure for germplasm storage. Over the last few years, several reproductive biotechnologies have been developed beyond the conventional freezing of spermatozoa. These include ultra-rapid freezing techniques. Nevertheless, fertility results after artificial insemination using frozen-thawed spermatozoa are not always acceptable in wild small ruminants. Moreover, these technological efforts have met variable success related to the sample's origin (epididymal retrieved postmortem or ejaculated) and the season of sperm sample collection and storage. Epididymal sperm shows higher cryoresistance than ejaculated sperm. Changes in sperm proteome between epididymal and ejaculated sperm seem to contribute to this different cryotolerance. The role of endocrine status has been studied in some wild species to better understand the underlying mechanism of the annual variation in ruminant sperm cryoresistance. Seasonal changes in testosterone and prolactin are involved in sperm cryoresistance; sperm recovery and cryopreservation are recommended around the end of the rutting season, when good quality sperm samples can still be obtained, testosterone levels have already decreased, and prolactin concentrations remain low. The mechanisms of hormone action on sperm freezability are not well known. Still, it has been suggested that testosterone affects cell proliferation in the testis, during spermatogenesis, and membrane properties of sperm cells during their transit through the reproductive tract, which might influence their cryotolerance. Recent studies have revealed that the expression of aquaporins in the sperm cells of small wild ruminants could also be involved in the androgen-related seasonal variation of sperm cryoresistance. Along with epididymal and ejaculated spermatozoa, the cryopreservation of testicular tissue may provide a suitable source of male gametes, becoming an alternative for establishing germplasm banks when semen cannot be collected for whatever reason.

Use of the flavonoid taxifolin for sperm cryopreservation from the threatened Bermeya goat breed.

Taxifolin is a plant flavonoid effective as an antioxidant. This study aimed to assess the effect of adding taxifolin to the semen extender during the cooling period before freezing on the overall post-thawing sperm variables of Bermeya goats. In the first experiment, a dose-response experiment was performed with four experimental groups: Control, 10, 50, and 100 µg/ml of taxifolin using semen from 8 Bermeya males. In the second experiment, semen from 7 Bermeya bucks was collected and extended at 20 °C using a Tris-citric acid-glucose medium supplemented with different concentrations of taxifolin and glutathione (GSH): control, 5 µM taxifolin, 1 mM GSH, and both antioxidants. In both experiments, two straws per buck were thawed in a water bath (37 °C, 30 s), pooled, and incubated at 38 °C. Motility (CASA) was assessed at 0, 2, and 5 h, and sperm physiology was assessed at 0 and 5 h by flow cytometry (viability, intact acrosome membrane, mitochondria membrane potential, capacitation, intracellular reactive oxygen species -ROS-, mitochondrial superoxide, and chromatin status). In experiment 2, an artificial insemination trial (AI) was included with 29 goats for testing the taxifolin 5-µM treatment on fertility. Data were analyzed with the R statistical environment using linear mixed-effects models. In experiment 1 and compared to the control, T10 increased progressive motility (P < 0.001) but taxifolin decreased total and progressive motility at higher concentrations (P < 0.001), both post-thawing and after the incubation. Viability decreased post-thawing in the three concentrations (P < 0.001). Cytoplasmic ROS decreased at 0 and 5 h at T10 (P = 0.049), and all doses decreased mitochondrial superoxide post-thawing (P = 0.024). In experiment 2, 5 µM taxifolin or 1 mM GSH (alone or combined) increased total and progressive motility vs. the control (P < 0.01), and taxifolin increased kinematic parameters such as VCL, ALH, and DNC (P < 0.05). Viability was not affected by taxifolin in this experiment. Both antioxidants did not significantly affect other sperm physiology parameters. The incubation significantly affected all the parameters (P < 0.004), overall decreasing sperm quality. Fertility after artificial insemination with doses supplemented with 5 µM taxifolin was 76.9% (10/13), not significantly different from the control group (69.2%, 9/13). In conclusion, taxifolin showed a lack of toxicity in the low micromolar range and could benefit goat semen cryopreservation.

Cryopreservation of testicular tissue from the dog (Canis familiaris) and wild boar (Sus scrofa) by slow freezing and vitrification: Differences in cryoresistance according to cell type.

Sperm cryopreservation is the most common procedure used to establish germplasm banks for endangered species - but sometimes sperm cells cannot be obtained. In such cases, freezing testicular tissue may be the only option. The testes contains germ cells at different stages of differentiation, including spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa, among which differences in cryoresistance might be expected. The present work compares the viability and DNA integrity of 'rounded' cells, and of elongated spermatids and spermatozoa, from the dog and wild boar, following the cryopreservation of testicular tissue by slow freezing or vitrification. Cell viability was analyzed by PI/SYBR14 staining, and DNA integrity via the TUNEL technique. For wild boar, no significant differences were seen between the two methods with respect to the percentage of viable cells, nor in the percentage of cells with DNA damage. In the dog, the percentage of viable rounded germ cells (65.0 ± 2.4%) was higher (P < 0.05) after vitrification than after slow freezing (45.1 ± 6.7%). No difference was found between the two methods in terms of the viability of elongated cells. For rounded cells, the percentage of intact DNA was greater (P < 0.05) after vitrification (90.5 ± 2.1%) than after slow freezing (42.6 ± 11.0%), while for elongated spermatids and spermatozoa it was higher (P < 0.05) after slow freezing (66.9 ± 6.1%) than after vitrification (50.7 ± 4.5%). Thus, the response to cryopreservation is cell type-, cryopreservation type-, and species-dependent. Vitrification would appear to be the most appropriate method for preserving dog testicular tissue given the associated high cell viability and low degree of DNA fragmentation, while in wild boar, either method might be used.

Freezing chicken semen: Influence of base medium osmolality, cryoprotectants, cryoprotectant concentration, and cooling rate on post-thaw sperm survival.

A classical chicken semen diluent (Lake's 7.1 diluent) was modified to have lowered osmolalities (ranging from 290 to 410 mOsm/kg). The modified medium with physiological osmolality of 325 mOsm/kg allowed cold storage of fresh semen for several days with very little loss of membrane integrity and motility, while high osmolalities inhibited motility. This modified medium was then used as base for freezing medium to test effects of the type and concentration of cryoprotective agent (CPA), and the cooling rate (CR). A number of CPAs (methylformamide, methylacetamide, dimethylformamide (DMF), dimethylacetamide (DMA), diethylformamide, and propylene glycol) were first compared by freezing semen with 0.6 mol/l of the respective CPA at a cooling rate of 250 °C/min. Post-thaw motility and membrane integrity were highest with DMA and DMF. Finally, in more detailed factorial experiments, semen from individual cocks or pooled semen was frozen using CRs of 4, 50, 250, and 440 °C/min and DMA concentrations ([DMA]) of 0.4, 0.6, 1.0, and 1.5 mol/l. Straws from each semen sample x treatment combination were divided for semen assessment at three different research groups for sperm motility, membrane integrity, kinked tails, and DNA fragmentation, using microscopy, computer assisted motility analysis, and flow cytometry. There were clear effects of both CR and [DMA] and their interaction. CRs 50 and 250 °C/min gave best post-thaw sperm performance. Higher DMA concentrations gave better post-thaw membrane integrity, but concentrations above 1.0 mol/l can decrease sperm velocity or even inhibit sperm motility. Therefore [DMA] may best be 0.6-1.0 mol/l at a CR of 50-250 °C/min.

BoviPure® density-gradient centrifugation procedure enhances the quality of fresh and cryopreserved dog epididymal spermatozoa.

BoviPure® is a salt solution containing colloidal silica particles coated with silane used to select sperm (e.g., ruminants) by density-gradient centrifugation (DGC). This research assessed the suitability of the BoviPure-DGC and swim-up methods for selecting dog epididymal sperm in fresh, chilled and frozen-thawed samples on post-treatment sperm quality. Sperm samples (n = 60 epididymides) were recovered by retrograde flushing from thirty orchiectomized adult dogs. Thereafter, 20 sperm pools, containing sperm aliquots of three randomly selected animals, were used for chilling (at 5 ºC for 24 h) and freezing (in liquid nitrogen vapors). Sperm selection by BoviPure-DCG and swim-up was performed in both individual and pooled samples, including non-selected samples as controls. Overall, after BoviPure-DGC selection a higher sperm retrieval rate was obtained than the swim-up selection in both individual (P < 0.05) and pooled (P < 0.01) samples. BoviPure-DGC improved (P < 0.05) the total (TM) and progressive (PSM) sperm motilities, curvilinear (VCL) and straight-line (VSL) velocities, linearity (LIN), wobble (WOB), beat-cross frequency (BCF), and integrity of plasmatic (IPM) and acrosomal (IAM) membranes of individual samples in comparison with non-selected samples. In pooled samples, however, the BoviPure-DGC improved (P < 0.05) the PSM, VCL, WOB, and IPM of chilled and frozen-thawed samples. The swim-up method improved (P < 0.05) only some kinematic variables of the individual (VCL, WOB and BCF) and cryopreserved pooled samples (VCL and ALH) in comparison with non-selected samples. In conclusion, BoviPure-DGC was more effective for recovering and selecting both fresh and cryopreserved dog epididymal sperm than the swim-up procedure improving the kinematic variables, and membranes intactness.

Transit along the vas deferens results in a high percentage of filiform spermatozoa with compacted chromatin in the rooster (Gallus domesticus).

The present work aimed to evaluate the chromatin compaction of rooster spermatozoa along the male reproductive tract, and to study the vas deferens lining cells, potentially involved in sperm maturation. Chromomycin A3 (CMA3) was used to determine the chromatin compaction of spermatozoa from testis (T), proximal (including epididymis, V1), intermediate (V2) and distal (V3) vas deferens, and ejaculate (E). Six Birchen Leonesa roosters were used. E was obtained in vivo by dorso-ventral massage. V1, V2 and V3 sperm were obtained post mortem (six pairs of vasa deferentia), by flushing. T was obtained by washing the testes, cut in halves. The fixed cells were stained with CMA3 and propidium iodide for flow cytometry assessment. Results showed higher (P P P.

Animal board invited review: Germplasm technologies for use with poultry.

Over the last century, several reproductive biotechnologies beyond the artificial incubation of eggs were developed to improve poultry breeding stocks and conserve their genetic diversity. These include artificial insemination (AI), semen storage, diploid primordial germ cell (PGC) methodologies, and gonad tissue storage and transplantation. Currently, AI is widely used for selection purposes in the poultry industry, in the breeding of turkeys and guinea fowl, and to solve fertility problems in duck interspecies crosses for the production of mule ducklings. The decline in some wild game species has also raised interest in reproductive technologies as a means of increasing the production of fertile eggs, and ultimately the number of birds that can be raised. AI requires viable sperm to be preserved in vitro for either short (fresh) or longer periods (chilling or freezing). Since spermatozoa are the most easily accessed sex cells, they are the cell type most commonly preserved by genetic resource banks. However, the cryopreservation of sperm only preserves half of the genome, and it cannot preserve the W chromosome. For avian species, the problem of preserving oocytes and zygotes may be solved via the cryopreservation and transplantation of PGCs and gonad tissue. The present review describes all these procedures and discusses how combining these different technologies allows poultry populations to be conserved and even rapidly reconstituted.

Optimization of semen cryopreservation in black-footed (Spheniscus demersus) and gentoo (Pygoscelis papua) penguins using dimethylacetamide and dimethylsulfoxide.

Black-footed penguins (Spheniscus demersus) are classified as endangered, and the populations of gentoo penguins (Pygoscelis papua) are rapidly decreasing. The optimization of semen cryopreservation in these species, for preserving their genetic diversity in genome resource banks, is essential for the success of captive breeding programs. This study compares the effectiveness of two permeating cryoprotectants, dimethylacetamide (DMA) and dimethylsulfoxide (DMSO), on frozen-thawed sperm characteristics. Semen samples were collected during each breeding season once a week during two consecutive years. Semen samples were packaged in 0.25 ml straws and frozen by placing them in nitrogen vapors. After thawing, sperm motility characteristics were examined by computer-assisted sperm analysis. Propidium iodide and SYBR-14 were used as fluorochromes for the examination of membrane integrity. DNA integrity was evaluated by TUNEL assay. Gentoo sperm characteristics after freeze-thawing did not show any differences when using DMSO or DMA. In black-footed samples, progressive motility, curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), linearity (LIN), and straightness (STR) were greater using 8% DMSO (P < 0.05) than 6% DMA. The cryoresistance ratio (CR) using 8% DMSO was greater (P < 0.05) in gentoo than black-footed samples for CR-VCL and CR-VAP, and 6% DMA returned greater CR values (P < 0.05) than in black-footed samples for all characteristics evaluated. No differences were found in DNA fragmentation. In conclusion, the present results highlight the benefits of using 8% DMSO compared to 6% DMA in penguins. Sperm from black-footed showed a higher sensitivity to freezing-thawing process than gentoo sperm.

Birchen and Blue Leonesa sperm cryopreservation: a new technique for evaluating the integrity of cockerel sperm membranes.

1. Birchen and Blue Leonesa are two endangered chicken breeds mainly raised in Curueño Valley in North Spain. The establishment of a germplasm bank to guarantee the preservation of these breeds is needed. However, cockerels from different breeder flocks can show variance in semen cryoresistance.2. The following work focused on the sperm characterisation and cryopreservation of Birchen and Blue Leonesa cockerels from four different breeders. A total of 30 semen pools were analysed. Besides conventional sperm analysis, including motility by computer-aided sperm analysis (CASA) and DNA fragmentation by TUNEL, the present study tested a double staining method (MitoTrackerTM Green FM/propidium iodide). This gave simultaneous assessment of plasma and acrosomal and mitochondrial membranes, which were previously validated by SYBR-14/PI, CASA, aniline blue and TUNEL.3. No significant differences were found among fresh semen variables between breeds and breeders. For post-thawed variables, significant differences (P < 0.05) were found between breeders in sperm viability (58.0 ± 1.90 breeder D vs. 35.2 ± 7.41 breeder A, 37.2 ± 4.09 breeder B and 22.3 ± 5.92 breeder C) and DNA fragmentation (62.4 ± 9.91 breeder C vs. 31.8 ± 7.08 breeder B and 24.5 ± 5.49 breeder D). The lowest DNA fragmentation values for semen from breeder D birds were coincident with higher integrity of the mitochondrial membrane.4. The results revealed higher sperm cryoresistance in the cockerels from one of the breeders, possibly due to differences in management system (e.g. diet, housing, control of stress elements and pathogens, reproduction practices or maintenance of genetic diversity). These differences may determine the sperm freezability, and thus the effectiveness of developing a germplasm bank.

Vitrification of Iberian wolf (Canis lupus signatus) sperm: A possible alternative to conventional cryopreservation.

Sperm vitrification is a simple, inexpensive method that allows the cryopreservation of sperm in the field and for endangered species is a useful alternative to conventional freezing. The study, therefore, is focused on the suitability of vitrification for cryopreserving Iberian wolf sperm and utilizing plasma testosterone concentration as a marker for procedure efficacy. Sperm and blood samples were collected from 17 wolves. There were 14 samples suitable for cryopreservation (12 ejaculated and two epididymal). Immediately after collection, these samples were proportioned into two aliquots for conventional freezing using a Tris-citric acid-glucose based extender (TCG) or vitrification utilizing an animal protein free extender (HTF®). Vitrification occurred by directly plunging a sperm suspension into liquid nitrogen. Sperm were assessed for motility, membrane integrity, acrosomal status and DNA integrity before and after cryopreservation. With both techniques, there were similar post-thaw/warming results (P > 0.05) with respect to progressive motility, kinetic variables VCL, VSL, VAP and BCF, DNA fragmentation, sperm membrane functionality and morphological abnormalities. Total motile sperm, progression ratios LIN, STR, and WOB, the ALH, sperm viability and sperm with intact membrane and acrosome were greater (P < 0.05) in the conventional frozen-thawed sperm than vitrified-warmed sperm. Plasma testosterone concentrations varied from 0.0 ng/mL to 7.7 ng/mL. For epididymal sperm, sperm motility and viability following thawing were greater in vitrified-warmed samples than conventionally-frozen samples; however, small sample numbers precluded statistical analysis. When considered together, these results indicate vitrification may be a possible alternative for wolf sperm cryopreservation.

Effect of glutathione on pre and post-freezing sperm quality of Indian red jungle fowl (Gallus gallus murghi).

During cryopreservation sperm encounter oxidative stress due to higher production of ROS molecules and insufficient natural antioxidant defence system. Therefore, present study was designed to identify the effects of various glutathione (GSH) concentrations on Indian red jungle fowl (Gallus gallus murghi) sperm quality and fertility pre-freezing and post-thaw incubation hours. Semen was collected from eight cocks and qualified semen ejaculates having motility >65% were pooled after initial evaluation. Semen was divided in four aliquots, diluted with red fowl extender (1:5) at 37 °C having GSH 0 mM (control), 0.1 mM, 0.5 mM and 1.0 mM, cryopreserved and stored at (-196 °C) in liquid nitrogen. Semen quality was assessed at post dilution, cooling, equilibration, and freeze-thawing at 0, 2 and 4 h of incubation at 37 °C. Sperm motility, plasma membrane integrity, viability, acrosome integrity and mitochondrial function were recorded highest (P < 0.05) with 0.5 mM GSH in extender at post-dilution, cooling, equilibration, freeze-thawing and 0, 2 and 4 h of incubation. Lipid peroxidation in sperm and seminal plasma were recorded lowest (P < 0.05) with 0.5 mM GSH during cryopreservation stages and post-thawing incubation. Moreover, antioxidant activities (total antioxidant potential and free radical scavenging capacity) were recorded highest (P < 0.05) in extender having 0.5 mM GSH. Fertility rates were recorded higher (P < 0.05) with 0.5 mM GSH compared to control. It is concluded that 0.5 mM GSH in extender improves sperm structural (sperm viability, plasma membrane integrity and acrosome integrity), functional integrity (motility, mitochondrial function) and fertility parameters of Indian red jungle fowl through enriching antioxidant potential and ameliorating the oxidative stress.

Role of changes in plasma prolactin concentrations on ram and buck sperm cryoresistance.

Seasonal endocrine changes may modify sperm cryoresistance in certain small ruminant species. The present work examines the effect of prolactin (PRL) on ram and buck sperm cryoresistance. A dopamine agonist (bromocriptine [BCR] 60 mg i.m. twice per week from May 15 to June 15, that is, approaching the summer solstice) or antagonist (sulpiride [SLP] 100 mg s.c. daily from December 15 to January 15, that is, around the winter solstice) was administered under solstice-appropriate photoperiod conditions to modify PRL secretion. Control animals received the vehicle only. Compared to the corresponding controls, BCR reduced PRL secretion to basal levels in both the rams and bucks. In rams, the cryoresistance ratios for sperm curvilinear velocity (P < 0.05) and lateral head displacement (P < 0.01) were higher for the BCR-treated animals. In bucks, neither the characteristics of fresh nor frozen-thawed sperm were affected by BCR treatment. After the administration of SLP, PRL levels increased and remained high for more than 5 h in the rams though they immediately began to fall in the bucks. By 24 h, PRL had returned to basal concentrations in both species. In rams treated with SLP, the cryoresistance ratios for sperm progressive motility, straight line velocity, sperm mean path velocity, cross beat frequency, and the progression ratios linearity, straightness and oscillation, were all lower compared to the controls (P < 0.05), while the amplitude of lateral head displacement was higher (P < 0.01). In bucks, sperm cryoresistance was not affected by SLP administration. Together, these results suggest that high levels of PRL negatively affect the cryoresistance of ram sperm, while buck sperm seems unaffected.

Effect of supplementation of valine to chicken extender on sperm cryoresistance and post-thaw fertilization capacity.

Recent reports showed a positive correlation between frozen-thawed rooster sperm DNA integrity and the concentrations of valine in seminal plasma. The present study evaluated the effect of supplementing valine to semen extender for freezing sperm of 2 endangered local Spanish chicken breeds with different sperm cryoresistance: Red Villafranquina (VF) showing low sperm DNA integrity after cryopreservation and Quail Castellana that shows higher DNA integrity. One pool of semen per breed was obtained twice a week for 10 wk (n = 40, 20 per breed). Each pool was divided into 2 fractions. One of these fractions was frozen in presence of valine as additive in the extender (concentration 10 mmol), whereas the other was used as control. The evaluation of the samples before and after freezing-thawing included motility (CASA-Mot system), viability (propidium iodide and SYBR-14), DNA integrity (terminal deoxynucleotidyl transferase dUTP nick end labeling), and fertility rate (percentage of eggs with blastoderm development after artificial insemination). Supplementation of valine increased several motility variables of fresh semen. In VF breed, valine increased percentage of progressive motile sperm (P = 0.025), curvilinear velocity (P = 0.033), straight-line velocity (P = 0.040), and average path velocity (P = 0.033), whereas progressive motile sperm (P = 0.019), curvilinear velocity (P = 0.006), straight-line velocity (P = 0.003) and average path velocity (P = 0.004) were improved in the Quail Castellana breed. Valine addition increased the DNA integrity of cryopreserved semen (decreased post-thaw DNA fragmentation) in both breeds, with a significant effect (P = 0.002) in VF (36.3% VF-control vs 31%VF-valine). As expected, Quail Castellana cryopreserved sperm control showed higher fertility rate (34.4% ± 12.1) than VF cryopreserved sperm control (16.1% + 6.2). Supplementing valine to the freezing extender doubled (P = 0.026) the fertility rate of VF (32.6% ± 12.2) compared with the control (16.1% + 6.2). In conclusion, supplementation of valine to chicken freezing extenders shows a positive effect on DNA fragmentation and fertilizing ability of frozen-thawed sperm, with a better response in a breed considered as the lowest freezer in our conservatory.

Influence of testosterone administration at the end of the breeding season on sperm cryoresistance in rams (Ovis aries) and bucks (Capra hircus).

This study examines the influence of administering testosterone at the end of the mating season, on the responses (morphometric and functional) of ram and buck sperm to freezing-thawing. Five rams were administered 25 mg testosterone propionate (TP) subcutaneously in 2 mL of olive oil twice per week (Monday and Thursday) from October 1 to 31; 5 bucks received exactly the same treatment but from November 1 to 30. Control groups were administered 2 mL of olive oil without TP twice per week over the same period. In the rams, no significant differences were seen in plasma testosterone between the treated and control groups during treatment (0.8 ± 0.2 ng/mL vs 1.5 ± 0.5 ng/mL; P > 0.05). Significant differences were seen in this respect, however, in the bucks (4.3 ± 0.8 ng/mL and 6.9 ± 0.9 ng/mL; P < 0.05). In the rams, TP treatment increased (P < 0.05) the straight-line velocity (VSL), linearity (LIN), straightness (STR) and wobble (WOB) values in fresh sperm samples. Similarly, in the frozen-thawed samples, TP treatment increased the VSL, average path velocity (VAP), LIN and WOB values (P < 0.05) compared with controls. In the bucks, treatment with TP had no effect on any measured variable in fresh sperm; frozen-thawed sperm, however, returned greater VSL, LIN, STR, and WOB values (P < 0.05) than did controls. In the rams, treatment with TP led to a reduction in all fresh sperm head morphometric variables (P < 0.05). Freezing-thawing further reduced (P < 0.05) all morphometric variables in both the control and treated groups. In the bucks, treatment with TP increased (P < 0.05) the length, area, and perimeter of fresh sperm cells, unlike that seen in ram sperm. Compared with fresh sperm, freezing-thawing led to reduced (P < 0.05) morphometric variables in both the control and treated bucks, except for the sperm head width, which in the controls remained unchanged. In conclusion, TP treatment at the end of the mating season affected fresh sperm quality, in both Spanish Merino rams and Murciano-Granadina bucks, in a species-specific manner, but improved the sperm kinetic variables after freezing-thawing in both species, apparently improving sperm cryoresistance. Treatment with TP affects the dimensions of the sperm head in a species-specific manner.

Cryopreservation effects on canine sperm morphometric variables and ultrastructure: Comparison between vitrification and conventional freezing.

Semen cryopreservation is an increasingly demanded technique in canids, particularly in order to preserve and spread high genetic value material. Sperm vitrification may represent an interesting alternative to costly and time consuming conventional freezing. The objective of this study was to evaluate the effect of sperm vitrification on sperm morphometry and ultrastructure compared to conventional freezing. Pools of nine beagle dogs were both frozen and vitrified. Computerized morphological parameters (length, wide, area and perimeter) and sperm ultrastructure, using scanning and transmission microscopy, were analysed in both fresh and in thawed/warmed samples. There were no differences (p > 0.05) between post-thaw and fresh morphometric variables of the sperm heads. However, cluster analysis revealed that sperm-heads turned out to be smaller after thawing (p < 0.05) in two of the four subpopulations. Vitrification-warming process led to an overall increase in sperm-head size. Furthermore, the sperm head size increased after warming in two subpopulations (p < 0.05). In conclusion, the variations in the sperm head area depended on the cryopreservation procedure (conventional freezing or vitrification). Conventional freezing tended to decrease the head dimensions, at least in some subpopulations, and vitrification led to an overall increase in the sperm head size. Decondensation of chromatin and plasma membrane blebbing in the head region was observed by transmission electron microscopy in several vitrified sperm, which might explain the increase of head dimensions detected by CASA-Morph system.

In vitro supplementation of testosterone or prolactin affects spermatozoa freezability in small ruminants.

In small ruminants, testosterone and prolactin plasma concentrations show circannual fluctuations as an adaptation mechanism to their seasonal breeding behavior. Sperm resistance to the freezing-thawing process shows seasonal fluctuation throughout the year, with lower sperm freezability at the beginning of the breeding season when prolactin and testosterone levels reach their maximum concentration. Nevertheless, whether these hormones directly affect post-thaw sperm quality parameters is still unclear. The objective was to study the effect of testosterone or prolactin added in vitro on sperm freezability in domestic ram (Ovis aries) and buck (Capra hircus). Sperm samples were incubated for 1 h with a range of testosterone (0, 2, 4, or 6 ng/mL; Exp. 1) or prolactin (0, 20, 100, 200, or 400 ng/mL; Exp. 2) concentrations. Samples were cryopreserved by slow freezing in straws at 0 h and after 1 h incubation. Sperm viability, acrosome integrity, motility, and kinetic parameters were assessed at 0 and 1 h in fresh and frozen-thawed samples. Results showed no hormone effect in fresh sperm, whereas these hormones affected post-thaw sperm parameters. In Exp. 1, in vitro incubation with testosterone decreased the post-thaw acrosome integrity of ram sperm (from 68.1 ± 6.3% to 49.6 ± 3.9%; P < 0.05). In Exp. 2, in vitro incubation with prolactin decreased the post-thaw acrosome integrity of ram (from 78.2 ± 3.4% to 66.3 ± 3.5%; P < 0.05) and buck sperm (from 81.7 ± 2.5% to 67.6 ± 3.5%; P < 0.05). Moreover, prolactin increased the post-thaw amplitude of lateral head displacement in ram sperm (from 3.3 ± 0.1 µm to 3.8 ± 0.2 µm; P < 0.05). In conclusion, either testosterone or prolactin added in vitro decreased the post-thaw acrosome integrity of ram and buck sperm. This suggests a destabilization process that could be decreasing sperm freezability when physiological levels of these hormones are high in vivo.

Chronic use of a GnRH agonist (deslorelin) or immunization against GnRH: effects on testicular function and sperm quality of bucks.

Chronic use of GnRH agonists and immunization against GnRH have been used as reversible contraceptive methods. The aim of this study was to compare the effectiveness of both treatments to inhibit reproductive function of adult bucks, in terms of strength and duration of the effects. We used 9 control untreated bucks (CON), 7 bucks treated chronically with a GnRH agonist (subcutaneous implants with 7.4 mg of deslorelin, Suprelorin, Virbac) (AGO), and another 7 bucks were immunized against GnRH (dose of 2 mL of Improvac-Zoetis with 300 µg of a synthetic incomplete analog of natural GnRH; 300 mg of diethylaminoethyl-dextran; and 2.0 mg of chlorocresol) (IMM). Testicular and sperm evaluations, testosterone concentrations, and male odor were determined from 4 wk before applying the treatments until 17 mo of their application. Scrotal circumference of CON (21.0 ± 0.1 cm) and IMM (21.2 ± 0.2 cm) was greater than that of AGO bucks (19.9 ± 0.2 cm) (P < 0.05 for each), without difference between CON and IMM bucks. Pixels' color intensity of testicular ultrasound images was not affected by treatment (general mean ± SEM: 116.0 ± 1.8). Testosterone concentration was greater in CON than AGO and IMM in months 3 and 4, greater in CON and IMM than AGO bucks in months 15 and 16, and greater in IMM than CON and AGO bucks in month 17 (P < 0.05 for all comparisons). Male odor was greater in CON (1.5 ± 0.0) than IMM bucks (1.3 ± 0.0) and greater in IMM than AGO (1.1 ± 0.0) bucks (P < 0.05 for each). Treatment negatively affected all the sperm variables: the total number of sperm in the ejaculate, sperm motility, sperm with normal morphology and sperm with integral membrane function. It was concluded that both treatments were effective in inhibiting the reproductive axis; however, neither of them produced azoospermia or decreased testosterone concentrations to undetectable levels. With both treatments, there were individual males exhibiting characteristics of fertility in all periods of the study. However, chronic use of a GnRH agonist seemed to be the most effective treatment in terms of duration and strength.

Continuous presence of females in estrus does not prevent seasonal inhibition of LH and androgen concentrations in bucks.

In male goats, being in permanent visual contact with females in estrus does not prevent seasonal variation in certain endocrine hormone levels and sexual activities. In this study, we tested whether continuous and full contact with females in estrus prevented seasonal endocrinological variation in bucks. In 1 experiment (Exp. 1), we verified that the sudden introduction of goats in estrus increased the plasma concentrations of androgen in bucks during the nonbreeding season under our experimental conditions. In another experiment (Exp. 2), we tested the ability of estrous goats to prevent seasonal inhibition of LH and androgen secretions in bucks kept in permanent and full contact with them. In Exp. 1, 3 groups of bucks (n = 5 in each group) were isolated from females from the months of July to January. On January 27, one group continued being isolated from females; a second group was exposed to ovariectomized, untreated goats; and a third group was exposed to ovariectomized goats with induced estrus. Plasma androgen concentrations were determined every 2 h from 8 h before to 8 h after the introduction of females. The introduction of estrus-induced goats significantly increased androgen concentrations, which were higher than in the isolated bucks, as well as in those exposed to untreated goats (P < 0.05). In Exp. 2 (n = 5 per group), one group of bucks was isolated from females from October to July, whereas two other groups remained in contact with ovariectomized goats, either untreated or regularly induced to estrus. In the three groups of bucks, plasma concentrations of LH were determined once during the months of October, February, March, and June, whereas androgen concentrations were determined weekly from October to July. The mean plasma LH and androgen concentrations were low and did not differ among the groups of bucks during the normal seasonal period of sexual inactivity (P > 0.05). We conclude that full contact and sexual interactions with estrus-induced goats failed to stop the seasonality of LH and androgen plasma concentrations of bucks, although bucks could respond to the introduction of females by acute increases in plasma LH and androgen.