Computer-assisted sperm analysis of fresh epididymal cat spermatozoa and the impact of cool storage (4°C) on sperm quality

Cushioned and high-speed centrifugation improve sperm recovery rate but affect the quality of fresh and cryopreserved feline spermatozoa

The development of endoscopic transcervical catheterization (ETC) in the queen increases the interest in handling fresh and cryopreserved feline semen. The ETC requires a small volume of the insemination dose with a high concentration, not easily reached with the actual frozen technique in this species. Centrifugation is widely used to concentrate spermatozoa for several purposes, but this process is detrimental to spermatozoa. This study verified the effects of conventional and cushioned centrifugation on fresh and cryopreserved feline spermatozoa. To this, semen was collected from 20 toms, grouped in seven pools and diluted. After dilution, the pools were divided into two aliquots, the first used for centrifugation on fresh semen, and the second, after freezing, on cryopreserved semen. Centrifugation regimens were: conventional at 500×g, conventional at 1000×g, and cushioned (iodixanol) at 1000×g. The sperm recovery rate was calculated for the three centrifugation regimens, and sperm kinematics, membrane and acrosome integrity, and plasma membrane stability on viable spermatozoa were assessed as endpoints. The data reported in this study showed that the centrifugation at 500×g resulted in negligible effects on both fresh and cryopreserved spermatozoa, but the lower recovery rate (62.4 ± 3.1 % and 60.2 ± 1.6 %, respectively) underlines the loss of a large proportion of spermatozoa, unfavourable in a species with small total sperm ejaculated. On the other hand, the centrifugation at 1000×g improved the recovery rate (86.9 ± 4.3 % and 89.8 ± 2.4 % in fresh and cryopreserved samples, respectively), but was more deleterious for feline spermatozoa, especially in cryopreserved samples (i.e. total motility of 40.7 ± 5.4 % compared with 57.2 ± 9.8 % in cryopreserved uncentrifuged samples, P < 0.05), resulting in artificial insemination doses of lower quality. The recovery rate in cushioned centrifugation appeared less efficient, likely due to the small volume of feline samples, which makes difficult the separation of sperm pellet and cushioned fluid. Interestingly, in cryopreserved samples centrifuged at 1000×g the number of viable spermatozoa with membrane destabilization (31.3 ± 3.2 %) was greater than uncentrifuged (4.1 ± 0.7 %, P < 0.05) and those centrifuged at 500×g (9.8 ± 1.3 %, P < 0.05), suggesting modifications induced by the cryopreservation amplifies centrifugation sublethal damage on feline spermatozoa. Cushioned centrifugation on cryopreserved samples showed kinematics similar to uncentrifuged samples, but higher viable spermatozoa with membrane destabilization (37.4 ± 3.4 % vs 4.1 ± 0.7 %; P < 0.05). In felines, g-force is crucial for sperm recovery rate during centrifugation, with better results at 1000×g; on the other hand, greater g-forces could have a significant impact on the quality of feline insemination dose, especially in cryopreserved samples.

Collection of epididymal semen in the tomcat (Felix catus) by stereomicroscope-aided retrograde flushing (SARF) improves sample quality

In small and laboratory animals epididymal spermatozoa can be collected only by the mincing technique however, blood and cell debris contamination may adversely affect the quality of the samples. This study aimed at performing the retrograde flushing technique, for the first time, in the tomcat. In the first experiment attempts to insert a blunted needle into tomcats' ductus deferentes were made and the cannulation time and the success rate were recorded. In the second experiment, insertion of the needle into the ductus was carried out under a stereomicroscope for one testis, while the other was submitted to mincing for sperm recovery and the samples obtained from paired testes were compared. In the first study, only twenty-eight percent of the cannulation attempts were successful whereas in the second experiment, 91% of the deferentes were successfully cannulated: 80% of the ducts were cannulated in less than three minutes. The stereomicroscope-aided retrograde flushing samples showed significantly higher sperm viability, motility and velocities, as compared to those resulted from mincing. The domestic cat serves as a model for more than 36 species of wild felids; the developed stereomicroscope-aided retrograde flushing technique has the potential to become the gold standard method for harvesting spermatozoa of endangered species that have a small ductus deferens.

Effect of season on the dynamics of cat sperm DNA fragmentation

BACKGROUND

Feline species undergo reproductive seasonality; thus, sperm characteristics, such as DNA integrity, can be affected by the photoperiod. This study was conducted to determine the effect of seasonal changes on sperm quality and on the dynamics of sperm DNA fragmentation. Epididymal spermatozoa were collected from 36 tomcats subjected to bilateral orchiectomy during breeding (BS) and non-breeding (NBS) seasons. Sperm samples were obtained by cutting the cauda epididymis and assessed for sperm motility, concentration, acrosome integrity, plasma membrane integrity and sperm morphology. Sperm DNA fragmentation was evaluated by the sperm chromatin dispersion test after 0, 6, and 24 h of incubation at 37 °C.

RESULTS

The total sperm motility and plasma membrane integrity values were greater during the BS, while the percentages of abnormal sperm and head defects were lesser (p < 0.05). No significant differences in DNA fragmentation were found between seasons after sperm collection. DNA damage was greater after 24 h of incubation at 37 °C in both seasons, although the percentage of spermatozoa with fragmented DNA was significantly lesser in the BS than in the NBS at 24 h (p < 0.05).

CONCLUSIONS

The study suggests seasonal changes in some of the quality parameters of cat sperm. DNA fragmentation dynamics were affected by the time of incubation and reproductive season; therefore, this technique might be used as an additional tool to test the potential fertility of semen samples used in feline-assisted reproduction.

The influence of Percoll® density gradient centrifugation before cryopreservation on the quality of frozen wisent (Bison bonasus) epididymal spermatozoa

Background

The wisent (Bison bonasus) is a species that has undergone a population bottleneck. Homozygosity is prevalent within the population and may have a negative impact on semen quality in wisent bulls. Semen samples containing a large amount of functionally and morphologically impaired or dead spermatozoa have lower tolerance for cryopreservation process. Such samples are prone to involve damage acrosomes, to produce and release reactive oxygen which negatively affects proper function of spermatozoas. It is a good practice to select intact and viable gametes before subjecting the sample to cryopreservation to improve the efficiency of this process. The aim of this study was to assess the ability of Percoll® density gradient centrifugation in order to improve the quality of wisent spermatozoa after cryopreservation. Spermatozoa samples were analysed with computer-assisted semen analysis system and flow cytometry.

Results

Percoll® density gradient centrifugation resulted in increased percentage of motile spermatozoa, higher proportion of spermatozoa with normal morphology and proper functionality but also in a significant reduction of the total number of gametes. Nevertheless, the concentration of frozen spermatoza was still sufficient for obtaining a few complete insemination doses suggested for cattle from each epididymis.

Conclusions

While creating a high-quality genetic reserve, for in vitro fertilisation purposes, eliminating detritus and improving the overall quality of samples is more important than total number of spermatozoa. For these reasons, the achievement of higher post thaw quality of spermatozoa justifies the purification of samples by centrifugation in a Percoll® density gradient prior to the cryopreservation process.

A triple stain method in conjunction with an in-depth screening of cryopreservation effects on post-thaw sperm in dogs

In order to accurately analyze the possible side effects of sperm cryopreservation, an in-depth screening of post-thaw sperm status is necessary. Thus, this study aimed to identify thorough effects of sperm cryopreservation, by evaluating the integrity of all specific structures of the canine spermatozoa. Thirteen (n = 13) mature dogs of different breeds were selected. Six dogs (n = 6) were subjected to sperm cryopreservation, whereas seven dogs (n = 7) were used as semen donors to validate a simultaneous assessment of sperm plasmatic, acrosomal, and mitochondrial membranes (triple stain) by fluorescent probes. Fresh and post-thaw semen samples were evaluated through a computer-assisted analysis of sperm motility, sperm morpho-functional evaluation, triple stain and sperm DNA integrity. Post-thaw semen samples had lower total and progressive motility, as well as higher percentage of minor and major defects. Moreover, post-thaw samples had higher percentage of sperm with plasma membrane and mitochondrial damage but intact acrosome, and also sperm with simultaneous damaged plasma, acrosomal and mitochondrial membranes. Furthermore, post-thaw sperm had higher protamination deficiency and DNA fragmentation. In conclusion, cryopreservation has a broad impact in sperm morphology and function, altering motility patterns, plasma, acrosome and mitochondrial membranes integrity, as well as sperm DNA.

Spermatogenic Activity and Sperm Traits in Post-Pubertal and Adult Tomcats (Felis catus): Implication of Intra-Male Variation in Sperm Size

Tomcats are considered to be adults at 1 year of age, although many reach sexual maturity at an earlier age. Nevertheless, we still know little about whether the spermatogenic activity and sperm quality of mature under one-year-old tomcats differ from those of tomcats that are over one-year-old. This study aims to evaluate the spermatogenic activity, sperm traits, and their relationships in mature tomcats at two different ages. Sixteen tomcats showing complete spermatogenesis and spermatozoa in their epididymal caudae were used and classified according to their age as post-pubertal (<1 year old) or adult (˃1 year old). Our results show that adult cats have higher epididymal sperm concentration and lower coefficient of variation in sperm head width and ellipticity than post-pubertal cats. However, they do not differ in their testicular and epididymal mass, spermatogenesis, and sperm traits such as motility, mitochondrial activity, morphology, morphometry, as well as plasma membrane, acrosome, and DNA integrity. Reduced intra-male variation of sperm head ellipticity is associated with higher testis mass, epididymis mass, and sperm concentration. Interestingly, low intra-male variation in sperm head size is associated with increased Sertoli cell function and reduced post-meiotic germ cell loss. These findings increase our knowledge about feline reproductive physiology and provide new insights into the functional significance of low intra-male variation in sperm size and shape in tomcats.

Can amides be alternative cryoprotectors for the preservation of feline semen?

Sperm cryopreservation is a tool for the conservation of the genetic material of animals of genetic importance or for species preservation. In the case of domestic cats, this can be used to generate information about seminal harvest, evaluation and preservation, which is especially important due to its applicability to wild felids. This study evaluated seminal samples harvested by urethral catheterisation from 13 adult domestic cats. Samples were cryopreserved with experimental groups of extenders were defined by the penetrating cryoprotectant: 6% glycerol (GLY6%), 3% dimethylacetamide (DMA3%) and 3% dimethylformamide (DMF3%). The samples were thawed and evaluated by conventional microscopy and by computer-assisted sperm analysis (CASA). The structural and functional membrane integrity was assessed by supravital tests (EOS), hypoosmotic swelling tests (HOST) and flow cytometry (FC). There was a correlation (P < 0.05) between total motility and EOS (r = 0.54), HOST and FC (r = -0.62) and total motility and flow cytometry (r = 0.63), indicating that these are complementary parameters that increase the accuracy of the feline sperm quality evaluation post-thaw. The results regarding the structural and functional integrity of the sperm plasma membrane did not differ (P > 0.05) among groups. However, the DMA3% group had a lower (P < 0.05) percentage of morphological changes in the sperm tail compared to samples cryopreserved with GLY6% and DMF3%. Additionally, DMA3% provided lower values of immobile sperm post-thaw when compared to DMF3%. DMA is an interesting alternative to GLY and superior to DMF for the cryopreservation of feline semen at the studied concentrations.

Recovery and cryopreservation of epididymal sperm from domestic cat using powdered coconut water (ACP-117c) and TRIS extenders

Cryopreservation of cats epididymal spermatozoa allows the conservation of the genetic material and the study of the cryogenic effect applied to the gametes of other felines. However, this biotechnique still presents variable results, being necessary the investigation of alternative extenders. Powdered coconut water (ACP-117c) has been efficient in the sperm freezing of several species and in the cat sperm refrigeration. Therefore, we aimed to evaluate the effect of the freezing stages and the quality of the cats' epididymal spermatozoa after thawing, using ACP-117c. Epididymides (n = 36) from 18 cats were processed using TRIS (n = 18) or ACP-117c (n = 18) for sperm recovery. The sperm were immediately evaluated. Then, this was cooled, glycerolized, frozen and thawed, and re-evaluated at each stage for sperm kinetics by Computer Assisted Semen Analysis, viability, functionality (HOST), mitochondrial activity (DAB) and morphology. There was a reduction in total motility and progressive motility after thawing in both groups, and TRIS was superior to ACP-117c. The curvilinear velocity reduced after thawing with ACP-117c. Viability decreased after glycerolization in TRIS. Although it also reduced after thawing in both groups, it was higher in TRIS. There was no change on HOST. Mitochondrial activity decreased during the cryopreservation steps for both extenders. Nevertheless, TRIS presented a higher percentage of spermatozoa from DAB class I and II after thawing. Morphology did not differ between extenders. Therefore, ACP-117c is an alternative for the recovery of cat epididymal spermatozoa; however, it is not efficient for freezing. Glycerolization and thawing are the most critical stages, regardless of the extender.

Morphological and morphometric characterization of domestic cat epididymal sperm

Sperm morphometry is the tool that confers objectivity to the morphological evaluation by accurately measuring the dimensions of the gamete and its structures. Thus, the aim of the study was to perform a morphometric characterization of the domestic cat sperm. Therefore, sperm samples were collected from twenty pairs of epididymis in a TRIS extender at 37ºC. An aliquot of the sample was used to make a smear with Rose Bengal solution, and afterwards, the morphology and morphometry were analysed. In the morphology, were quantified the percentage of normal sperm cells, morphological changes of head, midpiece and tail. In morphometry, each normal sperm cell was measured for length, width, area and perimeter of head and midpiece, tail length and total length. The parameters ellipticity, elongation, regularity and rugosity were also determined. The percentage of normal sperm was 67.21%. Of the abnormalities, the curled/folded tail, followed by the curved midpiece, abnormal shaped head and detached head were the most quantified. The sperm head presented 5.56 ± 0.01 μm and 3.10 ± 0.01 μm of length and width, respectively. The head area was 16.94 ± 0.05 μm² , while the perimeter was 16.16 ± 0.03 μm. In the derived parameters, the values were as follows: ellipticity of 1.81 ± 0.00; elongation of 21.39 ± 0.12; regularity of 0.81 ± 0.00; and rugosity of 0.14 ± 0.00. The midpiece presented length and width of 7.96 ± 0.01 μm and 0.76 ± 0.01 μm, respectively. The mean length of the sperm tail was 45.12 ± 0.06 μm, and the total cell size was 58.67 ± 0.06 μm. Thus, it was concluded that the cat sperm is an elongated cell, with high rugosity and regularity. The spermatic tail represents more than ¾ of the total length of the cell and the midpiece exceeds the length of the head.

Positive effect of butylated hydroxytoluene (BHT) on the quality of cryopreserved cat spermatozoa

The semen cryopreservation processes are associated with state of oxidative stress induced by high levels of reactive oxygen species (ROS), causing damage to functional spermatozoa. Whereby, antioxidants have been utilized to scavenge or neutralize the elevated levels of ROS. The aim of at the present study was to evaluate the effect of adding BHT to the freezing extenders on post-thaw characteristics of domestic cat spermatozoa. Semen samples were frozen in Tris-fructose-citric acid-based extender, supplemented with different concentrations of BHT (0.5 mM, 1.0 mM and 2.0 mM) and a control sample without antioxidant. After thawing, sperm samples were assessed for motility by computer-assisted sperm analysis and viability, acrosome integrity, superoxide anion production and membrane lipid peroxidation status by flow cytometry. In the study, the parameters of sperm motility and acrosome integrity were significantly higher in 2.0 mM BHT compared to sperm frozen in the extender with other concentrations and control (P < 0.05), in addition, this concentration reduced significantly the superoxide anion production and lipid peroxidation of the sperm. The results demonstrated that the supplementation of BHT to the freezing extender could protect the function and cellular structure of domestic cat sperm from cryoinjuries.

Changes in sperm function and structure after freezing in domestic cat spermatozoa

Sperm cryopreservation allows for a long-term storage of genetic. However, changes due to factors as cold shock, osmotic and oxidative stress cause reduction in viability and fertilising ability of frozen/thawed spermatozoa. Therefore, evaluation of cryoinjury of cat spermatozoa is a key factor in achieving better cryopreservation results. This study analysed the changes in structural and functional after freezing in ejaculated domestic cats spermatozoa. Semen samples (n = 60) were analysed before and after freezing, progressive motility was determined with computer-assisted sperm analysis and viability, and acrosome intact spermatozoa, mitochondrial function and superoxide anion ( O 2 - ) were assessed by flow cytometry. The results demonstrated that cryopreservation induced changes in all sperm parameters (p < 0.05). Total sperm motility, viability, acrosome integrity and mitochondrial function of fresh samples were near to 80% and decrease near to 40% in frozen/thawed spermatozoa (p < 0.05); nevertheless, in contrast to all other sperm parameters, the sperm positive with O 2 - increased post/thawing (p < 0.05). In conclusion, changes in frozen/thawed spermatozoa could be related to the effect of oxidative stress due to the increase in the synthesis of O 2 - and a concomitant loss of functional competence. Therefore, the evaluation of these sperm parameters could contribute to complement the analysis of fresh or frozen semen used ART.

Characterization and cryopreservation of Amur leopard cats (Prionailurus bengalensis euptilurus) semen collected by urethral catheterization

The Amur leopard cat (Prionailurus bengalensis euptilurus) is a globally endangered species, and there is thus an urgent need to increase its population. The objectives of this study were to: (1) confirm the utility of urethral catheterization (UC) for semen collection from Amur leopard cats; (2) investigate proper dilution media for fresh semen; and (3) investigate the effectiveness of sperm cryopreservation, including examining the effect of glycerol concentration. Six adult males in captivity (mean weight 5.03 ± 0.44 kg, aged 2-6 years) were included. All study procedures were performed during the breeding season (February to April) over two consecutive years. Semen samples (n = 28) were collected four or five times from each animal (four times for two animals and five times for four animals) by UC under general anaesthesia, and their characteristics (including sperm motility) were evaluated. First, the sperm motility in semen diluted in Ham's F-10 or phosphate buffer saline (PBS) was compared. Next, semen diluted with TEST-yolk buffer containing 2%, 4%, or 6% glycerol was frozen in a liquid nitrogen tank, and sperm motility and acrosome integrity were evaluated after thawing. No difference in motility was observed between sperm diluted in Ham's F-10 and PBS. The percentages of sperm motility and kinetic values in semen frozen in 2% or 4% glycerol were higher than those in semen stored in 6% glycerol. In conclusion, the UC method for semen collection is recommendable for Amur leopard cats and should be useful for artificial insemination. Although sperm motility decreased after thawing, samples thus preserved may be usable for advanced reproductive techniques, such as intracytoplasmic sperm injection or in-vitro fertilization.

Characteristics of urethral and epididymal semen collected from domestic cats--A retrospective study of 214 cases

This study was designed to describe and compare basic semen characteristics and sperm motility parameters obtained via computer-assisted sperm analysis (CASA) in feline semen collected from the urethra and epididymis, on the basis of large, unselected population of domestic cats. The semen collected from 214 males was subjected for routine semen assessment and CASA evaluation. Semen collected by urethral catheterization (CT) and by epididymal slicing (EP) has comparable characteristics according to total sperm count (47.7 ± 42.1 and 52.9 ± 45.0), subjective motility (71.1 ± 17.0 and 69.3 ± 13.9), viability (74.9 ± 13.4 and 76.7 ± 10.6), and morphology (52.6 ± 19.0 and 47.2 ± 17.4). The study of a large feline population confirmed a high incidence of teratospermy in cats, which negatively affects sperm motility parameters assessed by CASA. A lack of a correlation between CT and EP semen for total sperm count and viability, as well as occasional gross differences between the morphology of CT and EP semen of the same cat suggests that many factors may affect sperm cells, and the fertility and/or infertility of patients should not be assessed after examining only one sample. Additionally, technical problems with assessment of EP samples (understated results) suggest that CT semen is more appropriate for an analysis by CASA than EP.

Effects of various physical stress factors on mitochondrial function and reactive oxygen species in rat spermatozoa

The aim of the present study was to evaluate the effects of various physical interventions on the function of epididymal rat spermatozoa and determine whether there are correlations among these functional parameters. Epididymal rat spermatozoa were subjected to various mechanical (pipetting, centrifugation and Percoll gradient separation) and anisotonic conditions, and sperm motility, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) were evaluated. Repeated pipetting caused a loss in motility, PMI and MMP (P<0.05). Minimal centrifugation force (200 g) had no effect on motility, PMI and MMP, whereas an increase in the centrifugation force to 400 g or 600 g decreased sperm function (P<0.005). Percoll gradient separation increased total motility, PMI and MMP (P<0.05). However, the spermatozoa that were subjected to mechanical interventions showed high susceptibility to a ROS stimulant (P<0.005). Anisotonic conditions decreased motility, PMI and MMP, and hypotonic conditions in particular increased basal ROS (P<0.05). In correlation tests, there were strong positive correlations among total motility, PMI and MMP, whereas ROS showed no or negatively weak correlations with the other parameters. In conclusion, the physical interventions may act as important variables, affecting functional parameters of epididymal rat spermatozoa. Therefore, careful consideration and proper protocols for handling of rat spermatozoa and osmotic conditions are required to achieve reliable results and minimise damage.

Computer-assisted sperm analysis in dogs and cats: an update after 20 years

In dogs and cats, computer-assisted sperm analysis (CASA) was originally described almost 20 years ago. Subsequently, numerous CASA systems were validated and used for various applications in dogs and to a lesser extent in cats. CASA systems offer an accurate, rapid, objective and simultaneous assessment of different semen parameters allowing the visualization of subtle changes in sperm characteristics, which cannot be identified by conventional semen analysis. The main problems of these computerized measuring devices are the relatively high investment costs and the need for standardization and validation before any practical use is possible. In comparison with automated motility and concentration assessment, automated morphometry and morphology assessment is more complex and time-consuming. Once validated, CASA systems can be routinely used in veterinary centres for assessment of fertility and for the improvement of sperm diluters, cooling and cryopreservation procedures in dogs and cats. Furthermore, information obtained by CASA systems could also be important when monitoring for example the effect of environmental stress on spermatozoa and for toxicity studies. In cats, CASA is less documented, and most studies describe the characteristics of epididymal sperm, which is frequently used for in vitro fertilization in cats. Implementation of the CASA technique in cat reproduction could be interesting to further optimize assisted reproductive techniques in domestic cats and endangered wild felids.

Cryoprotective effect of different glycerol concentrations on domestic cat spermatozoa

Cryopreservation of spermatozoa is a pivotal tool in assisted reproduction, and studies aiming to establish optimal freezing/thawing protocols are essential to enhance sperm survival. The objectives of the present study were to (1) compare the cryoprotective efficiency of three different glycerol concentrations (3%, 5%, and 7%) on the basis of post-thaw sperm quality and (2) investigate whether the incidence of morphologically abnormal sperm in fresh samples is related to cryodamage sensitivity. Semen was collected from six tomcats using an artificial vagina (total 18 ejaculates). Each ejaculate was diluted using Tris-egg yolk-based extender (TEY), evaluated, equally divided into three aliquots, and rediluted using TEY with and without glycerol to achieve final concentrations of 3%, 5%, and 7%. Samples were loaded into 0.25 mL straws, equilibrated for 60 minutes at 5 °C, frozen, and then thawed at 46 °C for 12 seconds. Fresh and frozen-thawed samples were evaluated for sperm motion parameters (computer-assisted sperm analysis), plasma membrane integrity (PMI; propidium iodide and carboxyfluorescein diacetate), and DNA integrity (acridine orange). Plasma and acrosomal membrane integrity were assessed by flow cytometry (propidium iodide and fluorescein isothiocyanate-conjugated pea (Pisum sativum) agglutinin) immediately after thawing. Sperm motion parameters were also evaluated at 30 and 60 minutes of postincubation. For all treatment groups, cryopreservation significantly impaired the PMI and sperm motion parameters, except for straightness and amplitude of lateral head displacement. DNA integrity showed a slight reduction (P < 0.05) when 3% glycerol was used. The percentage of total motility, progressive motility, and rapid spermatozoa were significantly lower immediately after thawing and up to 60 minutes of incubation for the 3% glycerol group when compared with 5% and 7%. No difference (P > 0.05) was found for PMI, acrosome integrity, and DNA integrity among post-thaw groups. However, higher (P < 0.05) incidence of viable cells with reacted acrosome and dead cells with intact acrosome were observed with 7% and 3% glycerol, respectively. Percentage of morphologically abnormal spermatozoa in fresh sample was positively correlated with PMI only in the 3% glycerol group and negatively correlated with sperm motility in the 5% and 7% groups. In conclusion, the final concentration of 5% glycerol offered better cryoprotective effect for ejaculated cat sperm, and the relationship found between prefreezing sperm morphology and post-thaw sperm quality showed to be dependent on final glycerol concentration.

Boar seminal plasma components and their relation with semen quality

Select boar seminal plasma (SP) components and their relation to semen quality were investigated. Thirty nine boars from three artificial insemination (AI) centers were divided into group A (GA: > 80% normal sperm and >70% motility) and group B (GB: < 80% normal sperm and < 70% motility). Each ejaculate was collected and semen volume, concentration, sperm motility (computer aided semen analysis; CASA), morphology, and vitality (both eosin nigrosin staining) were investigated. The SP was separated and analyzed for aspartate-amino-transferase (AST), γ-glutamyl-transferase (GGT), alkaline phosphatase (ALP) activity, and the concentrations of sodium (Na), potassium (K), chloride (Cl), calcium (Ca), phosphate (PO(4)(3-)), magnesium (Mg), selenium (Se) and zinc (Zn) were assessed. Repeated measures (2 months interval) were conducted in eight boars of GA from one AI center. The activity of GGT (r = -0.482) and ALP (r = -0.459) was moderately associated (p < 0.05) with ejaculate volume and strongly associated with concentration (r = 0.580 and r = 0.618, respectively; p = 0.000). Moderate associations (p < 0.05) were found between ALP (r = 0.439), GGT (r = 0.387), Na (r = -0.428), K (r = 0.354), and Se (r = 0.354) with progressive motility. The SP concentration of Na (r = -0.401), Cl (r = -0.521), and K (r = 0.350) was associated (p < 0.05) with normal morphology. Only Mg was associated (p < 0.05) with membrane damage (r = -0.335). The concentration of Na, Cl, and Zn (1681.0 vs. 1701.0 µg/dL) was different between groups (p < 0.05). Repeated measures showed significant differences in time but only for Na, Mg, and Zn (p < 0.05). In conclusion, several biochemical components of SP were related to semen quality. The analysis of biochemical parameters could provide extra information about reproductive health of AI boars.

Effect of dilution temperature on boar semen quality

As boar semen is very sensitive to cold shock and changes in temperature during semen processing can have a profound impact on semen quality, the effect of the extender temperature at the time of dilution was investigated in a two-step dilution protocol for boar semen being processed for liquid storage. Fifteen boars of different breeds and ages from a commercial artificial insemination centre were included. One ejaculate per boar was collected and processed with Beltsville Thawing Solution semen extender. Each ejaculate was diluted (1 : 1) at 30 °C, and subsequently, the samples were diluted (30 × 10(6) sperm/ml) with either preheated extender [29.3 °C ± 0.2 °C, group A (GA)] or extender at room temperature [22.7 °C ± 0.6 °C, group B (GB)]. Samples were transported to the Faculty of Veterinary Medicine (University of Ghent, Belgium) in two isotherm boxes (one per group), stored at 17 °C and investigated for three consecutive days (D0 to D2). At D0, D1 and D2, motility parameters [computer-assisted semen analysis (CASA)] and the per cent of sperm with intact membrane (% IM) by eosin nigrosin staining were evaluated. At D0 and D2, the % of sperm with intact acrosome (% IA) was studied by Pisum sativum agglutinin staining. The average temperature of the 1 : 1 dilution was 29.4 °C ± 1.1 °C immediately after extender addition. No significant differences were found between groups for per cent motility [79.3 ± 9.0 for GA and 81.1 ± 9.2 for GB (p = 0.372)], % progressive motility [56.5 ± 13.3 for GA and 58.4 ± 13.8 for GB (p = 0.737)] or any CASA parameter. No differences were found for % IM [85.1 ± 10.7 and 84.5 ± 3.8 for GA and GB, respectively (p = 0.761)] and % IA [72.2 ± 9.4 for GA and 68.3 ± 16.6 for GB (p = 0.792)]. In conclusion, when a two-step dilution is performed, preheating the extender for the second dilution to match the semen temperature did not result in better semen quality compared to a dilution at a moderate room temperature.