Effect of column filtration upon the quality parameters of fresh dog semen

Practical applications of sperm selection techniques as a tool for improving reproductive efficiency

Modern biotechnologies are used extensively in the animal breeding industry today. Therefore, it is essential that sperm handling procedures do not modulate the normal physiological mechanisms occurring in the female reproductive tract. In this paper, the different selection mechanisms occurring in vivo are described briefly, together with their relevance to artificial insemination, followed by a detailed description of the different selection processes used in reproductive biotechnologies. These selection methods included fractionated semen collection, cryopreservation, biomimetic sperm selection, selection based on hyaluronic acid binding, and last, but not least, sperm sex selection. Biomimetic sperm selection for AI or for cryopreservation could improve pregnancy rates and help to reverse the decline in fertility seen in several domestic species over the recent decades. Similarly, selection for hyaluronic acid binding sites may enable the most mature spermatozoa to be selected for IVF or ICSI.

Freezability of equine semen after glass beads column separation

REASONS FOR PERFORMING STUDY

The success rate of artificial insemination following the freezing of stallion semen is limited; therefore, improving the stallion semen quality after the freezing and thawing process is a necessary objective.

OBJECTIVES

To investigate the influence of glass bead column separation on the freezability of stallion semen.

HYPOTHESIS

Glass beads in a column separator remove damaged and dead spermatozoa in the ejaculate during centrifugation.

METHODS

In total, 50 ejaculates from 6 Lipizzaner stallions were studied. Each ejaculate was divided into 2 parts, one half processed following standard procedure and the second half used for the column separation procedure. After freezing, semen quality was evaluated using standard tests for motility, morphology and viability of semen.

RESULTS

Motility and progressive motility of the column-separated (CS) semen were significantly higher (P < 0.001) before freezing and immediately, 24 and 48 h after thawing. A significant increase (P < 0.001) in the percentage of hypoosmotic positive spermatozoa was observed in CS samples. The percentage of total morphological changes in the separated samples before and after freezing was significantly lower (P < 0.001) compared with samples prepared using the standard procedure. A substantial decrease (P < 0.001) was found in the percentage of spermatozoa with damaged acrosomes. However, the percentage of spermatozoa with coiled tails was increased in the separated samples (P < 0.001).

CONCLUSIONS

Column separation before freezing has a positive effect on the quality of thawed equine semen.

POTENTIAL RELEVANCE

The quality of CS frozen/thawed samples indicates their potential use for increasing insemination success in mares.

Effects of filtration through Sephadex columns improve overall quality parameters and "in vivo" fertility of subfertile refrigerated boar-semen

This study was performed to test the effects of filtration through several chromatographic resins on the semen quality parameters (percentages of viability, altered acrosomes and morphological abnormalities, motion characteristics and the response to the Osmotic Resistance Test) of boar ejaculates of poor quality. Our results indicate that filtration through a non-ionic Sephadex resin bed (Sephadex G-15), combined with a glasswool subjection bed, induced an overall improvement of semen quality parameters, especially seen in a significant (P<0.05) decrease in the percentages of morphological abnormalities and an increase of several motility parameters related to velocity and linearity. Similar results, although less intense, were observed when the filtration through G-15 resin was accompanied by an ionically neutral polypropylene disk bed instead of glasswool. On the other hand, filtration through two separate ion-exchange Sephadex resins, cationic C-50 and anionic A-50, have less beneficial, and even detrimental, effects on boar-semen quality. In all cases, filtration was accompanied by a significant (P<0.01) decrease in the final concentration of the samples. Ultrastructural and lectin studies showed that the interaction between sperm and chromatographic resins depends on the resin type utilized, and in the case of G-15 it seems that it works by trapping that sperm with not enough strength to overcome the physical resistance associated with chromatographic particles. When semen of poor quality was filtered through G-15 resin and then was utilized for "in vivo" fertility trials, a significant (P<0.05) increase in the percentage of fertility was observed, when compared with the same, but unfiltered, samples. In summary, our results strongly indicate that filtration through ionically inert, Sephadex chromatographic resins could be a very useful and practical method to improve both boar-semen quality and fertilizing ability, especially from mediocre and/or subfertile samples.

Effects of filtration of semen doses from subfertile boars through neuter Sephadex columns

This study was designed to develop a method of improving the quality of sperm obtained from subfertile Piétrain boars. Seminal doses were filtered through neuter Sephadex columns (G-25 Medium, G-50 Fine, G-50 Medium and G-75, length 10 +/- 0.5 cm, flow rate 1 ml/20 s). Doses were prepared by pooling 10 ml semen samples collected from 58 asthenoteratospermic boars and diluted the sperm-cell rich fraction 1 : 6 in Betsville thawing solution extender. Sperm quality was determined before and after the filtering process. Sperm morphology and motility were assessed using the computer program SCA 2002 production, and sperm vitality was evaluated by fluorescence multistaining. ORT and HRT tests were used to determine the osmotic resistance of spermatozoa, and metabolic performance was assessed by measuring l-lactate production. Results indicate that the filtration process rendered increased proportions of mature spermatozoa and of viable spermatozoa with an intact acrosome, nucleus and mitochondrial sheath. Sperm filtration led to decreased percentages of spermatozoa with proximal and distal droplets and of agglutinated spermatozoa, along with slightly diminished ORT values. HRT scores and L-lactate production were unaffected. Our findings indicate that filtering through a Sephadex column improves the sperm morphology and vitality of seminal doses obtained from subfertile boars, but produces no functional changes in the spermatozoa. All four column types yielded similar results.

Use of a new computer-assisted sperm analyzer for the assessment of motility and viability of dog spermatozoa and evaluation of four different semen extenders for predilution

The aims of this study were to evaluate a new computer-assisted sperm analyzer (CASA; SpermVision, Minitüb, G) for the analysis of canine spermatozoa, and to suggest suitable semen diluents that should influence motility and viability parameters to the lowest extent. For these purposes, the sperm-rich fractions from 40 ejaculates were diluted with either saline (S), PBS, autologous prostate secretion (third fraction, PROST) or a modified TRIS buffer (TRIS; [Pena, A., Johannisson, A., Linde-Forsberg, C., 1999. Post-thaw evaluation of dog spermatozoa using new triple fluorescent staining and flow cytometry. Theriogenology 52, 965-980]). Viability was investigated both objectively with SYBR-14/PI in SpermVision and subjectively with carboxyfluoresceindiacetate (CFDA) fluorescence stains by optical microscopy. For all diluents and for most parameters, the intra- and inter-assay coefficients of variation were below 10% and 20%. Effects after dilution with TRIS and PROST were similar, but only after dilution with TRIS, total motility significantly correlated with estimated motility in raw semen (P<0.01, R=+0.514). After dilution, estimated and measured motility values were positively related, but correlated significantly with PBS only (P<0.01). After dilution with PBS and S, all motility parameters were significantly lower in comparison with PROST and TRIS, and after dilution with PBS, significantly more membrane damages occurred than with TRIS, S and PROST (P<0.05, <0.05 and <0.01). In samples diluted with TRIS, membrane integrity of spermatozoa determined with SYBR-14/PI and CFDA staining correlated significantly (R=+0.686; P<0.01). Concerning the location of membrane damages, no differences appeared after dilution with different media. In conclusion, SpermVision proved to be an accurate analyzer for the objective assessment of both motility and viability of canine spermatozoa. TRIS and PROST were the media with the lowest influences on parameters of canine semen, and are therefore recommendable for the use in SpermVision.

The value of canine semen evaluation for practitioners

Compared to human medicine, little is known in canine medicine regarding specific findings on semen evaluation and their correlation with fertility. Suggestions to optimize quality of semen evaluation in veterinary practice include creating standardized protocols for evaluation of all semen parameters and updating those protocols as needed; creating some form of quality control for the clinic laboratory; educating owners about our inability to predict with 100% accuracy whether dogs with poor semen quality never could impregnate a bitch or whether dogs with excellent semen quality always could impregnate a bitch; and generating protocols for further diagnostic work-up for those dogs with abnormal semen quality.

Glucose- and fructose-induced dog-sperm glycogen synthesis shows specific changes in the location of the sperm glycogen deposition

Immunocytochemistry of glycogen deposition in dog sperm from fresh ejaculates showed that 53.7% of the population had glycogen at the midpiece, whereas 27.3% of the whole population accumulated glycogen only in the post-acrosomal region of the head. A similar distribution was observed when glycogen synthase, the enzyme which controls glycogen deposition, was studied. Incubation of spermatozoa with fructose increases the intracellular glycogen levels in a time- and concentration-dependent manner. Moreover, after incubation with 2 mM fructose for 30 min, 47.3% of the spermatozoa had glycogen located in both the midpiece and post-acrosomal zone, 25.4% of the population showed the polysaccharide only in the midpiece, and 24.7% of the spermatozoa showed a uniform distribution of glycogen all over the cell. Similar results were observed after incubation with 10-mM fructose. The distribution of glycogen synthase followed a similar pattern to that of glycogen. Incubation with glucose also induced a time- and concentration-dependent increase of glycogen content, whereas incubation with 2 mM glucose for 30 min showed that the majority of the population (81.2%) had the glycogen distributed throughout either the midpiece or the midpiece and the post-acrosomal zones together. There were practically no cells with a uniform glycogen distribution. Similar results were obtained after incubation with 10-mM glucose, whereas glycogen synthase suffered a similar glucose-induced distribution change. These results indicate that dog-sperm glycogen metabolism is modulated by changes in the activity of their controlling enzymes and also by changes in the specific location places where glycogen synthesis is produced.