RESUMO
Modern livestock breeding is basically dependent on the proper use of semen for artificial insemination (AU) of femeles and of other reproductive biotechnologies such as the production of embryos in vitro for embryo transfer (IVP). Both these techniques have made possible not only the wide dissemmation of genetic material onto breeding populations but also anhanced the selection of best sires, owing to the development of better diagnostic techniques for sperm function and of preservation of seminal material over time. Although use ofliquid semen cooled to room temperature, to intermediate temperatures (+16-20ºC) or chilled (+5ºC) dominates in different species cryopreservation is preferred in bovine A1 and it is advancing in other species by the design of new containers, freezing methods and the use of better insemination strategies. Techniques to separate the aliquot of most robust spermatozoa from an ejaculate have shown a renascent particularly for sires with low sperm quality, and technological advances in separating spermatozoa for c hromosomal sex make the technique suitable for commercial use, following applicat ion of novel findings in sperm and seminal plasma (SP) diagnostics and function. Alongside, knowledge of the epigenome and signalling c apabilities of the semen (sperm and SP) call s for further studies regarding transgene production via ICSI for IVP or AI.(AU)
Assuntos
Animais , Criação de Animais Domésticos , Análise do Sêmen/métodos , Espermatozoides/citologia , Biotecnologia/tendênciasRESUMO
This review summarizes those methods - established and emerging of semen assessment whose outcom e intents revealing its potential fertility and, as a carry over concept, that of the sire whose semen we examined. The review does not, however, focus on the wide display of current techn iques designed to explore specific or multiple sets of sperm attributes essential for fertilization but on two basic con cerns present: the heterogeneity of the sperm suspension and the multitude of attributes required for each spermatozoon to be fertile; concepts that shadow our diagnostic capabilities. The review points out advancements in the exploration of the genome, the transcriptome, and the proteome of both spermatozoa and the seminal plasma which unveil how spermatozoa modulate their own survival an d signal to the environment when displaying degenerative changes. Specific seminal plasma components, both among individuals and portions of the ejaculate, not only relate to survival but also signal differential immune tolerance by the female with a previ ously unattended linkage to fertility. Lastly it foresees how Cytomics, combining novel designed motility analyzers, flow cytometers and enhanced digital imaging shall dominate the landscape of andrological laboratories and enable quick determinations on huge sperm numbers for markers highly relevant to sperm function and hence, for fertility.(AU)
Assuntos
Animais , Análise do Sêmen/veterinária , Estro/genética , Espermatozoides/citologia , Bovinos/fisiologiaRESUMO
This review summarizes those methods - established and emerging of semen assessment whose outcom e intents revealing its potential fertility and, as a carry over concept, that of the sire whose semen we examined. The review does not, however, focus on the wide display of current techn iques designed to explore specific or multiple sets of sperm attributes essential for fertilization but on two basic con cerns present: the heterogeneity of the sperm suspension and the multitude of attributes required for each spermatozoon to be fertile; concepts that shadow our diagnostic capabilities. The review points out advancements in the exploration of the genome, the transcriptome, and the proteome of both spermatozoa and the seminal plasma which unveil how spermatozoa modulate their own survival an d signal to the environment when displaying degenerative changes. Specific seminal plasma components, both among individuals and portions of the ejaculate, not only relate to survival but also signal differential immune tolerance by the female with a previ ously unattended linkage to fertility. Lastly it foresees how Cytomics, combining novel designed motility analyzers, flow cytometers and enhanced digital imaging shall dominate the landscape of andrological laboratories and enable quick determinations on huge sperm numbers for markers highly relevant to sperm function and hence, for fertility.
Assuntos
Animais , Análise do Sêmen/veterinária , Espermatozoides/citologia , Estro/genética , Bovinos/fisiologiaRESUMO
Modern livestock breeding is basically dependent on the proper use of semen for artificial insemination of femeles and of other reproductive biotechnologies such as the production of embryos in vitro for embryo transfer (IVP). Both these techniques have made possible not only the wide dissemmation of genetic material onto breeding populations but also anhanced the selection of best sires, owing to the development of better diagnostic techniques for sperm function and of preservation of seminal material over time. Although use ofliquid semen cooled to room temperature, to intermediate temperatures (+16-20ºC) or chilled (+5ºC) dominates in different species cryopreservation is preferred in bovine A1 and it is advancing in other species by the design of new containers, freezing methods and the use of better insemination strategies. Techniques to separate the aliquot of most robust spermatozoa from an ejaculate have shown a renascent particularly for sires with low sperm quality, and technological advances in separating spermatozoa for c hromosomal sex make the technique suitable for commercial use, following applicat ion of novel findings in sperm and seminal plasma (SP) diagnostics and function. Alongside, knowledge of the epigenome and signalling c apabilities of the semen (sperm and SP) call s for further studies regarding transgene production via ICSI for IVP or AI.
Assuntos
Animais , Análise do Sêmen/métodos , Criação de Animais Domésticos , Espermatozoides/citologia , Biotecnologia/tendênciasRESUMO
Visual motility analysis is the basis for routine quality evaluation of stallion semen, although its prognostic value for fertilizing ability is considered low. The present study evaluated the ability of a novel computer-assisted motility analyzer (QualiSperm) to determine the motility and velocity of ejaculated, extended stallion spermatozoa (collected from 10 stallions, 3 ejaculates/stallion) and following two different colloidal centrifugation methods (one- or two- layer), compared to visual evaluation by two independet operators. The Qualisperm instrument was able to retrieve and analyze ~10 times more spermatozoa per sample compared to routine visual estimation on the same time frame (~1,100 vs ~100 spermatozoa).The proportion of motile spermatozoa increased after the colloid-separation, compared to the extended ejaculates (P < 0.05) in some stallions. However, owing to the large variation seen among ejaculates and stallions, both for extended ejaculate (P < 0.05) as well as for the colloid centrifugations (P < 0.01), the differences were lost when the entire population was examined statistically. Interestingly, significant differences were seen for individual stallions between the measurements ofQualisperm and observers, as well as between observers (P < 0.05). Apart from the significantly higher number of spermatozoa analyzed at one time, the Qualisperm system provided a parameter that could simply not be estimated by visual assessment; mean sperm velocity (in µm/sec). Sperm velocity, upon which every computer assisted instrumentation base their evaluations, varied among stallions (and ejaculates within stallions, P < 0.05), with a tendency to increase after colloid-separation, thus suggesting the Qualisperm system might be able to differentiate sperm sub-populations. Due to its higher accuracy (in terms of sperm numbers examined) and speed, the Qualisperm system appears to be a suitable instrument for routine evaluation of equine semen.(AU)
Assuntos
Animais , Espermatozoides/citologia , Motilidade dos Espermatozoides , Sêmen , Cavalos/classificaçãoRESUMO
Visual motility analysis is the basis for routine quality evaluation of stallion semen, although its prognostic value for fertilizing ability is considered low. The present study evaluated the ability of a novel computer-assisted motility analyzer (QualiSperm) to determine the motility and velocity of ejaculated, extended stallion spermatozoa (collected from 10 stallions, 3 ejaculates/stallion) and following two different colloidal centrifugation methods (one- or two- layer), compared to visual evaluation by two independet operators. The Qualisperm instrument was able to retrieve and analyze ~10 times more spermatozoa per sample compared to routine visual estimation on the same time frame (~1,100 vs ~100 spermatozoa).The proportion of motile spermatozoa increased after the colloid-separation, compared to the extended ejaculates (P < 0.05) in some stallions. However, owing to the large variation seen among ejaculates and stallions, both for extended ejaculate (P < 0.05) as well as for the colloid centrifugations (P < 0.01), the differences were lost when the entire population was examined statistically. Interestingly, significant differences were seen for individual stallions between the measurements ofQualisperm and observers, as well as between observers (P < 0.05). Apart from the significantly higher number of spermatozoa analyzed at one time, the Qualisperm system provided a parameter that could simply not be estimated by visual assessment; mean sperm velocity (in µm/sec). Sperm velocity, upon which every computer assisted instrumentation base their evaluations, varied among stallions (and ejaculates within stallions, P < 0.05), with a tendency to increase after colloid-separation, thus suggesting the Qualisperm system might be able to differentiate sperm sub-populations. Due to its higher accuracy (in terms of sperm numbers examined) and speed, the Qualisperm system appears to be a suitable instrument for routine evaluation of equine semen.
Assuntos
Animais , Espermatozoides/citologia , Motilidade dos Espermatozoides , Sêmen , Cavalos/classificaçãoRESUMO
Difficulties to be overcome in the widespread use of artificial insemination (AI) in mares are low sperm survival and poor sperm quality, which are encountered frequently among breeding stallions. Therefore, a method is needed to prolong the useable life of stallion spermatozoa destined for AI. In a preliminary study using 8 ejaculates from one stallion, density gradient centrifugation or centrifugation through a single layer of silica colloid appeared to prolong sperm motility compared to uncentrifuged spermatozoa, thereby potentially extending the useable life of treated stallion spermatozoa for AI. Furthermore, there was an improvement in sperm morphology, with the number of morphologically normal spermatozoa increasing from 42 to 60.5% and with the removal of approximately 60% spermatozoa with head or tail defects from the original population. No difference between the two centrifugation methods, in terms of yield or duration of spontaneous motility, could be detected in this study. Either of these methods of colloidal centrifugation could be a useful aid to preparing stallion spermatozoa for artificial breeding techniques, including AI.(AU)
Assuntos
Animais , Bovinos , Coloides , Espermatozoides/citologia , Cavalos/classificação , Centrifugação/instrumentaçãoRESUMO
Difficulties to be overcome in the widespread use of artificial insemination (AI) in mares are low sperm survival and poor sperm quality, which are encountered frequently among breeding stallions. Therefore, a method is needed to prolong the useable life of stallion spermatozoa destined for AI. In a preliminary study using 8 ejaculates from one stallion, density gradient centrifugation or centrifugation through a single layer of silica colloid appeared to prolong sperm motility compared to uncentrifuged spermatozoa, thereby potentially extending the useable life of treated stallion spermatozoa for AI. Furthermore, there was an improvement in sperm morphology, with the number of morphologically normal spermatozoa increasing from 42 to 60.5% and with the removal of approximately 60% spermatozoa with head or tail defects from the original population. No difference between the two centrifugation methods, in terms of yield or duration of spontaneous motility, could be detected in this study. Either of these methods of colloidal centrifugation could be a useful aid to preparing stallion spermatozoa for artificial breeding techniques, including AI.
Assuntos
Animais , Bovinos , Coloides , Espermatozoides/citologia , Cavalos/classificação , Centrifugação/instrumentaçãoRESUMO
In vitro sperm migration in cervical mucus relates to sperm concentration at the utero-tubal junction and to in vivo fertilization performance in goats. The present study aimed to characterize, using Computer-Assisted Sperm Analysis (CASA), motility patterns depicted by buck sperm and their relation to the migration efficiency in homologous (goat) and heterologous (heifer) cervical mucus in vitro. Semen was collected from 23 sexually mature bucks from three breeds by artificial vagina and sperm were assessed for motility parameters with a Hobson Sperm analyzer following extension in Sperm Analysis Medium (SAM). To study the relationship between kinematics parameters and the ability of sperm to migrate in cervical mucus, in a first experiment, motility performance of buck sperm suspended in SAM was compared against seminal plasma. In a second experiment, kinematics parameters of sperm were characterized. In a third experiment, bucks with sperm that differed in specific motion parameters were compared for the ability of their sperm to migrate through goat and bovine cervical mucus collected at estrus. In a fourth experiment, ejaculates that were compared in their migration ability and were assessed simultaneously for their motility parameters. Overall, sperm suspended in SAM medium had better velocity and similar linearity and lateral head displacement than those suspended in seminal plasma; furthermore, caprine sperm swam relatively fast (relative to bovine and ovine sperm), following a very linear trajectory. Under the conditions used, velocity parameters, linearity and lateral head displacement seemed to be related to sperm migration efficiency in homologous mucus but not in bovine cervical mucus.
Assuntos
Muco do Colo Uterino/fisiologia , Cabras/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Motilidade dos Espermatozoides/fisiologia , Animais , Cruzamento , Bovinos , Feminino , Masculino , Especificidade da EspécieRESUMO
The current use of ingredients of animal origin, such as egg yolk, in semen extenders presents a risk of microbial contamination, and has led to the search for alternatives. Such an extender is commercially available for bull semen (Bioexcell), IMV, L'Aigle, France), and it has previously been tested in vitro for freezing ram semen, with satisfactory results. The aim of the present study was to compare the fertility results of ewes in Uruguay, after cervical insemination with ram semen that was frozen in Bioexcell versus semen frozen in a conventional milk-egg yolk extender (control). Semen from five Corriedale rams was frozen, using a split sample design, in either milk-egg yolk or Bioexcell extender, using a two-step extension method. The sperm parameters assessed after thawing were subjective motility, membrane integrity (SYBR-14/PI), and capacitation status (CTC). Thawed semen was inseminated intracervically once during spontaneous estrus in 970 Corriedale ewes that grazed in natural pastures, under extensive management conditions. Fertility was recorded as nonreturn rates at 21 days (NRR-21) and 36 days (NRR-36) after artificial insemination (AI), as well as pregnancy rate (PR-US, diagnosed ultrasonographically 50 days after AI of the last ewe). Subjective motility was slightly higher in Bioexcell than in the milk extender (47 vs. 46.5%; NS), as was membrane integrity (38 vs. 37.7%; NS) and the percentage of uncapacitated spermatozoa (28.5 vs. 26.3%; NS). There were no statistically significant differences in fertility rates found between Bioexcell and the control extender: NRR-21 (35.9 vs. 33.2%), NRR-36 (34.8 vs. 32.6%), and PR-US (28.4 vs. 27.2%). In conclusion, Bioexcell appears to be an alternative to the conventional milk-egg yolk extender for freezing ram semen, and provides similar fertility results after cervical AI under extensive management conditions. Thus, Bioexcell, containing no additives of animal origin, can offer a safer alternative when frozen semen is used for introducing new genetic material into a flock or a country.