Effect of semen extenders on sperm parameters of ram semen during liquid storage at 4°C

Effect of Three Commercially Available Extenders Containing Phospholipids of Different Sources on Skopelos Buck Liquid-Stored Sperm Quality

The effect of four extenders on buck semen quality parameters was examined during a 48 h liquid storage. Semen was collected from six Skopelos bucks and diluted in the following extenders, containing: soy lecithin (SL, OviXcell®), plant phospholipids (PP, AndroMed®), egg yolk lecithin (EY, Steridyl®), or no phospholipids (basic extender). Samples were stored at 5 °C for 48 h and assessed at 0, 24 and 48 h for viability (eosin-nigrosin), acrosome integrity (SpermBlue®), membrane functional integrity (HOST), mitochondrial function (Rhodamine 123/SYBR-14/PI) and motility parameters (CASA). No significant reduction in total or progressive spermatozoa motility and mitochondrial function was observed at 24 h, whereas they all dropped significantly at 48 h, in all extenders. Spermatozoa viability, cell membrane functionality and acrosome integrity dropped progressively (0 h > 24 h > 48 h) in all groups. No significant difference among extenders was observed concerning spermatozoa mitochondrial function. Overall, spermatozoa viability, cell membrane functionality and acrosome integrity were higher in the three commercial extenders, compared to the basic extender. SL and EY extenders (OviXcell® and Steridyl®, respectively) preserved viability more effectively than the PP extender (AndroMed®). Total motility was higher in the PP extender, compared to the SL extender. Spermatozoa acrosome integrity tended to be higher in the EY extender compared to all the other extenders. Further investigation of the protective potential of different types of cryoprotectants on liquid buck semen storage is important.

Effects of different extenders, storage temperatures, and antioxidant supplementation on chilled semen quality: a review

The successful preservation of ram semen is essential to promote genetic variability, ensure semen transportation, and inseminate multiple ewes. Currently, either animal or plant-based lipoprotein-based extenders are used for semen preservation. Animal product-based extenders include milk and egg yolk, while soybean lecithin is a plant-based extender. Although extenders containing products of animal origin better preserve the quality of chilled semen, the in vivo efficacy after 24 h of storage is still of great concern. Storage temperature is another important and effective factor in preserving sperm quality, whereby different storage temperatures are adopted to enhance the storage life of sperm. Low temperatures (4-5 °C) better preserve sperm quality for a longer duration than high temperatures (15, 20, and 25 °C). Moreover, antioxidant supplementation has a positive impact on sperm quality during liquid storage. The current review summarizes the outcomes of various extenders, different storage temperatures, and antioxidant supplementation on the liquid storage of ram sperm.

Effect of modified CEP-3 diluents with aqueous soybean extract on liquid semen quality in Ongole crossbred bull

Background and Aim

Egg yolk (EY) is commonly used as an extracellular cryoprotectant in semen diluents but has some negative effects. Therefore, this study aimed to assess the potential of lecithin derived from plants, such as soybeans, as an alternative extracellular cryoprotectant and to characterize liquid semen quality of Ongole crossbred bulls using a modified caudal epididymis plasma-3 [CEP-3 (m)] as a base diluent and aqueous soybean extract (ASE).

Materials and Methods

A bull with progressive motility (PM) of fresh semen >70% was used. Two soybean extracts were also used, namely, ASE 1 and ASE 2, obtained by extraction procedures 1 and 2, respectively. The study was conducted using an experimental design with 11 treatments and ten replications, with diluents comprising different levels of ASE 1 and ASE 2, as well as a positive control with 10% EY. The parameters measured were motility (M) and its kinetic parameters, including PM, M, velocity curve linear, velocity straight linear, velocity average pathway, linearity, straightness, wobble, amplitude lateral head beat cross frequency, and hyperactivity using computer-assisted sperm analysis, viability, and spermatozoa abnormalities.

Results

The CEP-3(m) diluent formula and ASE 1 at a 30% level maintained the PM of spermatozoa up to day 5 (40.7% ± 16.1%) of cold storage. Meanwhile, the CEP-3(m) diluent formula and ASE 2 could only maintain PM >40% until day 3 (42.1% ± 13.5%) of cold storage at a 30% level. The CEP-3(m) diluent and ASE 1 at a level of 25%-30% supported spermatozoa life (viability) up to day 5 with a value >80% (81.8 ± 3.5; 86.4 ± 2.6). The abnormality value of spermatozoa in various diluents during cold storage on days 0-5 was below 20%.

Conclusion

Soybean extracts 1 and 2 can substitute EYs as extracellular cryoprotectants in modified CEP-3 basic diluents. Soybean extract 1 can support the life of spermatozoa up to day 5 but may cause the viscosity and movement of spermatozoa to be hyperactive. Soybean extract 2 can support the life of spermatozoa up to the 3rd day of cold storage and produces progressive (non-rotating) movement patterns. Further, research is recommended with higher levels of ASE 2.

Effects of extender type and storage time on sperm quality parameters of Kail ram semen stored at 5 °C

The study was designed to evaluate the effect of different extenders and storage times on sperm quality parameters of extended Kail ram semen. Semen was collected from five adult Kail rams using an artificial vagina. Semen samples with >70% total sperm motility were pooled, diluted with Tris (TR), sodium citrate (SC), and skim milk (SM)-based extenders, and stored at 5 °C. Sperm motility and kinematics, viability, and plasma and acrosomal membrane integrity were assessed every 24 hrs for 120 hrs. Sperm longevity was estimated by placing semen in a water bath at 37°C to assess sperm kinematics. Storage time as the main effect had a negative (P < 0.05) impact on sperm quality parameters. The percentages of total motile (TM), progressive motile (PM), rapid, and medium progressive (MP) motile sperm were similar at 24 hrs of storage for the three extenders. However, semen extended in TR had a higher (P < 0.05) percentage of TM, PM, rapid, and MP sperm compared to SM and SC extenders at 48 hrs of storage. The sperm kinematics (VCL, VSL, VAP, and ALH) of progressive sperm were similar for all three extenders up to 72 hrs of storage. In addition, semen extended in TR had a higher (P < 0.05) percentage of sperm with intact plasma and acrosomal membranes at a storage time of 48 hrs. At 37 °C, the percentage of TM and PM sperm was higher (P < 0.05) in the TR extender than in the SM and SC extenders at 60 minutes and beyond. In conclusion, the Kail ram sperm extended in TR and stored at 5 °C maintained better quality after 48 hrs storage than sperm extended in SM and SC extenders. At 37 °C, sperm extended in TR also retained better quality parameters at 60 min and afterward than sperm extended in SM and SC.

The Effect of Different Extenders on the Quality Characteristics of European Red Deer Epididymal Sperm Stored at 5 °C

The aim of this study was to evaluate the effect of different extenders on the quality of European red deer epididymal sperm stored at 5 °C. Epididymal spermatozoa were collected post mortem from 10 stags and diluted with three extenders (Bovidyl®, BoviFree®, and BioXcell®) and stored at 5 °C. Sperm motility (TMOT), motility parameters (system CASA), plasma membrane integrity (SYBR-14+/PI−), acrosomal membrane integrity (FITC-PNA−/PI−), mitochondrial activity (JC-1/PI), viability, and apoptotic-like changes (YOPRO/PI) were evaluated. The analyses were conducted on the first and successive days of storage (D1−D7). The applied extender, storage time, and the interactions between these factors significantly (p < 0.001) affected most of the analyzed parameters whose values were highest in sperm samples stored in Bovidyl®, regardless of storage time. In Bovidyl®, BoviFree®, and BioXcell® extenders, TMOT values were estimated at 83%, 63%, and 59%, respectively, on D3. The extenders significantly influenced DNA integrity on D7. The percentage of dead sperm increased from D3. The quality of stored sperm cells was significantly influenced by the extenders’ biochemical composition. BoviFree® and BioXcell® contain glycerol which could contribute to deteriorating the quality of spermatozoa stored at 5 °C. Sperm cells stored in the egg yolk-based extender (Bovidyl®) were characterized by the highest viability and functionality.

Ultrastructural Modification of Ram Sperm Frozen with Cyclohexanediol and Trehalose

In this study, the effects of trehalose and 1, 3-cyclohexanediol (1, 3-CHD) on the ultrastructure of frozen-thawed ram sperm were assessed and compared. In the control group, sperm were frozen without trehalose and 1, 3-CHD. In the trehalose group, 100 mM trehalose was used for sperm cryopreservation. In the cyclohexanediol group, the freezing extender contained 100 mM 1, 3-CHD. The transmission electron microscope (TEM) was used to observe the ultrastructural alterations of sperm. For verification of the TEM results, the plasma membrane and acrosome integrity of ram frozen sperm was assessed. Three fertility-proven rams were used in this study. Semen collection was repeated 6 times. The collected semen was pooled to preclude the individual difference each time. The sperm collected from a representative ram were used for ultrastructural observation. The TEM results indicated extensive and severe cryoinjuries on the main organelles of ram frozen sperm. Some alterations in plasma membrane, including detachment, rupture, dilation, or loss, appeared in post-thaw sperm. The bending shape and leakage of genetic materials were also observed in the nucleus. In addition, the outer acrosome membrane in some frozen sperm was broken or partly lost. Further, leakage of the inner contents of acrosomes also occurred. Sperm mitochondria was negatively influenced by cryopreservation. With 1, 3-CHD or trehalose, the percentage of sperm with normal acrosomes was 62% or 64%, and it was significantly higher than that of the control (41.51%, p < 0.05). However, different from trehalose, 1, 3-CHD cannot efficiently protect the post-thaw integrity of the plasma membrane (48.09% vs. 26.92%, p < 0.05). The TEM results were consistent with the quality assessment of frozen-thawed sperm. Collectively, trehalose and 1, 3-CHD can mitigate cryoinjuries on sperm ultrastructure. The cryoprotective effects of trehalose on sperm plasma membrane are superior to 1, 3-CHD. Sperm plasma membrane is the most sensitive to cryoinjuries, followed by acrosomes, mitochondria, and nuclei.

Cooled storage of semen from livestock animals (Part II): Camelids, goats, and sheep

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques in cooled storage of semen from livestock animals such as camelids, goats, and sheep. Facing worldwide environmental changes and a trend towards more conscious and healthy eating behaviors, the development of a stable animal breeding industry is a significant challenge for the near future. In the present review, factors influencing semen handling in camelids, goats and sheep are described and relevant methods as well as current trends to improve liquid-storage of cooled semen are discussed, including extenders, additives, cooling rates, and storage temperatures. The species-specific physiology and resulting challenges are taken into consideration. While the main problem for camelid semen processing is the relatively greater viscosity as compared with that of some other animals, the deciding factor for successful artificial insemination (AI) in goats and sheep is the site (i.e., cervical or vaginal) of semen placement in the reproductive tract. Due to the type of cervical anatomy, the penetration of the cervix when using AI instruments is rather difficult. Furthermore, the seminal plasma of small ruminants affects the interaction with milk-based extenders and egg yolk which results in species-specific regimens for cooled liquid-preservation. Comparing all three species, the greatest pregnancy rates were obtained by AI with goat semen after cooled liquid-storage for several days.

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

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

Mechanisms of ROS-induced mitochondria-dependent apoptosis underlying liquid storage of goat spermatozoa

Liquid storage of spermatozoa is important for artificial insemination and herd genetic breeding. However, the extended time of storage inducing the rapid decline in spermatozoa quality limits the development of this technology. The molecular mechanisms underlying liquid storage of spermatozoa remain largely unexplored. In this study, the effects of liquid storage on functional quality of spermatozoa were assessed in goat (Capra hircus). The time-dependent decline in spermatozoa motility showed a strong correlation with the significant increase in apoptosis. Moreover, apoptosis-related ultrastructural changes were observed, especially the defects in mitochondria. A significant decrease in mitochondrial membrane potential and changes in the expression of mitochondrial apoptosis-related proteins indicated mitochondrial dysfunction and mitochondrial apoptotic pathway activation. Notably, the abnormally high level of reactive oxygen species (ROS) caused by liquid storage resulted in oxidative damage to mitochondria and accelerated mitochondria-dependent apoptosis, as demonstrated by the addition of ROS scavenger N-acetylcysteine. Furthermore, critical differentially expressed proteins involved in mitochondria-dependent apoptosis and antioxidant defense were identified and profiled by quantitative proteomic analysis, facilitating the understanding of molecular regulation of ROS-induced mitochondria-dependent apoptosis. These outcomes provide insights into the mechanisms underlying liquid storage of goat spermatozoa and enhance the progress of semen storage technology.

Effect of resveratrol supplementation to Triladyl® on the quality of ram chilled semen

The present investigation aimed to estimate the in vitro effects of resveratrol (RES) on the quality of chilled ram semen. Resveratrol was added to Triladyl® in three different concentration as 0 (control), 200 or 400 μM. Semen was collected from three Najdi rams, pooled and extended with one of three previous extenders for a final concentration of 600×106 sperm/ml. Then, the diluted semen was cooled gradually, and stored at 4°C. The total motility, viability, plasma membrane integrity and acrosome integrity were assessed at 0, 24, 72 and 120 h of storage. The thermal incubation test was evaluated at day 7. The survival time, total motility and the progressive motility were registered at day 15 of storage. After 4 h of incubation, the percentage of live sperm was significantly lower in the control group than in other groups. Results of survival time, total motility and progressive motility at day 15 of liquid storage were significantly higher in RES groups than that of the control. Based on the results of incubation resistance, survival time, total and progressive motility, it could be concluded that adding 200 and 400 μM of RES to Triladyl extender can improve the quality of ram semen during chilled storage at 4°C.

Effect of three commercial extenders on sperm motility and fertility in liquid ram semen stored at 15 °C or 5 °C

The effect of different extenders on sperm motility and fertility was evaluated during liquid storage of ram semen at 5 °C and 15 °C. The semen was collected, pooled and diluted in three commercial extenders: Inra 96® (INRA) based on skimmed milk, Biladyl® A fraction (BIL) based on egg yolk, and Ovixcell® (OVIX) based on soybean lecithin. Then, sperm motility was evaluated at 0, 6, 24, 48, 72 and 96 h. In order to evaluate fertility, samples stored at 15 °C were used after dilution in INRA and OVIX. Results showed that progressive motility was significantly higher up to 72 h of storage in sperm samples maintained at 5 °C in comparison with 15 °C, similarly for each tested diluent. When samples were stored at 5 °C in OVIX, kinematic parameters such as velocity (except curvilinear velocity, VCL), trajectory [linearity (LIN), straightness (STR), wobble (WOB)], amplitude of lateral head displacement (ALH) and beat/cross frequency (BCF) were higher than in INRA and BIL. No significant differences in pregnancy rate were detected between INRA (62.6%) and OVIX (58.9%). In conclusion, liquid storage at 5 °C with OVIX extender is an interesting option since non-animal components are used, and this extender offers similar in vitro and in vivo efficacy as other extenders containing animal components.

Liquid storage of dromedary camel semen in different extenders

This study was conducted to assess the effects of commercial extenders and storage temperature on dromedary camel sperm quality during liquid preservation. In Experiment 1, ejaculates (n = five males; replicated seven times) were split and diluted with synthetic (OPTIXcell, EquiPlus, INRA96, Bioxcell or AndroMed; Experiment 1a) or egg-yolk based (Biladyl, Green buffer or Triladyl; Experiment 1b) extenders and stored for 48 h at 4 °C. In Experiment 2, split ejaculates (n = five males; replicated six times) were used to directly compare Green buffer, OPTIXcell and Triladyl extenders over 48 h of storage at 4 °C. Ejaculates collected in Experiment 3 (n = five males; replicated five times) were diluted with Green buffer or Triladyl before chilled storage for 48 h at 4 or 15 °C. Sperm kinematics, viability and acrosome integrity were assessed during liquid storage. In Experiment 1a, there was the greatest total sperm motility (TM) in the OPTIXcell group following 24 and 48 h of storage, while in Experiment 1b, there was the greatest TM after 48 h of storage with Triladyl and Green buffer. In Experiment 2, there were greater TM and viable acrosome intact spermatozoa in the Triladyl and Green buffer than with OPTIXcell group. In Experiment 3, there was a greater TM in the Triladyl than Green buffer group at 24 and 48 h of storage regardless of storage temperature (which had no effect on sperm quality). In conclusion, camel sperm have greater viability when preserved in liquid form for 48 h following dilution with Triladyl and storage at either 4 or 15 °C.

Influence of sperm filtration and the addition of glycerol to UHT skimmed milk- and TEST-based extenders on the quality and fertilizing capacity of chilled ram sperm

The poor fertility of ram semen stored chilled for long periods has encouraged the development of protocols designed to improve the kinetic vigour and cervical barrier-crossing capacity of sperm. The present work evaluated the effect of sperm selection with Sephadex filtration and the supplementation of 2% glycerol (GLY) to extenders based on ultra-heat-treated skimmed milk (UHT) or Tris-Tes-Glucose (TEST) on ram sperm kinetic parameters, plasma membrane integrity, acrosome integrity, mitochondrial function and fertilizing ability, over long chilling times. The results showed that for non-filtered semen, values for progressive sperm motility (%PSM), straight line velocity (VSL, μm/s) and the percentage of sperm with an intact plasma membrane/intact acrosome/a high mitochondrial function index (%IPIAHM) at all times up to 96 h of chilling were higher when the UHT extender (P < 0.01) was used compared to TEST extender irrespective of the presence of GLY. When semen was previously filtered with Sephadex, the addition of GLY to the UHT extender improved total motility (%TM), the %PSM and the VSL at 96 h compared to all other treatments (P < 0.01). The best results of all were obtained with non-filtered semen and UHT either with or without GLY. Heterologous IVF using zona-intact bovine oocytes was used to assess the fertilizing capacity of non-filtered fresh (FS0), chilled-for-24 h (CS24) or chilled-for-48 h (CS48) ram semen diluted in UHT extender (GLY-free). Heterologous IVF showed that ram sperm, either FS0, CS24 or CS48, were equally capable of penetrating zona pellucida intact bovine oocytes, leading to pronuclear formation and hybrid embryo cleavage (46.3 ± 3.2; 48.8 ± 3.2; and 43.3 ± 3.5, respectively). No differences were seen with respect to fresh sperm in terms of sperm binding, penetration, polyspermy, pronucleus formation or cleavage rates (P > 0.05). In conclusion, neither Sephadex filtration nor addition of glycerol provided extra benefits to ram sperm chilled up to 96 h. Chilled, non-filtered sperm extended with UHT without GLY showed better sperm functionality than did similar sperm extended with TEST extenders. Indeed, sperm diluted in UHT extender, maintained fertilizing ability up to 48 h.

Sperm quality in frozen beef and dairy bull semen

BACKGROUND

There is speculation that beef bull semen quality is inferior to that of dairy bulls although few scientific studies are available in the literature. The aim of this study was to evaluate sperm quality in beef bull semen and to determine which parameters could be indicative of fertility after insemination. Sperm quality, assessed by computer assisted sperm motility analysis and flow cytometric evaluation of membrane integrity, levels of reactive oxygen species, mitochondrial membrane potential, acrosome status and DNA fragmentation index, was evaluated in beef and dairy bull semen.

RESULTS

For beef bulls, normal morphology (r = 0.62, P < 0.05) and WOBBLE (r = 0.57, P < 0.05) were significantly correlated with 56-day non-return rate, whereas sperm quality was not significantly correlated with the fertility index score for dairy bulls. Membrane integrity (46 ± 8.0% versus 40 ± 11%, P < 0.05), normal morphology (87 ± 6% versus 76 ± 8%; P < 0.05), and high respiratory activity (52 ± 13 versus 12 ± 4%; P < 0.001) were higher for dairy bulls than for beef bulls. The DNA fragmentation index was lower for dairy bull spermatozoa than beef (3.8 ± 1.1% versus 6.1 ± 2.9%; P < 0.01), whereas some sperm kinematics were higher. Multivariate analysis indicated that type of bull (beef versus dairy) had an impact on sperm quality.

CONCLUSIONS

Different assays of sperm quality may be needed for appropriate analysis of beef and dairy bull semen. These finding could be important for cattle breeding stations when evaluating semen quality.

A comparison of semen diluents on the in vitro and in vivo fertility of liquid bull semen

The aim of this study was to assess the effect of semen diluent on calving rate (CR) following artificial insemination with liquid bull semen stored for up to 3 d postcollection. In experiment 1, the effect of storing liquid semen maintained at a constant ambient temperature in 1 of 7 different diluents [Caprogen (homemade), OptiXcell, BioXcell, BullXcell, INRA96, NutriXcell, or AndroMed (all commercially available)] on total and progressive motility was assessed on d 0, 1, 2, and 3 postcollection. In experiment 2, the field fertility of liquid semen diluted in Caprogen, BioXcell, or INRA96 and inseminated on d 1, 2, or 3 postcollection was assessed in comparison to frozen-thawed semen (total of n = 19,126 inseminations). In experiment 3, the effect of storage temperature fluctuations (4 and 18°C) on total and progressive motility following dilution in Caprogen, BioXcell, and INRA96 was assessed on d 0, 1, 2, and 3 postcollection. In experiment 1, semen stored in Caprogen, BioXcell, and INRA96 resulted in the highest total and progressive motility on d 1, 2, and 3 of storage compared with OptiXcell, BullXcell, NutriXcell, and AndroMed. In experiment 2, an effect of diluent on CR was found as semen diluted in BioXcell had a lower CR on d 1, 2, and 3 of storage (46.3, 35.4, and 34.0%, respectively) in comparison with Caprogen (55.8, 52.0, and 51.9%, respectively), INRA96 (55.0, 55.1, and 52.2%, respectively), and frozen-thawed semen (59.7%). Effects were found of parity, cow fertility sub-index, as well as the number of days in milk on CR. In experiment 3, when the storage temperature of diluted semen fluctuated between 4 and 18°C, to mimic what occurs in the field (nighttime vs. daytime), BioXcell had the lowest total and progressive motility in comparison to Caprogen and INRA96. In conclusion, diluent significantly affected sperm motility when stored for up to 3 d. Semen diluted in INRA96 resulted in a similar CR to semen diluted in Caprogen and to frozen-thawed semen, whereas that diluted in BioXcell resulted in a decreased CR. Consistent with this finding, semen diluted in BioXcell was less tolerant of temperature fluctuations than that stored in Caprogen or INRA96. Given that it can be used directly off the shelf, INRA96 may be a suitable alternative to Caprogen for the storage of liquid bull semen.

Cryopreservation of bull semen: Evolution from egg yolk based to soybean based extenders

Since the inception of bovine semen cryopreservation, egg yolk and milk based extenders have been used to protect sperm from the detrimental effects of cooling and freezing. In recent years, demand for alternatives to conventional commercial extenders has arisen as the risk of introducing exotic diseases through transporting egg yolk based products has been recognized. Egg yolk can also interfere with sperm evaluation and the presence of particulate material in the extender may reduce fertility. Soybeans contain lecithin, a phospholipid fraction that can substitute for high molecular weight lipoprotein and phospholipids from egg yolk and prevent or ameliorate damage to the sperm plasma membrane that occurs during extension, cooling, and cryopreservation. Soy lecithin based extenders have been evaluated for processing and freezing bovine semen, although extender from soybean milk has not been studied as extensively. Commercially available soy lecithin based extenders are used increasingly but remain under scrutiny and are not universally accepted. With these observations in mind, this review is intended to examine effects of conventional cryopreservation procedures, methods of assessment, and potential for developing soybean extract as an acceptable alternative to traditional egg yolk and milk based extenders for bull sperm cryopreservation.

USO DE DILUENTES E TEMPERATURAS ALTERNATIVAS NA CONSERVAÇÃO PROLONGADA DO SÊMEN DO VARRÃO

Resumo O uso de diluentes adequados é importante para o sucesso de um programa de inseminação artificial. O objetivo deste experimento foi avaliar a eficiência de diluentes alternativos para o sêmen suíno, em diferentes temperaturas (17 e 10 °C). Foram utilizados os diluentes: Beltsville Thawing Solution (BTS); água de coco em pó (ACP®-103) e leite em pó desnatado (LPD). Os 50 ejaculados, foram analisados in natura e após diluição, diariamente, durante os 5 dias de conservação do sêmen (D0 a D4), quanto ao vigor e motilidade espermática. Avaliou-se a integridade do acrossoma e a viabilidade espermática no D0 e D4. Na análise estatística, foram utilizados os testes de Mann-Whitney, Students, Tukey e o qui-quadrado, com intervalo de confiança de 5%. O diluente LPD a 10 °C apresentou motilidade e vigor espermático melhores em relação ao BTS e ACP (10 °C) até D2 e aos tratamentos conservados a 17 °C. A vitalidade e integridade acrossomal, no D0 e D4, foram melhores com LPD a 10 °C, que mostrou ser um bom meio diluente para o sêmen suíno em temperatura mais baixa (10 °C), conferindo uma maior proteção à célula espermática, através de maiores taxas de viabilidade e integridade de acrossoma.