In vitro characteristics of canine spermatozoa subjected to two methods of cryopreservation

Canine sperm vitrification with nonpermeable cryoprotectants and coconut water extender

This study was aimed to assess the efficiency of coconut water extender with addition of soy lecithin and sucrose as nonpermeable cryoprotectants for canine semen vitrification, using a simple method that yields a high survival rate of spermatozoa for clinical use. Twelve ejaculates from 12 adult normozoospermic dogs were collected separately by digital manipulation and only the second semen fraction was used in this study. After evaluation of volume, concentration, viability, total and progressive motility, velocity parameters and morphology, semen was diluted with a coconut water extender (50% (v/v(volume per volume)) coconut water, 25% (v/v) distilled water and 25% (v/v) 5% anhydrous monosodium citrate solution) with addition of soy lecithin and fructose at 1% and 0.25M sucrose until final concentration of 100x10⁶ spermatozoa/ml. After equilibration at 5ºC for 60 minutes, semen was vitrified by "direct dropping method" into liquid nitrogen in spheres with a volume of 30 μl. After a week of storage the spheres were devitrified as three of them were dropped into 0.5 mL of CaniPlus AI medium (Minitüb, Germany), which was previously warmed in a water bath at 42ºC for 2 minutes and evaluated about the above mentioned parameters. It was found that vitrification resulted in a lower percentage of viable sperms, normal morphology, total and progressive motilities (p<0.05), but most of velocity parameters (VCL, VSL, VAP, LIN, ALH and BCF) did not differ (p>0.05) compared to fresh semen samples. In conclusion, our results demonstrate that vitrification with coconut water extender with addition of 1% soy lecithin and 0.25M sucrose as cryoprotectants, has an excellent potential for routine canine sperm cryopreservation.

Does Better Post-Thaw Motility of Dog Sperm Frozen with CLC Mean Better Zona Pellucida Binding Ability?

Even though the search for methods improving cryopreservation of canine spermatozoa led to an improvement of post-thaw quality, fertilizing results after insemination with frozen-thawed semen are still not satisfying. In this study, we focused on modification of spermatozoa membrane fluidity and investigated whether kinematic parameters as assessed by computer-assisted semen analyzer (CASA) can be improved. The primary aim of our study was to investigate whether the use of cholesterol-loaded cyclodextrins (CLC; 0.5 mg, 1 mg, 2 mg) and 2-Hydroxypropyl-ß-cyclodextrin (HBCD; 1 mg) positively influence capacitation status as examined by tyrosinphosphorylation, cholesterol efflux and zona binding assay (ZBA) of spermatozoa. The use of 0.5 mg of CLC increased the percentage of motile, progressive and rapid spermatozoa compared to the control. Addition of HBCD decreased motility and progressive motility of spermatozoa and the population with rapid movement in comparison to the control. The percentage of live spermatozoa without efflux of cholesterol compared to the control was increased when extender with 0.5 mg of CLC was used. There was no change in capacitation status. The zona binding ability of spermatozoa was significantly lower in the group with 0.5 mg of CLC than in the control. In conclusion, these results suggest that improvement of kinematic parameters does not necessarily coincide with better zona pellucida binding ability of spermatozoa.

Molecular Dynamics Simulation of the Oil–Water Interface Behavior of Modified Graphene Oxide and Its Effect on Interfacial Phenomena

Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In this paper, based on the molecular dynamics method combined with the first nature principle, we first determine the magnitude of the binding energy of three different coupling agents—alkylamines, silane coupling agents, and haloalkanes—and analytically obtain the characteristics of the soft reaction. The high stability of alkylamines and graphene oxide modified by cetylamine, oil, and water models was also established. Then, three different chain lengths of simulated oil, modified graphene oxide–water solution, and oil-modified graphene oxide–water systems were established, and finally, the self-aggregation phenomenon and molecular morphology changes in modified graphene oxide at the oil–water interface were observed by an all-atom molecular dynamics model. The density profile, interfacial formation energy, diffusion coefficient and oil–water interfacial tension of modified graphene oxide molecules (NGOs) at three different temperatures of 300 K, 330 K, and 360 K were analyzed, as well as the relationship between the reduced interfacial tension and enhanced oil recovery (EOR).

Freezability of Dog Semen after Collection in Field Conditions and Cooled Transport

Simple Summary

Dog semen freezing is gaining popularity, but it has to be performed in equipped facilities, which can be far from the place where the stud dog lives. To avoid animal movement, it seemed interesting to investigate whether freezing dog semen after 24 or 48 h of cooled transport to an equipped laboratory was possible when semen collection was performed in the field such as in local breeding kennels. The influence of two pre-freezing holding times (i.e., 24 or 48 h) and two holding diluents (solutions used to dilute semen before freezing) was evaluated. Post-thaw morphofunctional sperm features, such as motility, morphological integrity, and ability to bind female gametes, were assessed. No differences between times or diluents were observed, but motility tended to decrease in the samples frozen at 48 h. Since the insemination dose was based on the number of motile spermatozoa, a shorter pre-freezing time is advisable. Yet, considering that the rest of the morphofunctional parameters remained comparable between samples frozen after collection or after 24/48 h of transport, freezing after cooled transport is a good option for avoiding animal stress and for promoting a greater diffusion of semen cryopreservation.

Abstract

Dog semen freezing is gaining popularity, but it has to be performed in equipped facilities, which can be far from the place where the stud dog lives. The aim of this study was to evaluate whether freezing dog semen after 24 or 48 h of cooled transport to an equipped laboratory was possible when semen collection was performed in the field such as in local breeding kennels. Single ejaculates from different dogs (mixed breeds and ages) were collected. In Experiment I, 10 ejaculates were conventionally frozen using the Uppsala method or frozen after 24 or 48 h of storage in a Styrofoam transport box cooled by icepacks. In Experiment II, 10 ejaculates were used to assess the influence of two extenders (Uppsala chilling extender or freezing extender 1) used for semen dilution during the 24 or 48 h storage. Motility, morphology, membrane, and acrosome integrity were analyzed as well as spermatozoa zona-binding ability. No significant differences were observed among the frozen groups, regardless of freezing time (Experiment I) or extender (Experiment II). Motility at thawing, however, decreased in absolute value at 48 h. Freezing of freshly collected semen is the gold standard, but the results obtained in this study prompt the application of freezing after cooled transport for the long-term preservation of dog semen, especially if the transport can be organized in 24 h.

Cryopreservation of dog epididymal spermatozoa by conventional freezing or ultra-rapid freezing with nonpermeable cryoprotectant

This study was aimed to assess the effectiveness of two methods for cryopreservation of dog epididymal spermatozoa, one by conventional freezing (CF) with shortening both equilibration and cooling times, and the other by ultra-rapid freezing (URF) with nonpermeable cryoprotectant. Sixty epididymides were recovered from thirty orchiectomized adult dogs and the sperm samples were retrieved by retrograde flushing using TCG-EY (tris, citric acid, glucose + 20% egg yolk) extender and then 20 pools were conformed. Each pool was divided into 2 aliquots and then cryopreserved by CF and URF methods respectively. The CF method maintained the cooled-pool samples for 2h (1h without and 1h with 5% glycerol) and then were frozen by liquid nitrogen (LN₂) vapors for 2 min. The URF method cryopreserved the cooled-pool samples using TCG-EY+250 mM sucrose, equilibrating during 30 min (5 °C) and submerging 30-μL drops directly in LN₂. The results showed that the URF method produced a lower percentage of total and progressive motilities and acrosome integrity (P < 0.05) than the CF method. However, the kinetic variables (curvilinear and straight-line velocities, straightness, linearity, wobble, amplitude of lateral head displacement, and beat-cross frequency) and plasma membrane integrity did not differ (P > 0.05) between both cryopreservation methods. Unlike the URF method, the width, area and perimeter of sperm head were reduced after the CF method (P < 0.05). In conclusion, despite the low motility achieved after the ultra-rapid freezing method, the similar values of kinetic, viability and head morphometric dimensions to those obtained after conventional freezing, suggest that ultra-rapid freezing with sucrose may be a useful alternative for the cryopreservation of canine epididymal sperm.

Eficiência de duas técnicas de recuperação de espermatozoides epididimários de cães e avaliação seminal pós-criopreservação

RESUMO O objetivo deste trabalho foi avaliar a recuperação de espermatozoides epididimários de cães castrados, utilizando as técnicas de fluxo retrógrado (FR) e flutuação (FL) em diluidor Tris-gema, antes e após a criopreservação. Foram coletados 30 complexos testículo-epididímos (CTE), sendo 15 para FR e 15 para FL, e, logo após a recuperação dos espermatozoides, foram analisadas as alterações morfológicas nessas células espermáticas. Após a adição do diluidor, foram avaliados os parâmetros de motilidade total (MOT) e vigor (V) espermáticos. O sêmen pós-criopreservado foi submetido ao teste de termorresistência nos tempos T0, T30, T60 e T90 minutos, além da avaliação das membranas plasmática e acrossomal por sondas fluorescentes. Não houve diferença estatística entre as técnicas quanto à MOT e ao vigor no sêmen diluído (FR-MOT: 82,3% e V: 3,4; FL-MOT: 79,6% e V: 3,2) e pós-criopreservado (FR-MOT: 34% e V: 2,8; FL-MOT: 30% e V: 2,7). A partir do T30, houve diferença significativa quanto à MOT e ao vigor nas técnicas utilizadas, e o tempo também prejudicou o acrossoma espermático a partir do T30. Conclui-se que as técnicas de recuperação de espermatozoides epididimários de cães castrados, testadas neste trabalho, podem ser utilizadas para refrigeração e criopreservação de sêmen.

In vitro evaluation of Labrador dog spermatozoa cryopreserved in Tris-citric acid-fructose buffer supplemented with different combinations of extracellular and intracellular cryoprotectants

Aim of this study was to compare different combinations of penetrating intracellular CPAs, i.e., glycerol (G), ethylene glycol (EG), propylene glycol (PG), dimethyl formamide (DM), and methyl acetamide (MA) and extracellular [egg yolk (EY), egg yolk plasma (EYP), low-density lipoproteins (LDL), and coconut water (CW)] in Tris-citric acid-fructose buffer (T) for Labrador dog semen cryopreservation. The study was conducted in two parts, first trial was conducted to assess optimum glycerol concentration (5-7%) in TEY and equilibration time (ET, 2-4 hrs) for Labrador dog semen cryopreservation. Secondly, compatibility of 15% TEY, 15% TEYP, 13% TLDL, and 25% TCW with G, DMF, MA, D + M, EG, and PG was evaluated for in vitro sperm function tests. Decline in sperm attributes, i.e., motility, viability, plasma membrane integrity (PMI), and acrosome integrity (AI)) was significantly (p < 0.05) less in 7% TEY-G and 4 h compared to other concentrations and ET at post-thaw. There was significantly (p < 0.05) less decline in sperm attributes in TEY-G, TEYP-G, TLDL-G, TLDL-D, TLDL-EG, and TCW-D extenders compared to other combinations at post-thaw. However, these parameters were significantly (p < 0.05) high in TEY-G and TEYP-G compared to TEYP-D, TLDL-G, TLDL-D, TLDL-EG, and TCW-D extenders at post-thaw. However, decline in motility, viability, PMI, and AI was identical in these seven extenders. This study concluded that glycerol at a concentration of 7% in TEY and 4 h ET were optimum for successful cryopreservation and besides TEY-G, other combinations of protectants may be an alternative for canine semen cryopreservation.

Avaliação in vitro do sêmen criopreservado de cães naturalmente infectados por Leishmania sp

RESUMO O objetivo deste trabalho foi avaliar a qualidade in vitro do sêmen criopreservado de cães naturalmente infectados por Leishmania sp. Foram coletadas amostras de sêmen de 12 cães, sendo seis positivos (GI) e seis negativos (GII) para leishmaniose visceral (LV), semanalmente, totalizando quatro coletas por animal. O sêmen criopreservado foi avaliado pelo teste de termorresistência rápida (TTR), nos tempos zero, 30 e 60 minutos, pela análise computadorizada (CASA) e por meio de sondas fluorescentes; esta última técnica com o intuito de avaliar a integridade das membranas espermáticas. Houve diferença estatística pela técnica de TTR no parâmetro motilidade progressiva, no tempo 0min (68,33% GI e 72,50% GII), e no vigor espermático (2,67 GI e 3,0 GII), no tempo 30min. Quanto ao CASA, houve diferença estatística apenas na motilidade total (27,50% GI e 57,08% GII), embora os demais parâmetros seminais tenham apresentado valores relativos diminuídos nos cães do GI. Nas análises com sondas fluorescentes, foram observadas diferenças estatísticas entre os grupos quanto à integridade das membranas plasmática e acrossomal e ao potencial mitocondrial das células espermáticas. Concluiu-se que a LV pode comprometer a qualidade do sêmen criopreservado de cães parasitados.

Efeito da radiação vermelha de baixa intensidade sobre o sêmen canino criopreservado

O objetivo geral deste trabalho foi analisar o efeito da radiação vermelha de baixa intensidade sobre alguns parâmetros cinéticos do espermatozoide canino criopreservado. Ejaculados de oito cães adultos foram centrifugados, rediluídos em meio tris-gema de ovo com 6% de glicerol, e, posteriormente, fracionados em: T1: incidência de radiação vermelha (660 NM) (Fisioled - Mmoptics - 100mW) por 60 segundos, antes do resfriamento e após a descongelação; T2: incidência somente antes do resfriamento; T3: incidência somente após a descongelação; e T4: sem incidência. Após a descongelação, as amostras foram submetidas ao TTR utilizando-se Sperm Class Analyzer(r). No TTR0, TTR60 e TTR90, não houve diferença entre as variáveis analisadas pelo CASA. Somente no TTR30 os efeitos da incidência da radiação vermelha foram evidentes e significativos em T1 e T2; T1 resultou em baixa MT (12,5 + 10,6%) e T2 determinou o melhor resultado de MT 40,3 + 26,1%. De forma similar T1 apresentou maior número de espermatozoides estáticos (77,5±28,9%) em relação ao T2 (50,6±28%). Concluiu-se que a dupla incidência de radiação vermelha de baixa intensidade antes do resfriamento e após a descongelação teve efeito deletério sobre a motilidade do espermatozoide canino, expressa principalmente aos 30 minutos após descongelação.

Efeito da temperatura de descongelação na integridade de espermatozoides criopreservados de cães

Avaliou-se a influência da temperatura de descongelação na integridade de espermatozoides criopreservados de cães. Foram utilizados reprodutores das raças Basset Hound (n=3) e Rottweiler (n=3), submetidos a colheitas de sêmen por manipulação peniana. As amostras de sêmen foram descongeladas a 37ºC/1min (G1) ou 70ºC/6s (G2) e avaliadas quanto à motilidade progressiva, vigor e integridade do acrossoma após 0, 30 e 60 minutos de incubação (37ºC), e ultraestrutura espermática imediatamente após a descongelação. Em todos os tempos de incubação, a motilidade progressiva dos espermatozoides descongelados a 70ºC por 6s (74,6%) foi mais alta (P<0,05) que a dos descongelados a 37ºC por 1min (64,6%). O vigor espermático não diferiu (P>0,05) entre os grupos, e o porcentual de gametas com acrossomas íntegros foi maior (P<0,05) nos espermatozoides do G1 do que no G2. Lesões ultraestruturais foram identificadas nos espermatozoides descongelados de ambos os grupos, em maior quantidade nos gametas do G2. Conclui-se que amostras congeladas de sêmen de cães devam ser descongeladas a 37ºC por 1min.

Influence of cool storage before freezing on the quality of frozen-thawed semen samples in dogs

The aim of this study was to determinate the semen quality of frozen-thawed samples that were chilled for up to 2 days before freezing. The ejaculates (n = 18) from six dogs were collected, pooled and divided into six aliquots. The first aliquot (C, control) was frozen in liquid nitrogen using a conventional protocol to reach a final concentration of 100 × 10(6) spermatozoa/ml, 20% egg yolk and 5% glycerol. The remaining five aliquots were diluted with a chilled extender (Tris-glucose and 20% egg yolk) and cooled at 4 °C as follows: R1, the semen was cooled for 1 h; R6, the semen was cooled for 6 h; R12, the semen was cooled for 12 h; R24, the semen was cooled for 24 h and R48, the semen was cooled for 48 h. After the chilling period, a second extender was added (Tris-glucose, 20% egg yolk, 10% glycerol and Equex at 1%) to reach a final composition similar to aliquot C, and then, the semen samples (R1, R6, R12, R24 and R48) were frozen in liquid nitrogen. The post-thaw sperm quality was assessed in 30 straws from each experimental group. After freezing-thawing, the total sperm motility (approximately 60-70%) in the semen chilled for up to 48 h did not show any differences from the samples frozen by the conventional cryopreservation method (63.2%). No significant differences were detected in the percentages of abnormal sperm cells among the fresh semen, the control group and the frozen samples after the different cooling times. Finally, the post-thaw percentages of damaged acrosomes showed a very uniform distribution, with mean values ranging between 7% and 10.5%. The results clearly demonstrated that cooling the semen up to 48 h before freezing did not produce a decrease in the semen quality when was compared with semen frozen by a traditional procedure.

Comparison of sperm quality and DNA integrity in mouse sperm exposed to various cooling velocities and osmotic stress

The first objective was to compare sperm quality following conventional manual sperm freezing (cryovials held 1, 2, 3, and 4 cm, respectively, above liquid nitrogen (LN(2)) for 10 min, resulting in cooling velocities of approximately -14.9, -10.1, -6.6, and -5.1 °C/min, respectively), and cooling velocities of -5, -20, -40, and -100 °C/min in a programmed automated freezer, for sperm recovered from CD-1, B6129SF1, and C57BL/6NCrlBR mice. Furthermore, using these strains, as well as 129S/SvPaslco, and DBA/2NCrlBR mice, the second objective was to determine the effects on DNA integrity of sperm exposed to hyposmotic (1 mOsm/L) and hyperosmotic (2400 mOsm/L) solutions, compared to an isosmotic control (300 mOsm/L). For freezing above LN(2) or in an automated freezer, 2 cm above LN(2) and -100 °C/min, respectively, were optimal (P < 0.05-0.01), with no significant differences between these two approaches for post-thaw progressive motility, DNA integrity, and in vitro rates of fertilization and blastocyst formation. Both manual and automated freezing techniques increased post-thaw sperm DNA fragmentation (P < 0.01); the DNA integrity of post-thaw sperm was significantly affected by cooling velocity and strain background. Relative to isosmotic controls, a hyposmotic solution was more deleterious (P < 0.05-0.01) to sperm DNA integrity than a hyperosmotic solution for CD-1, B6129SF1, C57BL/6, and DBA mice (there were strain-dependent differences). In conclusion, optimization of freezing distance and cooling velocity (manual and automated freezing, respectively) were significant factors for efficient cryopreservation and re-derivation of mice from frozen-thawed sperm. Additionally, osmotically-driven volume changes in mouse sperm increased DNA fragmentation, with susceptibility affected by background strain.

A scanning electron microscopy study of frozen/thawed dog sperm during in vitro gamete interaction

The aim of this work was to study the effects of cryopreservation on the binding and penetration of dog spermatozoa to the zona pellucida (ZP) by scanning electron microscopy (SEM). The sperm-rich fraction of six ejaculates from five dogs was divided into two aliquots and washed by centrifugation. One aliquot was processed as fresh control sample and the other aliquot frozen in Tris-fructose extender. Gamete interaction was assessed using in vitro matured bitch oocytes, which were co-incubated for up to 3 h. At hourly intervals after the start of co-incubation, in vitro fertilized (IVF) oocytes were processed by SEM. The results were analysed statistically using the anova test. Differences in binding and penetration of the spermatozoa to the ZP occurred; a lower proportion of oocytes with spermatozoa bound to ZP was observed using frozen sperm (p < 0.05) than with fresh sperm (61%, 57% and 53% vs 42%, 40% and 44% at 1, 2 and 3 h, respectively). The percentage of ZP penetration by fresh sperm was directly proportional to the time of co-incubation (9%, 25% and 34%; p < 0.05); in contrast, no differences were observed in the penetration rate with frozen-thawed sperm (21%, 17% and 21%). More acrosome reacted sperm were observed in frozen sperm than in fresh sperm on the surface of the ZP. The differences in the percentage of binding and penetration between fresh and frozen sperm during the co-culture could indicate that the time course of penetration is faster in frozen-thawed dog spermatozoa than in fresh sperm, but that fresh spermatozoa can penetrate more oocytes over a given period of time, which may be related to their reacted or non-reacted initial status.

Evaluation of Fertilizing Potential of Frozen-thawed dog Spermatozoa Diluted in ACP-106�using an In Vitro Sperm?Oocyte Interaction Assay

The aim of present study was to evaluate frozen canine semen with ACP-106 (Powder Coconut Water) using an in vitro sperm--oocyte interaction assay (SOIA). Ten ejaculates from five stud dogs were diluted in ACP-106 containing 20% egg yolk, submitted to cooling in a thermal box for 40 min and in a refrigerator for 30 min. After this period, a second dilution was performed using ACP-106 containing 20% egg yolk and 12% glycerol. Samples were thawed at 38 degrees C for 1 min. Post-thaw motility was evaluated by light microscopy and by using a computer aided semen analysis (CASA). Plasma membrane integrity and sperm morphology/acrosomal status were evaluated by fluorescent probes (C-FDA/PI) and Bengal Rose respectively. Moreover, frozen-thawed semen was analysed by a SOIA. Subjective post-thaw motility was 52.0 +/- 14.8% and it was significant higher than the total motility estimated by CASA (23.0 +/- 14.8%) because this system considered the egg yolk debris as immotile spermatozoa. Although normal sperm rate and acrosomal integrity evaluated by Bengal Rose stain was 89.6 +/- 3.1% and 94.3 +/- 3.1%, respectively, post-thaw percentage of intact plasma membrane was only 35.1 +/- 14.3%. Regarding SOIA, the percentage of interacted oocytes (bound, penetrated and bound and/or penetrated) was 75.3%. Using regression analysis, it was found significant relations between some CASA patterns and data for SOIA. In conclusion, the freezing-thawing procedure using ACP-106 was efficient for maintain the in vitro fertility potential of dog spermatozoa.

A, Henry M. In vitro evaluation of canine spermatozoa cryopreserved in different extenders

The efficacy of three extenders, tris-egg yolk-5% ethylene glycol (T1), lactose-egg yolk-5% ethylene glycol (T2) and lactose-egg yolk-5% dimethyl formamide (T3) on preserving the viability of post-thawing canine spermatozoa was evaluated. Three ejaculates per dog were obtained of five animals. The semen was packaged in 0.5ml straws and cooled to 4°C for 120min. The straws were frozen 4cm above the nitrogen level for 15min and thawed in water-bath at 37°C for 60sec and at 75°C for 7sec. Progressive motility and vigour were evaluated immediately after thawing (time 0) and at 30, 60, 90 and 120min. Structural and functional integrity of plasma membrane of the spermatozoa were evaluated, respectively, by fluorescent staining probes and hypoosmotic swelling test. Lactose-egg yolk based extenders showed better cryoprotectant capability and dimethyl formamide was an alternative cryoprotectant agent for dog sperm cells.

Characteristics of captive Japanese black bears (Ursus thibetanus japonicus) semen collected by electroejaculation with different voltages for stimulation and frozen-thawed under different conditions

The Japanese black bear (Ursus thibetanus japonicus) is an endangered species in some areas of Japan, and semen collection and cryopreservation are important means to preserve genetic resources and prevent extinction. The aim of the present study was to improve the methods for electroejaculation and cryopreservation in these bears. We collected the semen from captive mature Japanese black bears during the mating season by the electroejaculation method using maximum stimulus voltages of 10 V (n=9) and 7 V (n=15), and compared the characteristics of fresh semen after collection. None of the variables examined (i.e. total sperm count, motility, viability, morphology, and rate of urine contamination) were statistically different between the two electro-stimulus voltages. After the semen obtained was cryopreserved, the effects of three different diluents (egg yolk-TRIS-citrate-glucose, egg yolk-TRIS-citrate-fructose, and egg yolk-TRIS-citrate-fructose-lactose-raffinose; n=10) and two different incubation times (1-1 and 3-0 h of cooling-glycerol equilibration times; n=12) on frozen-thawed spermatozoa. None of the variables examined (i.e. motility, viability and morphology) were statistically different among the three diluents and between the two incubation times. The results indicate that, in the collection and cryopreservation of Japanese black bear semen: (1) a maximum voltage of 7 V may be enough to obtain ejaculates; (2) the three diluents examined were useful; and (3) glycerol equilibration time may be omitted with prior cooling for 3h.

Effects of semen extender and semen processing on motility and viability of frozen-thawed dog spermatozoa

The aims of the present study were, to assess the effects of semen centrifugation, two different diluents and two different freezing methods on post-thaw semen quality in canine semen, and to elucidate the interdependence of these parameters. For this purpose, the sperm-rich fractions of ejaculates from 12 healthy male beagles were divided into four aliquots. Two aliquots were centrifuged and resuspended with two TRIS-egg yolk based extenders: with Uppsala and Gill extender (Gill). The diluents differed in the concentration of glycerol and in the admixture of Equex STM paste (Nova Chemical Sales Inc., Scituate, MA, USA). Diluted semen was frozen either in a styrofoam box or with a computerized freezing machine and an optimized freezing curve (IceCube 1,810; Sy-Lab, Purkersdorf, A). The change in temperature inside the straws was measured during the freezing procedure. Thawed semen samples were assessed for motility and viability (SYBR-14/PI) using the computer assisted sperm analyzer SpermVision (Minitüb, G) and a modified triple staining technique (flow cytometry). Deep freezing in the machine resulted in better motility and viability than in the box. The combination centrifugation-Uppsala extender-machine was superior to all other combinations, which was most evident after storage at +5 degrees C for 7 h (motility: 53.1%, viability: 64.9%). Post-thaw longevity and progressive motility were significantly improved by the use of the here introduced freezing curve. This was shown to be partly caused by less pronounced fluctuations of temperature inside the straws when compared to box-freezing.

Comparison of two dilution rates on canine semen quality after cryopreservation in a coconut water extender

The objective of the present study was to evaluate the effect of sperm dilution (one part semen:one part extender or at 200 x 10(6) spermatozoa/mL) using a coconut water extender on the post-thaw sperm quality. Twelve ejaculates were collected from six dogs. Semen was divided into two aliquots, one for dilution one part semen:one part extender (group 1) and another for a concentration of 200 x 10(6) spermatozoa/mL (group 2). Semen was initially extended at 37 degrees C at a proportion of one part semen:half part extender (1:1/2) for group 1 (A-fraction). For group 2, the volume for a concentration of 200 x 10(6) spermatozoa/mL was calculated and a half of this volume was used for the initial dilution (A-fraction, 37 degrees C). Coconut water extender containing 20% egg yolk was used for this initial dilution in both groups. After dilution, the semen was cooled for 40 min in a thermal box (15 degrees C) and for 30 min in a refrigerator. The other half of the extender (B-fraction) containing egg yolk and glycerol (12%) was added to semen in both groups. Subsequently, the final concentration of glycerol in the extender was 6%. Ejaculates were frozen in 0.25 mL straws 5 cm above the surface of liquid nitrogen and stored at -196 degrees C. After 1 week, straws were thawed at 37 degrees C for 1 min and the microscopic criteria were evaluated. The dilution method had no influence on sperm motility, vigor and normal spermatozoa (71.4 compared with 67.7%). There was no effect of dog, ejaculate within male on post-thaw semen quality. Moreover, there was not a male x treatment interaction. Both treatments were efficient in preserving sperm quality.

Influence of Temperature during Glycerol Addition and Post-thaw Dilution on the Quality of Canine Frozen Semen

Contents The aim of the present study was to compare the influence of room temperature (27 degrees C) and 4 degrees C during glycerol addition on canine semen cryopreservation and verify the effect of different post-thawing dilutions on canine semen. Ten ejaculates from five stud dogs were collected by digital manipulation. Semen samples were evaluated and further divided into two aliquots. The first aliquot was extended in Tris-egg yolk-glycerol at 27 degrees C and the second one received glycerol at 4 degrees C. Samples were frozen and stored in liquid nitrogen. After 1 week, samples were thawed and submitted to evaluations of progressive sperm motility, morphology, acrosomal integrity, hypo-osmotic swelling (HOST) and thermoresistance tests. For thermoresistance test, aliquots were divided in two portions: one portion was kept undiluted (1 : 0) and the other one was diluted in a 1 : 4 ratio (one part semen to four parts extender). No differences were observed between temperatures for glycerol addition regarding seminal parameters evaluated. Furthermore, post-thawing dilutions demonstrated similar effect on canine semen longevity. Correlations among post-thaw sperm motility and HOST and results from thermoresistance test were observed for both temperatures for glycerol addition. In conclusion, glycerol could be added to canine semen at room temperature (27 degrees C) or at 4 degrees C. Moreover, there is no need to extend canine semen after thawing for the thermoresistance test, but if we need to increase the inseminating volume for artificial inseminations, the addition of extender will not damage the semen.

Comparison between different dilution rates on canine semen freezing using Tris-buffer with the addition of egg-yolk and glycerol

Standardized sperm concentration and volume:volume extension were compared as dilution rates for canine semen freezing. Six proven stud dogs were submitted to two seminal collections by manual stimulation. Semen was evaluated and extended in tris plus egg-yolk and glycerol according to two different dilution rates. The first one was based on a standardized sperm concentration of 200x10(6) spermatozoa/ml and the second was a volume:volume extension at a proportion of one part semen to one part extender. Semen was frozen, stored in liquid nitrogen and thawed after one week. Sperm motility and vigor were appraised after each stage of the process and at 15 and 30min post-thawing. Sperm morphology was analyzed after collection and thawing. No differences were observed between treatments after thawing regarding sperm motility and vigor, normal sperm morphology rate or longevity. Both dilution rates can be efficiently used for canine semen freezing.

Influence of extender, freezing rate, and thawing rate on post-thaw motility, viability and morphology of coyote (Canis latrans) spermatozoa

The objective of this study was to examine the post-thaw effects of three cryoprotective extenders (Tris-fructose-citric acid extender, Tris-glucose-citric acid extender, and lactose extender), three linear freezing rates (-1, -6, and -20 degrees C/min), and three thawing rates (37 degrees C water bath for 120s, 60 degrees C water bath for 30s, and 70 degrees C water bath for 8s) on coyote spermatozoa. After thawing, the findings supported that cryopreservation of coyote (Canis latrans) spermatozoa frozen at a moderate freezing rate (-6 degrees C/min), in either a Tris-fructose or Tris-glucose extender, and thawed at a slow rate (37 degrees C water bath for 120s) or moderate rate (60 degrees C water bath for 30s), resulted in a more vigorous post-thaw motility (range, 57.5-44.0%) and viability (range, 64-49.6%) with the least amount of morphological and acrosomal abnormalities.

New techniques for the assessment of canine semen quality: A review

Until recently, canine semen assessment was routinely performed by conventional light microscopic techniques. The limitations of these methods include subjectivity, variability, the small number of spermatozoa analyzed, and poor correlation with fertilizing potential. The last decade, several new in vitro techniques have been introduced for canine semen assessment that enable a more detailed evaluation of several sperm characteristics. Numerous fluorescent staining techniques have been developed for the evaluation of specific sperm characteristics and functions, including plasma membrane integrity, capacitation status and the acrosome reaction. By combining fluorescent stains, several functional sperm characteristics can be assessed simultaneously. Moreover, by means of flow cytometry, large numbers of fluorescently labelled spermatozoa can be analysed in a short interval. Following thorough standardization and validation, computer-assisted sperm analysis systems provide objective and detailed information on various motility characteristics and morphometric dimensions that cannot be identified by conventional light microscopic semen analysis. In vitro assays, evaluating the capacity of canine spermatozoa to bind to the zona pellucida or oviductal explants, or to penetrate the oocyte, provide additional information on canine gamete interaction that may be useful in predicting the fertilizing potential of spermatozoa. Although substantial improvements have been made in canine semen assessment, surprisingly few parameters were correlated with in vivo fertility. Therefore, further research is required to determine which sperm characteristics are of clinical value for predicting the in vivo fertility in dogs.

Cryopreservation of semen in the dog: use of ultra-freezers of −152 °C as a viable alternative to liquid nitrogen

This experimental work was carried out to validate the use of a -152 degrees C ultra-low temperature freezer to freeze and store canine semen. The semen of three dogs was pooled and processed to obtain a final dilution with a concentration of 100 x 10(6) spermatozoa/mL, glycerol at 5% and Equex at 0.5%. Then, four freezing protocols were tested to evaluate the cryosurvival of sperm at 1, 7, 30, 60 and 120 days after freezing: (I) semen was frozen and stored in liquid nitrogen; (II) semen was frozen in liquid nitrogen and stored in the ultra-low freezer at -152 degrees C; (III) semen was frozen in the vapour of liquid nitrogen and stored in the ultra-low freezer at -152 degrees C; (IV) semen was frozen and stored in the ultra-low freezer at -152 degrees C. Data were statistically analyzed by repeated measures analysis of variance to determine the effect of the freezing protocol and time on the sperm characteristics assessed. The percentages of sperm motility and of dead/live spermatozoa were similar throughout the experimental period, with no significant differences (P < 0.05) to be observed between four different freezing techniques tested. At 120 days after freezing, the percentage of abnormal cells and the percentage of sperm cells with abnormal acrosome were not significantly different between the freezing techniques. Although the number of dogs used was slightly low, in vitro results of this preliminary study showed that the use of ultra-freezers at -152 degrees C to freeze and store canine semen could be a viable alternative to liquid nitrogen.

Zona pellucida binding ability and responsiveness to ionophore challenge of cryopreserved dog spermatozoa after different periods of capacitation in vitro

The present study was aimed to evaluate the functional status of cryopreserved dog spermatozoa after different periods (2, 8 and 24 h) of capacitation in vitro. Sperm motility, viability and binding capacity to the zona pellucida of canine oocytes derived from frozen-thawed ovaries were evaluated at each time point. Sperm viability was assessed by flow cytometry using the Ca(2+)-sensitive indicator Fluo 3 AM and PI, to simultaneously detect the proportion of live spermatozoa and the existence of live sperm subpopulations with different intracellular Ca(2+) content. In addition, the acrosome reaction frequency in ionophore-treated aliquots of spermatozoa incubated in capacitating (CCM) versus non-capacitating (NCM) medium, were evaluated by using eosin-nigrosin staining at the same time intervals. The number of spermatozoa bound to the zona pellucida decreased in about 50% (from 18.61 +/- 14.40 to 7.7 +/- 6.97) when sperm incubation was prolonged from 2 to 8h, however, sperm motility, viability and the subpopulation of live spermatozoa with higher intracellular Ca(2+) concentration decreased in lower extent (10-15%). In CCM-incubated samples, the rate of acrosomal exocytosis in response to ionophore challenge was high (>80%), independently of the evaluation period. NCM-incubated sperm were not affected by ionophore treatment, however, their intracellular Ca(2+) concentration was no different than that observed in CCM-incubated spermatozoa. It was concluded that, after being capacitated, motile and viable spermatozoa seem to lose their ability to bind to the zona pellucida, but this loss is not accompanied by a reduced response to ionophore challenge and it may not be related with changes in the intracellular Ca(2+) concentration of spermatozoa.

Effects of Final Dilution Rate, Sperm Concentration and Times for Cooling and Glycerol Equilibration on Post-Thaw Characteristics of Canine Spermatozoa

This study re-evaluated a protocol for cryopreservation of canine semen. Semen from 4 beagle dogs was pooled, concentrated by centrifugation and adjusted to increasing sperm concentrations by adding back seminal plasma. The prepared or original semen was diluted with an extender (Egg yolk-Tris-citrate-glucose) and cooled to 4 degrees C (cooling), followed by a second dilution with the same extender including glycerol, equilibrated at 4 degrees C (equilibration), then stored in liquid nitrogen. The semen was diluted for frozen samples having a fixed sperm concentration with increasing dilution rates or for those having the reverse combinations. Various dilution rates of 2.5-10 folds or sperm concentrations of 0.25-2.5 x 10(8)/ml had no significant effect on post-thaw sperm characteristics. When cooling was done for different times (0-26 hr) with glycerol equilibration for 1 hr, post-thaw characteristics were better at 2 and 3 hr of cooling, while various times for equilibration (0-4 hr) with cooling for 3 hr had no effect. These results suggest that different dilution rates and sperm concentrations within the ranges tested may not affect the post-thaw sperm characterisitics and that sufficient time for cooling may be essential but a specific equilibration time may not necessarily be required.

Quality of canine semen submitted to single or fractionated glycerol addition during the freezing process

Glycerol is the cryoprotector most frequently used to freeze semen from different species. The objective of the present study was to compare the effect of single and fractionated glycerol addition on canine semen quality after thawing. Sperm fractions from 12 stud dogs were collected, evaluated, extended in Tris plus egg-yolk and separated into two aliquots to which glycerol was added in one step (single) or in three steps at 5-min intervals (fractionated). Semen was frozen and stored in liquid nitrogen and thawed after 1 week. A thermoresistance test was performed over a period of 120 min at 37-39 degrees C to evaluate the percentage of mobile spermatozoa (motility) and the status of motility (vigor) after thawing. There were no significant differences between the two methods of glycerol addition-immediately after thawing, and during the thermoresistance test-in sperm motility, vigor or morphology. A significant reduction in motility and vigor was found at 15 min after thawing and these parameters continued to decline until 120 min. In conclusion, glycerol can be added to canine semen in single or fractionated manner, but the single addition method is the easiest and the most practical to use.

Evaluation of glucose as a cryoprotectant for boar semen

Fertility parameters of boar spermatozoa were evaluated in vitro, after freeze-thawing the semen in three different extenders containing permeable and non-permeable cryoprotectants: A (111.0 mM Tris, 31.4 mM citric acid, 185.0 mM glucose, 20 per cent egg yolk, 3 per cent glycerol and 100 iu/ml penicillin G); B (200 mM Tris; 70.8 mM citric acid, 55.5 mM glucose, 20 per cent egg yolk, three per cent glycerol and 100 iu/ml penicillin G); C (200 mM Tris, 70.8 mM citric acid, 55.5 mM fructose, 20 per cent egg yolk, 3 per cent glycerol and 100 iu/ml penicillin G). The freeze-thawing techniques were the same for each extender. Eight ejaculates from four boars were obtained; the sperm-rich fraction of each ejaculate was extended in each of the three media at a final concentration of 400 x 106 sperm/ml, loaded into 0.5 ml straws and frozen at a rate of 30 degrees C/minute to -196 degrees C. The straws were thawed at 60 degrees C for eight seconds. Sperm motility, acrosomal integrity and in vitro sperm penetration through the zona pellucida of gilt oocytes matured in vitro were evaluated. The motility of unfrozen spermatozoa was 93.1 per cent compared with 60.7 per cent, 48.2 per cent and 35 per cent for sperm frozen in extenders A, B and C respectively; these values were all significantly different (P<0.05). There was no significant decline in sperm motility after incubation for 30 minutes in extender A, but there were significant decreases in sperm motility after 30 minutes of incubation in B and C. The percentage acrosomal integrities were 97.2 per cent for the control and 45.5 per cent, 30.3 per cent and 16.8 per cent for the frozen-thawed spermatozoa in extenders A, B and C respectively. The results of the in vitro penetration assay were 80.7 per cent when using control spermatozoa, and 42.2 per cent, 18.4 per cent and 3.3 per cent when using frozen-thawed spermatozoa in extenders A, B and C respectively

Use of the Sperm Quality Analyzer (SQA II-C) for the assessment of dog sperm quality

In the present study, an automated system for sperm analysis, the Sperm Quality Analyzer (SQA II-C), was tested as a potential tool for the assessment of dog sperm quality. In the first experiment the device displayed a good repeatability of measurements for semen of medium and high quality, as evidenced by a low coefficient of variance (CV; 0.08), whereas a high CV (0.46) was obtained for one dog with semen of inferior quality. In the second experiment, seven different sperm concentrations (25-300 x 106/ml), obtained by dilutions in Hepes-TALP medium were stored for 48 h at room temperature. A concentration dependent increase in sperm motility index (SMI) was shown, reaching a plateau at 150 x 106 spermatozoa/ml. For all sperm concentrations, the SMI value decreased significantly after 24 h, indicating the importance of sperm motility for SMI values. For sperm concentrations lower than 150x106/ml, highly significant correlations [r=0.80;p<0.05] were established between SMI values on one hand and sperm concentration, and semen parameters expressing the overall semen sample quality on the other hand (experiment 3) while non-significant or low correlations were found between SMI values and other individual sperm parameters. In experiment 4, significantly high correlations (r=0.97) were found between mean SMI values and post-thaw motility and progressive motility assessed subjectively. In conclusion, our study indicates that both motility and concentration largely influence SMI values and that the SQA II-C saturates at 150 x 106 fresh spermatozoa/ml. In our opinion, the SQA II-C may be a useful and objective device to assess the post-thaw motility of dog sperm.

Recovery of motile, membrane-intact spermatozoa from canine epididymides stored for 8 days at 4 degrees C

The purpose of this study was to determine how long canine spermatozoa remain motile and with intact membranes when maintained within epididymides stored at 4 degrees C, and to determine whether such stored spermatozoa are able to bind to canine zonae pellucidae. Testes with attached epididymides, obtained from 32 dogs (26 purebred; six mixed breeds) at orchiectomy, were refrigerated at 4 degrees C, and spermatozoa were collected from caudae epididymides at nine time intervals ranging from 5 to 192 h. The effects on spermatozoa that had been refrigerated within epididymides for various times were determined by assaying sperm motility, integrity of plasma membranes and of acrosomes, and measuring binding of membrane-intact spermatozoa to canine zonae pellucidae. Membrane integrity was assessed using a double fluorescent dye, and acrosome integrity by staining with Pisum sativum agglutinin. For the zona-binding assay at various refrigeration time points, duplicate sets of six oocytes each, isolated from ovaries retrieved at elective ovariohysterectomy, were placed into 100 microl droplets of sperm capacitation medium containing 5 x 10(6) spermatozoa/ml. One minute later, oocytes were rinsed vigorously by pipetting, and then incubated for 1 h at 38.5 degrees C in a humidified atmosphere of 5% CO2 in air; the number of membrane-intact spermatozoa bound to zonae were counted. There was no significant decrease in membrane integrity and acrosome integrity of spermatozoa recovered from epididymides stored at 4 degrees C within the first 48 h of refrigeration. In contrast, sperm motility decreased significantly within the first 5 h of refrigeration (P < 0.05), but then declined more gradually thereafter. Some spermatozoa recovered from epididymides that had been refrigerated for 192 h retained their capability to bind to zonae pellucidae, although the mean number of refrigerated spermatozoa (0.4) bound to zonae was less than that of fresh samples (9.0). Membrane integrity of spermatozoa recovered from epididymides refrigerated for various times was highly correlated (r = 0.88) with sperm motility. Even after storage for 192 h (8 days) at 4 degrees C, motile spermatozoa could be recovered from the epididymides, and such refrigerated spermatozoa were capable of binding to zonae. We interpreted these data to indicate that it might be possible to recover functional spermatozoa from postmortem specimens of domestic and nondomestic canids.

Qualidade espermática do sêmen criopreservado de cães: II - Efeito do protocolo de resfriamento

Estudou-se o efeito de dois protocolos de resfriamento do sêmen de cães sobre a qualidade espermática in vitro, após sua criopreservação. Utilizaram-se três machos e realizaram-se cinco coletas em cada um deles. Os procedimentos de resfriamento foram realizados em um congelador de células (biocool) e em caixa de isopor. Foram avaliadas a motilidade, o vigor espermático, a integridade da membrana plasmática (teste hiposmótico), a integridade do acrossoma e a longevidade espermática (teste de termo-resistência). A comparação entre os protocolos de resfriamento mostrou que não houve diferença (P>0,05) entre a caixa de isopor e o biocool logo após o resfriamento. Após a descongelação os resultados foram semelhantes entre os protocolos, observando-se diferença (P<0,05) apenas na motilidade espermática e no teste de termo-resistência (TTR), os quais foram superiores na caixa de isopor.

Qualidade espermática do sêmen criopreservado de cães: I - efeito do meio diluidor

Estudou-se o efeito de dois meios diluidores, Tris-citrato-gema de ovo e Tes-Tris, sobre a qualidade espermática in vitro após criopreservação do sêmen de cães. Utilizaram-se três machos e realizaram-se cinco coletas em cada um deles. Foram avaliadas a motilidade, o vigor espermático, a integridade da membrana plasmática (teste hiposmótico), a integridade do acrossoma e a longevidade espermática (teste de termo-resistência). O meio diluidor Tris-citrato-gema de ovo foi superior (P<0,05) ao meio Tes-Tris por ter apresentado valores em torno de 15% mais altos após a congelação/descongelação do sêmen nos testes de termo-resistência e hiposmótico e nas avaliações da integridade do acrossoma, da motilidade e do vigor espermático

Effects of Equex, one- or two-step dilution, and two freezing and thawing rates on post-thaw survival of dog spermatozoa

The objectives of the present study were to evaluate the effects of adding Equex to a TRIS-extender, diluting the semen in 1 or 2 steps, freezing according to 2 methods, thawing at 2 rates, and the interactions between these treatments, on the post-thaw survival of dog spermatozoa at 38 degrees C. Ten ejaculates were obtained from 8 dogs. Each ejaculate was centrifuged, and the seminal plasma was discarded. Each sperm pellet was diluted with 2 mL of a TRIS-glucose-egg yolk extender containing 3% glycerol (Extender 1 [Ext-1]). Ejaculates were then pooled (9 x 10(9) spermatozoa), and Ext-1 was added to obtain 200 x 10(6) spermatozoa/mL. The semen pool was carefully mixed and divided into aliquots, and processed according to a 2 x 2 x 2 x 2 factorial design to evaluate the effects of 1) adding the same volume of a second TRIS-glucose-egg yolk extender with 7% glycerol that contained (Ext-2-E) or didn't contain (Ext-2) 1% of Equex STM Paste (final concentration of spermatozoa 100 x 10(6) spermatozoa/mL, glycerol 5%, Equex 0% [Ext-2] or 0.5% [Ext-2-E]); 2) diluting the semen in 1 step (adding Ext-2 or Ext-2-E before equilibration) or in 2 steps (adding Ext-2 or Ext-2-E after equilibration, just before the freezing operation); 3) freezing the straws horizontally in a styrofoam box 4 cm above liquid nitrogen (LN2) or by lowering them vertically into a LN2 tank in 3 steps; and 4) thawing at 70 degrees C for 8 sec or at 37 degrees C for 15 sec. A total of 16 treatment combinations were evaluated. Sperm motility was evaluated after thawing and at 1-h intervals during 7 h of incubation at 38 degrees C by subjective examination and by using a CASA-system. Plasma membrane integrity and acrosomal status were evaluated simultaneously at 1, 3 and 6 h post-thaw using a triple fluorescent staining procedure and flow cytometry. The best post-thaw survival and thermoresistance of spermatozoa was obtained when Equex was present in the extender (P<0.0001); the semen dilution was performed in 2 steps instead of 1 (P<0.0001); the freezing was carried out using the box instead of the tank (P<0.05); and the straws were thawed at 70 degrees C for 8 sec instead of at 37 degrees C for 15 sec (P<0.0001).

Effects of spermatozoal concentration and post-thaw dilution rate on survival after thawing of dog spermatozoa

The objectives of this study were to evaluate the effects and interactions of freezing dog semen using 4 different sperm concentrations (50 x 10(6), 100 x 10(6), 200 x 10(6) and 400 x 10(6) spermatozoa/mL) in 0.5-mL straws and diluting the thawed semen at 4 different rates (1:0, 1:1, 1:2 and 1:4) on post-thaw survival and longevity of dog spermatozoa during incubation at 38 degrees C. Fifteen ejaculates were collected from 12 dogs and pooled. The semen pool was divided into 4 aliquots containing respectively 4,200 x 10(6), 2,100 x 10(6), 1,050 x 10(6) and 525 x 10(6) spermatozoa, which were centrifuged. Sperm pellets were rediluted with TRIS-glucose-egg yolk extender containing 5% glycerol and 0.5% of Equex STM Paste to obtain the designated sperm concentrations. The semen was frozen in 0.5-mL straws 4 cm above liquid nitrogen (LN2). The straws were thawed at 70 degrees C for 8 sec and the contents of each straw were divided into 4 aliquots and diluted with TRIS buffer at 38 degrees C at rates of 1:0, 1:1, 1:2 and 1:4 (semen:buffer), respectively, making a total of 16 treatments. Sperm motility was subjectively evaluated after thawing and at 1-h intervals during 8 h of incubation at 38 degrees C. Plasma membrane integrity and acrosomal status were evaluated at 1, 3, 6, 12 and 18 h post-thaw using a triple-staining procedure and flow cytometry. For data pooled across the post-thaw dilution rate, motility was higher (P< 0.001) in samples frozen with 200 x 10(6) spermatozoa/mu. The integrity of sperm plasma membranes after 18 h incubation was higher (P<0.05) in samples frozen with 200 x 10(6) and 400 x 10(6) spermatozoa/mL. For data pooled across sperm concentration, samples diluted at a rate of 1:2 or 1:4 had better (P<0.001) motilities after 8 h of incubation than undiluted samples or those diluted at 1:1. The integrity of the sperm plasma membranes was higher (P<0.001) at increasing dilution rates. When the 16 treatments were compared, the best longevity was obtained when semen packaged at a concentration of 200 x 10(6) spermatozoa/mL was diluted immediately after thawing at 1:4 dilution rate.

Intrauterine and intravaginal insemination with frozen canine semen using an extender consisting of orvus ES paste-supplemented egg yolk tris-fructose citrate

Our previous report indicated that addition of Orvus ES Paste (OEP) to the extender of frozen canine semen protected acrosomes and maintained sperm motility after thawing. In this study, artificial insemination (AI) using the frozen semen was carried out. The frozen semen was prepared using egg yolk Tris-fructose citrate, and the final concentrations of glycerol and OEP were 7% (v/v) and 0.75% (v/v), respectively. AI was performed during the optimal mating period predicted from the peripheral plasma progesterone level. In intrauterine insemination (IUI), the bitches were laparotomized and 1 x 10(8) spermatozoa were infused into one of the uterine horns. In insemination of non-OEP supplemented semen, 3 x 10(8) spermatozoa were inseminated. In intravaginal insemination (IVI), 10-40 x 10(8) spermatozoa were inseminated. Conception was obtained in nine of 10 bitches (90.0%) that underwent IUI. The number of newborns was from 1 to 7 (mean 3.6 +/- 0.9). The mean ratio of the number of puppies to the number of ovulations in the inseminated uterine horn was 71.8%. The number of puppies did not exceed the number of ovulation in the inseminated uterine horn. Conception using non-OEP supplemented frozen semen was unsuccessful in all four bitches. In IVI, conception was not obtained in any of the six bitches that received insemination of 10 x 10(8) or 40 x 10(8) spermatozoa, but two of three bitches that received insemination of 20 x 10(8) spermatozoa were fertilized. It was shown that a high conception rate can be obtained by IUI using OEP-supplemented frozen canine semen. Developmenmt of a non-surgical method of IUI and a method of freezing canine sperm applicable to IVI is necessary.

Effects of orvus ES paste on canine spermatozoal longevity after freezing and thawing

Because of weak resistance of canine sperm to freezing, an applicable method of preparing canine frozen semen has not yet been established. We added various concentrations of Orvus ES Paste (OEP) to egg yolk Tris-fructose citrate, and investigated its effectiveness on survival of spermatozoa. Addition of 0.5-1.0% OEP to the extender for freezing canine semen was effective in prolonging post-thaw survival of spermatozoa.

In vitro capacitation of fresh, chilled and frozen-thawed dog spermatozoa assessed by the chloretetracycline assay and changes in motility patterns

The effect of preservation on capacitation status of dog spermatozoa was investigated. Split ejaculates from six dogs were assessed as fresh, chilled for 24 h and rewarmed, and frozen-thawed samples. Capacitation-like status was assessed using the chlortetracycline (CTC)-assay and the measurement of sperm motility patterns using a computer-assisted sperm analyzer. Evaluations were performed on washed spermatozoa immediately after dilution in a Tris-fructose-citrate buffer (TFC) or in canine capacitation medium (CCM), and at 2-h intervals during 8 h of incubation in 5% CO2 in air, at 37 degrees C. Preservation decreased significantly the proportion of uncapacitated spermatozoa. In TFC, at hour 0, chilled-rewarmed and frozen-thawed samples had a significantly lower proportion of uncapacitated, viable spermatozoa than the fresh samples (P<0.05) according to the CTC-assay. The time course of capacitation was accelerated in the preserved samples, compared to the fresh ones. During incubation in CCM, the mean time from hour 0 to when, according to the CTC-assay, the highest proportion of capacitated spermatozoawas present in the samples (time-to-peak), was 4 h for fresh and 2 h for chilled-rewarmed and frozen-thawed samples (P<0.1). The highest values for curvilinear line velocity (VCL) and lateral head displacement (LHD), thought to be descriptive of sperm hyperactivation, were also observed 4 and 2 h after incubation began, in the fresh and the preserved samples, respectively. The difference in time-to-peak for VCL and LHD between fresh, chilled-rewarmed and frozen-thawed semen samples was statistically significant (P<0.02). It can be concluded that based on the CTC-assay and the analysis of motility patterns, capacitation-like changes in dog semen seem to be both initiated and accelerated by the preservation procedures.

Post-thaw evaluation of dog spermatozoa using new triple fluorescent staining and flow cytometry

A new triple fluorescent staining method was developed to evaluate frozen-thawed dog spermatozoa. This method was used to compare functional parameters of canine spermatozoa cryopreserved using 2 different freezing-thawing protocols. One ejaculate from each of 10 dogs was split into 2 aliquots and processed using the Andersen method or the CLONE method. Semen samples were evaluated immediately after thawing and after 3 h of incubation at 37 degrees C. Plasma membrane integrity and acrosomal status of the spermatozoa were evaluated simultaneously by flow cytometry using a combination of 3 fluorescent dyes: Carboxy-SNARF-1 (SNARF), to identify the live spermatozoa; propidium iodide (PI), which only stains dead cells or cells with damaged membranes; and fluorescein isothiocyanate (FITC)-conjugated Pisum sativum agglutinin (PSA), which binds to the acrosomal content of spermatozoa with damaged plasma and outer acrosomal membranes. The accuracy of this new staining method in quantifying the proportions of live and dead spermatozoa by flow cytometry was evaluated by comparing it with the staining technique using carboxyfluorescein diacetate and propidium iodide (CFDA-PI), which yielded high correlation coefficients. The triple-stained sperm samples were also analyzed by epifluorescence microscopy, and both methods proved to be highly correlated. Post-thaw progressive motility and plasma membrane integrity were similar for the 2 freezing procedures, but the proportion of damaged acrosomes after thawing was lower using the Andersen method and the spermatozoa had a higher thermoresistance. This new triple staining method for assessing canine sperm viability and acrosomal integrity provides an efficient procedure for evaluating frozen-thawed dog semen samples either by flow cytometry or fluorescence microscopy.

Comparison of fertility data from vaginal vs intrauterine insemination of frozen-thawed dog semen: a retrospective study

Fertility data from 327 artificial inseminations (AIs) using frozen-thawed dog semen are presented here. The AIs were performed in 274 bitches using semen from 185 males of 76 breeds. The data cover all AIs conducted during 1983 through 1995 at Cryogenetic Laboratories (CLONE) in the United States with AKC-registered and research bitches, and all AIs carried out at the Department of Obstetrics and Gynecology at the Swedish University of Agricultural Sciences in Uppsala, Sweden, using semen frozen by CLONE, in 0.5-mL straws. Semen was frozen using a standardized, three-step liquid nitrogen vapor freezing method. Whelping rates > 70% were obtained when post-thaw motility was 40% or higher. The inseminations were made either directly into the uterus using transcervical catheterization with the Norwegian catheter (NIU; 167 AIs) or a fiberoptic endoscope (EIU; 19 AIs), or in the cranial vagina (VAG; 141 AIs). Resulting whelping rates were 84.4% (NIU), 58.9% (VAG; P < 0.001), and 57.9% (EIU). Increasing the number of VAG AIs per cycle from 1 to 2 enhanced the whelping rate (P < 0.05). The mean interval from the first AI to whelping was 61.8 +/- 2.4 d, and was longer for VAG AIs (62.7 +/- 2.7 d) than for NIU AIs (61.2 +/- 2.1 d; P < 0.001). The mean interval from the last AI was 60.1 +/- 1.9 d, and did not differ between VAG AIs (60.2 +/- 2.2 d) and NIU AIs (60.0 +/- 1.6 d). Gestation length was not influenced by breed or litter size. A total of 1158 pups resulted from the 327 AIs. Litter size was 5.4 +/- 3.0 (NIU), 4.0 +/- 2.7 (VAG; P < 0.001), and 6.0 +/- 2.1 (EIU). Litter size was also influenced by breed (P = 0.006) and, for VAG AIs, by the number of inseminations performed per cycle (P = 0.009). This study is the largest that has been carried out on frozen-thawed dog semen AI. It shows that using a good method for cryopreservation, together with nonsurgical intrauterine AI employing the Norwegian catheter, can yield whelping rates and litter sizes similar to those reported from well-controlled natural matings. Furthermore, this is the first study to show that intrauterine deposition of frozen-thawed dog semen results in a significantly higher whelping rate and larger litter size than vaginal deposition.

Fertility after vaginal or uterine deposition of dog semen frozen in a tris extender with or without Equex STM paste

Twenty-five bitches were artificially inseminated with semen that was frozen-thawed using an egg yolk-Tris-glucose-citrate extender containing 5% glycerol with, or without the addition of 0.5% Equex STM Paste. Semen was collected on 2 occasions from 11 dogs, pooled, and evaluated for sperm motility, morphology and plasma membrane integrity. Each pool was then divided in 2 parts, diluted with 1 of the 2 extenders, and frozen in 0.5-mL straws. In the bitches, plasma progesterone was assayed daily during late proestrus and estrus. Artificial insemination (AI) was performed twice on Days 3 and 5 after the estimated LH peak. For each insemination, 200x10(6) spermatozoa were used. Ten bitches were inseminated with semen frozen without Equex: In 5 females, semen was deposited transcervically into the uterus with the aid of a fiberoptic endoscope and a urethral catheter, while the remaining 5 bitches were inseminated in the cranial vagina using a Norwegian catheter. Fifteen bitches were inseminated with semen frozen-thawed with Equex: Two groups of 5 bitches were inseminated according to the techniques described above, while 5 bitches were inseminated vaginally using the Osiris catheter. Pregnancy was diagnosed and the number of fetuses counted by ultrasound examination. Post-thaw, spermatozoa frozen with Equex tended to have higher total and progressive motility and to survive longer in vitro than when the extender without Equex was used. Spermatozoal concentration, age of the bitches, duration of heat and estrus, and progesterone concentration at LH peak and at the first and second AI did not differ among the 5 groups. The overall pregnancy rate of 84% (21/25) was close to what can be expected from well controlled natural matings. For both freezing extenders tested, 5/5 bitches were pregnant after uterine deposition of semen and 4/5 were pregnant when semen was deposited in the anterior vagina using the Norwegian catheter. With the Osiris catheter, 3/5 inseminations resulted in a pregnancy. No significant differences in pregnancy rate or number of fetuses were found between groups, site of deposition or freezing extender.