Sperm concentration at freezing affects post-thaw quality and fertility of ram semen

We have investigated the effect of sperm concentration in the freezing doses 200, 400, 800, and 1600 × 10(6) mL(-1) on the post-thaw quality and fertility of ram semen. Semen was collected from seven adult Churra rams by artificial vagina during the breeding season. The semen was diluted in an extender (TES-Tris-fructose, 20% egg yolk, and 4% glycerol), to a final concentration of 200, 400, 800, or 1600 × 10(6) mL(-1) and frozen. Doses were analyzed post-thawing for motility (computer-assisted sperm analysis system [CASA]), viability, and acrosomal status (fluorescence probes propidium iodide [PI]/peanut agglutinin conjugated with fluorescein thiocyanate (PNA-FITC), SYBR-14/PI [Invitrogen; Barcelona, Spain] and YO-PRO-1/PI [Invitrogen; Barcelona, Spain]). Total motility and velocity were lower for 1600 × 10(6) mL(-1) doses, while progressive motility and viability were lower both for 800 and 1600 × 10(6) mL(-1). The proportion of viable spermatozoa showing increased membrane permeability (YO-PRO-1+) rose in 800 and 1200 × 10(6) mL(-1). Intrauterine inseminations were performed with the 200, 400, and 800 × 10(6) mL(-1) doses at a fixed sperm number (25 × 10(6) per uterine horn) in synchronized ewes. Fertility (lambing rate) was similar for semen frozen at 200 (57.5%) or 400 × 10(6) mL(-1) (54.4%), whereas it was significantly lower for 800 × 10(6) mL(-1) (45.5%). In conclusion, increasing sperm concentration in cryopreserved semen, at least at 800 × 10(6) mL(-1) and more, adversely affects the postthawing quality and fertility of ram semen.

152 STUDY OF THREE CONSECUTIVE ELECTROEJACULATIONS IN BROWN BEAR (URSUS ARCTOS)

The preservation of threatened species, such as the cantabric brown bear, requires the establishment of genetic resource banks. In these species it is important to increase the efficiency of the electroejaculation techniques so as to collect as many gametes as possible from each collection, and to decrease risks of anesthesia and immobilization. Our objective was to study several characteristics of brown bear semen quality obtained in three consecutive electroejaculations (a, b, and c) in the same anesthetic session. Ejaculates were collected from 11 adult males living in the Cabárceno Nature Park during the breeding season (May–July). Animals were anesthetized by administration of tiletamine + zolazepan (Zoletil 100®) and ketamine (Imalgene 1000®) before being subjected to electroejaculation (6 to 10 V; 250 to 300 mA). From each ejaculate we assessed motility (CASA: SCA, Microptic, Barcelona, Spain), osmolality (mOsm k–1), and viability (VIAB: % viable spermatozoa (spz), SYBR-14 and propidium iodide) and mitochondrial membrane potential (MIT: % spz, JC-1) by flow cytometry. Our results show that total spz (×106 spz) varies widely among individuals depending on the number of electroejaculation. In five males we observe a decreasing pattern (a: 454.50; b: 341.7; c: 138.0); in other two males it is observed an increasing pattern (a: 24.9; b: 70.3; c: 334.3) while in the remaining four males we see a varied pattern, with the sperm production peak in the second electroejaculation (a: 53.4; b: 270.6; c: 107.5). Motility parameters do not show differences among the three electroejaculations, showing a reduction of the progressive motility in the males with increasing pattern with respect to the other patterns. Also, spermatozoa physiology indicators show a relation with the sperm production patterns. For viability (%) it is shown a rising tendency in the increasing pattern (a: 64.0, b: 80.0, c: 79.5) and a reduction tendency in the decreasing pattern (a: 68.7, b: 61.0, c: 58.7). The same is observed in the case of mitochondrial membrane potential (%) (increasing pattern [a: 77.0, b: 89.0, c: 87.0]; decreasing pattern [a: 80.0, b: 76.3, c: 55.7]). Ejaculates of the varied pattern show irregular data for these parameters. On the other hand, osmolality changes depending on the number of electroejaculation (increasing pattern [a: 324.0, b: 289.0, c: 298.3]; decreasing pattern [a: 333.0, b: 297.0, c: 283.0]; varied pattern [a: 264.0, b: 294.6, c: 318.54]) which would determine a change in the spz microenvironment that regulates their physiological activity. Although the high individual variability observed does not lead to solid conclusions, our results indicate that consecutive electroejaculations can be useful for increasing the technique yield in brown bear. Supported by CICYT (CGL2007-63788/BOS) and Cantur SA. 3Supported by Juan de la Cierva program (MICINN, Spain).

Improvement strategies in ovine artificial insemination

Artificial insemination in ram is scarcely widespread comparing with other domestic species. This has been due not only to fertility results being irregular and low but also because of the difficulty in the application of enhancements such as the use of frozen-thawed sperm. Although there is a lot of information on the use of different options to improve these AI results (such as transcervical application, the use of thawed sperm, etc.) commercial programmes can be classified on two general categories: those using refrigerated semen (15 degrees C) by superficial intracervical deposition (vaginal), and, more restricted, those using thawed sperm by intrauterine deposition (laparoscopy). In the present work, we have summarized our viewpoint on three general research lines for the improvement of AI results in sheep: semen preservation, AI procedures and semen assessment. Briefly, in ram it is necessary to develop a medium term methodology of sperm refrigeration (3-5 days), which would allow the distribution of sperm doses to a widespread area. Nevertheless, it is also necessary to develop an intrauterine transcervical AI technique, which allows thawed semen to be applied by vaginal insemination. Besides, the low predictive value of classic assessment techniques limits the ability to adjust the number of spermatozoa per dose according to its actual fertility.

245 USE OF A TRIPLE STAIN (SYBR-14/PI/MC540) FOR VIABILITY AND CAPACITATION ASSESSMENT IN THAWED SEMEN FROM BROWN BEAR (URSUS ARCTOS)

Application of new sperm assessment techniques would improve our capability to determine the effects of cryopreservation on sperm function. This becomes relevant when germplasm banks are established for endangered species, as in the case of the brown bear in Spain. Different triple stain techniques have been used in conjunction with flow cytometry to assess various sperm attributes including viability and acrosome status. However, fluorochromes with similar emission spectra may interfere with data resolution, making acquisition and interpretation of data difficult. The double stain combination of SYBR-14 and PI (propidium iodide; max λ 617) has been widely used to differentiate live from dead spermatozoa (spz), and, more recently, merocyanine 540 (MC; max λ 555) has been used to detect a sperm membrane lipid disorder associated with sperm capacitation. In the present study, we analyzed the suitability of combining SYBR-14/PI with MC for simultaneous determination of the viability and capacitation status of frozen–thawed spermatozoa of brown bears (n = 10; semi-free ranging; Cabarceno Park, Cantabria, Spain) obtained by electroejaculation under general anesthesia (7 mg kg-1 tiletamine + zolazepan and 2 mg kg-1 ketamine). Semen was diluted (Tes-Tris-fructose, 8% glycerol, 20% egg yolk, EDTA, and Equex paste), loaded in 0.25-mL straws, and frozen in a biofreezer at 20�C min-1 to -100�C. After storage in liquid nitrogen, samples were thawed at 65�C for 6 s, divided into 2 aliquots (1–2 million spz mL-1), extended with 300 �L PBS, and stained with SYBR14 (1.2 �L) and PI (3 �L; LIVE/DEAD� Sperm Viability Kit; Molecular Probes, Inc., Eugene, OR, USA). To evaluate the possible interaction of MC on sperm viability, half of the aliquots were counterstained with 1.5 �L of MC (diluted with 2.7 �M of DMSO); the other half were not counterstained (control). All tubes were incubated at 37�C for 30 min, and assessed by flow cytometry (FACSCalibur; BD Biosciences, San Jose, CA, USA). Data were analyzed with Bland-Altman. Results indicated that MC staining was mainly confined to dead spermatozoa (22.2 � 7.7%), whereas a lower percentage of live spermatozoa (5.7 � 1.6%; P < 0.05) were also stained with MC. Possibly, the staining of dead spermatozoa with MC was due to capacitation changes induced by cryopreservation. The percentage of live spermatozoa was not different between samples counterstained with MC (68.9 � 9.2) and non-MC-stained control samples (68.6 � 8.8). Thus, we consider that MC does not influence SYBR14/PI discrimination of viable spermatozoa, and that the 3 stains can be used simultaneously. However, more studies are necessary to determine whether MC can be used to distinguish the capacitation status of brown bear thawed spermatozoa. This work was supported by CANTUR S.A. and CICYT (CGL 2004-0278/BOS).

Influence of breed and age on morphometry and depth of inseminating catheter penetration in the ewe cervix: A postmortem study

A detailed examination of the cervical canal in the ewe was carried out. This analysis could be used to design new catheters for artificial insemination (AI) to achieve deeper cervical penetration and therefore better fertility results. Three hundred and sixty-five cervices from four sheep breeds (Churra, Assaf, Merino, Castellana) obtained postmortem were used. Cervix morphometry and depth of cervical penetration using two types of catheters were determined. A conventional straight catheter for ovine artificial insemination (IMV), and a bent catheter, ending in a stainless steel needle, 9 cm in length and with an 8 mm tip bent 45 degrees , were used. The results showed that the morphometry of the cervix depends on breed and age of the ewe. The cervices of Churra breed were shorter and narrower, and had a higher number of folds than those of other breeds. Postmortem cervical penetration was deeper when the cervices were longer and wider, and with fewer folds (Merino and Castellana breeds). In ageing ewes, the cervix tended to become longer and wider, with loose folds. This decreased structural complexity and significantly improved cervical penetration. The bent catheter allowed significantly greater cervical penetration than the straight IMV one.

Ovum Pick-up in Sheep: a Comparison between Different Aspiration Devices for Optimal Oocyte Retrieval

In vivo ovum pick-up (OPU) in sheep may be improved with a proper choice of aspiration elements (needle and tubing) and aspiration vacuum pressure. In the present study, two experiments were carried out. In Expt 1, visible follicles in ovaries of slaughtered ewes (treated separately according to their diameters: small<3 mm, medium 3-5 mm and large>5 mm) were aspirated using different combinations of the three studied factors such as aspiration flow rate (10, 20, 30, 40 and 50 ml water/min), needle gauge (18 and 20 G) and tubing inner diameter (1, 2 or 3 mm internal diameter). In Expt 2, a study with two 18 G needles of different lengths (18 G: 82 mm; 18 GL: 600 mm) was carried out, using ovaries obtained post-mortem, and performing in vivo laparoscopic follicular aspiration on ewes. We considered good quality oocytes as those with both complete compact cumulus and a homogeneous cytoplasm. Recovery rate, proportion of good quality oocytes (good quality oocytes/100 oocytes recovered) and overall efficiency (good quality oocytes/100 follicles aspirated) were noted. In Expt 1, aspiration flow rate affect remarkable proportion of good quality oocytes (69.5%, 50.5%, 44.8%, 36.5% and 28.3% for flows from 10 to 50 ml/min respectively, p<0.05). Needle gauge did not affect aspiration device efficiency. Thin and intermediate tubings were more effective (overall efficiency rates: 34.9%, 32.3% and 28.1% for 1, 2 and 3 mm respectively, p<0.05). Follicle size did not affect recovery rate, but proportion of good quality oocytes was higher for large (77.9%) and medium (64.4%) follicles (p<0.05). Finally, some combinations of the aspiration device showed greater effectiveness. In Expt 2, needle length did not influence recovery rate, but good quality oocytes rate was significantly modified both post-mortem and in vivo (good quality rate for 18 G vs 18 GL needles: 69.5% vs 47.7% and 58.1% vs 25.4%, post-mortem and in vivo respectively, p<0.05). We conclude that low-aspiration flow rates (10 and 20 ml/min) with thin or intermediate tubings (1 and 2 mm), and any short needle (18 G or 20 G) are the most adequate aspiration factors for OPU in sheep.

223 DESCRIPTION OF GENITALIA AND SPERM RECOVERED POSTMORTEM FROM A PYGMY SPERM WHALE, KOGIA BREVICEPS

A pygmy sperm whale (Kogia breviceps; adult male; 350 kg) was stranded and died on a beach near Cabo Bustos (Asturias, North of Spain) on March 12th, 2005. Finding specimens of this species is a rare event on Spanish shores, although this whale is not considered endangered. Postmortem examination was performed 24 h later. Genitalia (testicles and epididymides) were extracted. The postmortem report indicated that vas deferens and seminal glands seemed to contain an important amount of semen, which was not recovered. Refrigerated genitalia were send to our laboratory, arriving around 40 h postmortem. The refrigerated testicles were in poor physical condition upon arrival, indicating advanced tissue detoriation. The epididymides (very long) were not closely attached to the testicles, but were connected by a loose conjunctive membrane. We divided the epididymides into four regions that approximated the (1) caput, (2) mid-region, (3) corpus, and (4) cauda. Physical characteristics of the genitalia are described in Table 1. The left testicle was larger, and possibly more active, than the right one. A sperm sample was obtained from the cauda region after incising the tissue. Osmolality and pH of the sample were 428 mOsm/kg and 6.62, respectively (maybe due to tissue breakdown) and the sperm concentration was 1194 × 106/mL. Spermatozoa were immotile, even after diluting in buffered medium; it is possible that postmortem damage occurred quickly. However, using flow cytometry we determined that 57% of cauda spermatozoa had intact plasma membranes and acrosomes (determined by staining with 37 mmol/mL propidium iodide and 1 μg/mL PNA-FITC; Sigma, Madrid, Spain). Examination by phase contrast microscopy (×600) showed many spermatozoa with abnormal heads and bent midpieces and flagella, even in the cauda (13% and 21%, respectively). Sperm head morphometry was studied using DiffQuick staining and an automated analysis system (SCA2000; Microptic, Barcelona, Spain). Mean sperm head size was 3.71 ± 0.19 × 2.61 ± 0.12 μm in width and length, respectively. Computer analysis (AnalySiS-GmbH, Cologne, Germany) of phase contrast images revealed that the mean size of the sperm midpiece and flagellum were 3.44 ± 0.19 and 40.95 ± 2.02 μm, respectively. The information obtained after postmortem recovery of the testes and epididymis should be useful to future conservation efforts of the pygmy sperm whale and similar species. The rapid deterioration of the testicular tissue by 40 h postmortem was not expected since good quality sperm samples have been obtained at similar postmortem intervals in other species. Therefore, we recommend that postmortem sperm recovery should be accomplished as rapidly as possible in this species. Table 1. Genitalia measurements

219 MORPHOMETRIC CHARACTERIZATION OF EPIDIDYMAL AND EJACULATED SPERMATOZOA FROM BROWN BEAR (URSUS ARCTOS)

Sperm morphology is an useful characteristic for estimating potential fertility. Currently, we are obtaining baseline information on various aspects of reproduction in the brown bear (Ursus arctos) with the intention of using the knowledge to establish a germplasm bank for the species. In the present report, we describe the results obtained using assisted sperm morphology analysis (ASMA, Sperm Class Analyzer®; Microptic S.L, Barcelona, Spain) to analyze the morphological differences in epidydimal (caput, corpus, and cauda) and ejaculated brown bear spermatozoa. A post-mortem epididymal sperm sample was obtained from an adult brown bear after accidental death. The epididymides were excised, washed, and dissected into the three major segments; caput, corpus and cauda. Then multiple incisions were made in the tissue to allow migration of spermatozoa into the surrounding medium. Semen was collected by electroejaculation from five adult brown bears living in a semi-free ranging environment in the Cabarceno Park (Cantabria, Spain). Anesthesia was induced using tiletamine + zolazepan (Zoletil 100®; Virbac, Carras, France; 7 mg/kg), and ketamine (Imalgene 1000®; Rhone Merieux, Lyon, France; 2 mg/kg). The electroejaculation unit (PT Electronics®; Boring, Oregon) was connected to a 3-lateral electrode transrectal probe (26 mm in diameter, 320 mm in length). Ejaculation occurred at 6–10 V/250–300 mA. For head morphometry assessment, sperm samples were fixed in glutaraldehyde and slides were smeared and air-dried for 2 h. The samples were then stained with Diff-Quik® staining (37°C; 10 min in the red component and 15 min in the blue component). The area, perimeter, length and width, and ellipticity (length/width) of heads were measured from at least 100 spermatozoa/slide. As shown in Table 1, values obtained for each measure were similar in both epididymal and ejaculated spermatozoa. These results provide normal morphometry values for brown bear spermatozoa, a potentially useful characteristic for predicting fertility. Table 1. Head morphometry for epididymis and ejaculated bear sperm (mean ± SD) This work was supported in part by CANTUR S.A. and CICYT (CGL 2004–0278/BOS).

Factors influencing the success of vaginal and laparoscopic artificial insemination in churra ewes: a field assay

Pregnancy rate following artificial insemination (AI) in sheep is variable depending on several factors. The Churra breed (milk breed of the North-West of Spain) yields lower fertility results compared with other local and European breeds (Manchega, Latxa, Merino, Lacaune, Sarde, etc.). In this work we studied the influence of many factors on the fertility of the Churra breed (insemination technique, year, farm, age, male, number of inseminations per ewe, lambing-insemination interval and technician), analyzing lambing data obtained after 44448 inseminations (39.67% cervical AI via vagina, AIV, and 60.33% intrauterine AI using laparoscopy, AIL) in a categorical model. The most important factors influencing fertility after AI were farm, year, season, AI technique, and technician. AIL showed significantly higher fertility results than AIV (44.89% versus 31.25%). Season significantly affected fertility in both cases, but differences were more evident in AIV. Fertility dropped 1.74% (AIV) and 2.07% (AIL) per year as the ewes aged. Finally, AI fertility decreased when the lambing-insemination interval was lower than 10 weeks.

Decay of sperm obtained from epididymes of wild ruminants depending on postmortem time

We have carried out a study on the effect of postmortem time (PT) in some characteristics of epididymal sperm salvaged from hunted Iberian red deer and roe deer. Testis were collected, identified, refrigerated down to 5 degrees C, and sent to our laboratory by the wardens of the hunting reserves. This way, samples were delivered at different times postmortem. Sperm were extracted from the cauda epididymis by means of cuts. Analyzed parameters were: osmolality, pH, motility-both subjectively and with CASA, HOS test reactivity, acrosomal status and viability (assessed with propidium iodide). Osmolality and pH rose with prolonged postmortem time, possibly due to tissue decomposition. Most sperm quality parameters negatively correlated with PT. Besides, when comparing PT classes (groups of 24 h for red deer and 30 h for roe deer), we could appreciate that motility was more affected by PT than other quality variables. Progressive motility was especially impaired. We also classified the samples in high, medium and low quality for each PT group (considering progressive motility, intact acrosomes and reactivity to the HOS test), and it was clear that after 2 days the number of high quality samples was testimonial, and after several days, we almost found only low quality samples. In conclusion, epididymal sperm from Iberian red deer and roe deer undergo a decrease of quality with PT, but it could stay acceptable within many hours postmortem. There are implications for wildlife conservation programs, as epididymal sperm is a good source of germplasm. If valuable animals die and it is not possible to process their sperm immediately, it may still be possible to obtain viable spermatozoa many hours later.

192 PROBLEMS USING JC-1 TO ASSESS MITOCHONDRIAL STATUS IN BROWN BEAR (URSUS ARCTOS) SEMEN

Brown bear is a highly endangered species in Spain and could benefit from biological resource banking. Currently, we are studying several reproductive aspects in order to aquire the knowledge for establishment of a germplasm bank for this species. One of our objectives is to develop adequate protocols for the evaluation of bear sperm before and after cryopreservation. We have used the fluorescent probe JC-1 protocol, which differentially stains mitochondria, according to its activity (Garner DL et al. 1997 Biol. Reprod. 57, 1401–1406). Here we describe one problem that arose using this staining for evaluation of extended bear semen. We electroejaculated 13 adult brown bears (Ursus arctos) (206–311 kg) housed in a half-freedom regime in the Cabarceno Park (Cantabria, Spain). Anesthesia was performed with tiletamine + zolazepan (Zoletil 100®, 7 mg/kg; Virbac, Spain), and ketamine (Imalgene 1000®, 2 mg/kg; Mericl, Sain). We used an electroejaculator (PT Electronics®; Boring, OR, USA) with a 3-electrode transrectal probe (26 mm in diameter, 320 mm long). Ejaculation occurred at 10 V/250 mA. Samples were extended (prepared in our laboratory, Anel L et al. 2003 Theriogenology 60, 1293–1308; M3 modified) and cooled to 5°C for 70 min (pre-freezing protocol). We analyzed individual (MI) and progressive (MP) motility by means of an automated motility analyzer (Hamilton Thorne Biosciences, Inc., Beverly, MA, USA), using a phase contrast microscope (Nikon, ×10). Mitochondrial status was analyzed after diluting the sample 1:100 with buffered medium (20 mM HEPES, 153 mM NaCl, 2.5 mM KOH, 10 mM glucose; Sigma, Madrid, Spain) and adding JC-1 (6.8 μM final; Molecular Probes, The Netherlands). After 30 min at 37°C, 100 cells were counted with an epifluorescence microscope (Nikon, ×400), determining the percentage of sperm with orange-stained (active) mitochondria. We analyzed a total of 55 samples in three different models: fresh, pre-freezing, and thawed. We divided the samples into successful JC-1 staining (valids: V) or failed JC-1 staining (not valid: NV) (depending on the aspect of the stained cells). In not-valid samples we observed a greenish background, with almost no fluorescent spermatozoa. These observations were consistent in a given sample, giving the same V or NV result when we repeated the staining. In fresh and thawed groups there were no NV samples, but in the pre-freezing group there were 40 NV samples (73%). We calculated Pearson correlations (SAS; SAS Institute, Inc., Cary, NC, USA) between percent JC-1 orange population and MI and MP in fresh (r = 0.40 and 0.33; P < 0.001), thawed (r = 0.61 and 0.43; P < 0.001) and pre-freezing samples (r = −0.11 and −0.24; P > 0.05), all respectively. When pre-freezing samples were split between V and NV, the former had good correlations (r = 0.74 and 0.49; P < 0.05), and NV still did not (r = −0.17, −0.27; P > 0.05). We conclude that JC-1 staining is not reliable for the pre-freezing analysis of bear sperm, at least under the conditions described here. This could be due to the interaction of the extender or the refrigeration treatment with the sperm. However, this problem did not occur in the analysis of fresh and thawed samples. Nevertheless, it may be advisable to test other mitochondrial probes for analyzing this kind of samples.

Effect of the interval between estrus onset and artificial insemination on sex ratio and fertility in cattle: a field study

We have carried out a field trial in cattle to study the effect of the interval between the onset of estrus and AI on sex ratio and fertility. Data were obtained from 716 cows that had been inseminated at different times between 8 and 44 h from the visual detection of estrus. Before analyzing the data, it was grouped in three intervals considering the time between estrus onset and AI (8-18, 18-30, and > or = 30 h). Our results show that the percentage of calved females (73.05%) is significantly superior for early inseminations (8-18 h), and it decreases 1.85% per hour from the onset of estrus. Delayed AIs (> or = 30 h) produce a significant deviation of the sex ratio towards the males (72.06%); nevertheless, fertility (percentage of successful pregnancies) diminishes significantly, from 66.19% (8-18 h) to 45.35% (> or = 30 h). In conclusion, variations in the interval between the onset of estrus and AI modify sex ratio. However, we must consider its effect on fertility.

199CHARACTERISTICS OF CHAMOIS (RUPICAPRA PYRENAICA PARVA) EPIDIDYMAL SPERMATOZOA DEPENDING ON TIME POSTMORTEM

The Spanish Cantabrian chamois (Rupicapra pyrenaica parva) is a wild ruminant of the Cantabric Mountains (North of Spain). It is not an endangered species, but it is vulnerable to sarcoptic mange outbreaks and it is appreciated as a hunting trophy. The aim of the present study, as part of a project for establishing genetic resource banks for wild species in the North of Spain, was to determine the effect of postmortem time (PT) on epididymal sperm quality. We obtained 37 sets of testes from males hunted during the breeding season (autumn). The samples, with testes inside of the scrotum to prevent drying, were cooled to 5°C, and processed at 4 different PTs (0–30h, 30–60h, 60–90h, 90–120h). Sperm was obtained from incisions made in the caudal epididymis. Osmolality (OSM) and pH of the undiluted fluid were measured with a cryoscopic osmometer (Osmomat-030, Gonotec TM; Berlin) and an electronic pH-meter (CG 837, SchottTM; Mainz, Germany), respectively. Sperm motility (M) and progressive motility (PM) were assessed subjectively at 37°C. An aliquot of sperm was fixed in glutaraldehyde and used to evaluate acrosome integrity (ACR) and abnormal forms (heads, AH; midpieces, AM; tails, AT). Membrane functionality (MF) was assessed by means of the HOS test (100mOsmkg−1, 18min). All analyses were carried out using a phase-contrast microscope (×100 for motility and ×400 for other analyses). We obtained the Spearman correlation coefficients between the analyzed parameters and PT. Samples were graded on sperm quality parameters (PM, ACR and MF: &gt;60%, high; 60–30%, medium;&lt;30%, low), and their distribution among PT groups was compared (χ2, P&lt;0.05). The following parameters correlated significantly with PT (r and P are shown): pH (0.37, 0.008), OSM (0.52, &lt;0.001), M (−0.51, &lt;0.001), PM (−0.62, &lt;0.001), MF (−0.44, 0.001), ACR (−0.33, 0.02), AT (0.41, 0.005). The correlations of pH and osmolality indicate changes in epididymal fluid composition which could impair sperm viability. In fact, sperm motility, acrosome integrity and membrane functionality showed negative correlations. Also, AT increased with PT, which could be related to membrane damage (along with MF decrease). The distribution of the samples in quality groups is shown in the Table 1. There were no low quality samples in the 0–30h group, but the proportion of such samples increased significantly with PT. In conclusion, epididymal sperm characteristics changed with PT, showing a remarkable loss of quality after the first 30h. Even so, it was still possible to find samples of acceptable quality after several days. This is an important observation when collecting samples for genome resource banking. However, it will be necessary to assess the fertilizing ability of sperm stored for extended periods postmortem to confirm the utility of these findings. Table 1 Variation of sperm quality (PM,ACR and MF: &gt;60, high; 60%–30%, medium; &lt;30%, low) with PT

Effect of epididymis handling conditions on the quality of ram spermatozoa recovered post-mortem

Post-mortem spermatozoa recovery is an important technique for obtaining germplasm reserves from genetically valuable animals or endangered species. However, there are many factors that influence the outcome of this technique. We have studied the effect of the interval between animal's death and sperm recovery (0, 24 or 48 h) on the quality and freezability of ram spermatozoa from cauda epididymidis. Storage temperature of epididymis (room temperature or 5 degrees C) was also analysed. Spermatozoa were diluted with Tes-Tris-Fructose solution supplemented with egg yolk (10%) and glycerol (4%), and frozen using a programmable biofreezer (-20 degrees C/min). Pre-freeze and post-thaw sperm samples showed viable spermatozoa up to 48 h after the animal's death, although their quality declined significantly as post-mortem storage time increased. Epididymis sperm stored at 5 degrees C showed better motility and a lower percentage of abnormal forms than epididymis stored at room temperature after 24 and 48 h. The fertilizing ability of cauda epididymis ram spermatozoa obtained at 0 and 24h after the animal's death is similar to that of ejaculated spermatozoa. Therefore, a good protocol for post-mortem semen collection in rams when epididymal spermatozoa cannot be collected immediately, is to preserve the epididymis at 5 degrees C and process the samples in the first 24h after the animal's death.

Field and in vitro assay of three methods for freezing ram semen

Glycerol has been the most widely used cryopreservation agent for spermatozoa and a wide range of factors affect its action on sperm viability and fertilizing capacity. We tested three methods for freezing ram semen packed in 0.25 ml straws (final cellular concentration: 100 x 10(6) spz/ml). Method M1: Two-thirds of the final volume of diluent was added as solution A (without glycerol) to the pure semen at 35 degrees C. The sample was cooled to 5 degrees C (-0.30 degrees C/min), one-third of final diluent volume was added as solution B (final concentration of glycerol 4%) and the sample was maintained at 5 degrees C for 2h. It was then frozen in a programmable biofreezer (-20 degrees C/min down to -100 degrees C). Method M2: The sample was diluted with a specific solution at 35 degrees C (final concentration of glycerol 3%), cooled to 5 degrees C (-0.20 degrees C/min) and left for 2h. After that, it was frozen in nitrogen vapours. Method M3: Semen was diluted 1:1 in a specific solution (concentration of glycerol 2%) and cooled to 5 degrees C (-0.25 degrees C/min). The sample was then diluted again in the same solution to the final cellular concentration (final concentration of glycerol 4%). It was left for 1h at 5 degrees C and then frozen in a programmable biofreezer (-20 degrees C/min down to -100 degrees C). Best total motility (TM) and progressive motility (PM) (75.8 and 55.18%) were obtained using Method M3. Methods M1 and M3 gave significantly higher values (P<0.05) for kinetic parameters: average path velocity (VAP) (81.3 and 85.2 microm/s), straight-line velocity (VSL) (72.8 and 77.3 microm/s) and linearity (LIN) (66.6 and 68.8%). Method M2 showed the lowest kinetic parameters of motility (VAP 74.4, VSL 67.3 and LIN 62.5) and the highest percentage of cells with damaged plasma membrane (53.8%). Method M1 gave the worst results in viability and acrosome status assessed using fluorescence probes (31.3%-dead cells with damaged acrosomes-versus 25.4% in M2 and 23.3% in M3). A field trial carried out on fertility showed a significantly higher percentage of pregnant or lambing ewes (P<0.05) with Method M3 (67.3% versus 51.1% for M1 and 58.8% for M2). We concluded that the use of a simple dilution medium (test-fructose-glycerol-egg yolk) with the addition of glycerol (to 2% at 35 degrees C and to 4% at 5 degrees C) in two steps together with a programmable biofreezer was a productive method for freezing ram semen.

Ultrastructural and cytochemical comparison between calf and cow oocytes

The use of prepubertal females (calves) to obtain oocytes for in vitro fertilization (IVF) programs, is being analyzed currently. This will increase the availability of female oocytes and will allow a reduction of the interval between generations. Differentials in the development capability of calf and cow oocytes have been assessed by different authors, establishing several ultrastructural and metabolic differences between them. This paper analyzes the morphometric and cytochemical differences between calf and cow oocytes through microscopic techniques. The oocytes morphologically classified as good are processed for electron microscopy a) in Epon 812 epoxy resin for morphometric analysis or b) in low temperature Lowycril K4M resin for cytochemical evaluation using Con A, GS, LPA, UEA, and WGA lectins marked with colloidal gold as probes. Calf oocytes show a greater density of microvilli on their surface and a greater number of endocytosic vesicles than those of the cow. On the other hand, cow oocytes show a larger superior mitochondrial population. In the cumulus cells it can be seen that calf oocytes have a greater volume of lipid droplets. Cytochemical analysis shows that calf oocytes have lectin marking restricted to the plasmic membrane, highlighting the presence of LPA. In cow oocytes, lectin marking can be seen both on the plasmic membrane and in the vacuoles, in both cases, with the LPA highlighted. In the zona pellucida of calf and cow oocytes, the same sugars appear (GS, LPA, WGA), and marking with LPA is more extensive in cow oocytes.

The hypoosmotic swelling test performed with coulter counter: a method to assay functional integrity of sperm membrane in rainbow trout

The hypoosmotic swelling test (HOS) is one of the methods used to evaluate sperm quality in mammals. This test is based on the swelling ability that functional spermatozoa have when submitted to hypoosmotic solutions. Only a slight increase in size is caused in rainbow trout spermatozoa in such conditions and it is not possible to distinguish between reactive cells (cells who were capable to increase in volume) and non-reactive cells (did not increase in volume) under light microscopy. In our approach we have used the coulter counter to verify the effectiveness of the HOS test in this species. Semen was diluted in different hypoosmotic solutions (50, 100, 150, 200, 250 and 320 mosM/kg) and cell volume measured at different times after dilution (30 s, 2, 5, 10, 20, and 30 min). The higher percentage of reactive cells was achieved with the 100 mosM/kg solution and swelling occurred before 30 s. Even with this solution, the small increase in cell size caused the overlapping of volumes from swollen and non-swollen spermatozoa. In order to analyse the data and to choose a parameter suitable for assessing cell reactivity, the test was performed in samples containing known rates of live/dead cells. Two parameters were analysed after swelling: the increase in volume and the percentage of cells over a standard volume (reactive cells). Results showed a high correlation between the percentages of reactive cells and the known rate of live cells (r2 = 0.65). This fact suggests that HOS test could be used to analyse the integrity and functionality of rainbow trout fresh sperm. To study the reliability of this test in cryopreserved sperm, simple linear regressions were made between cell viability determined by Hoechst 33285 dye and the two parameters obtained from coulter counter data. No significant correlation was observed in either case, showing that structural and functional integrity do not correlate after freeze/thaw. Consistently, the HOS test is not a reliable method to evaluate cryopreserved sperm quality in rainbow trout.