Electroejaculation in chimpanzees and gorillas and artificial insemination in chimpanzees

Electroejaculation was performed in 3 chimpanzees, 1 pygmy chimpanzee, and 2 gorillas with an instrument that delivers a modified sine wave current with a frequency of 24 Hz. The current stimuli were applied by a rectal probe with longitudinal electrodes. The electrical parameters varied from 6 to 12 V and from 30 to 40 mA for response of erection and lay between 8 and 18 V and between 40 and 145 mA during semen emission. Eleven chimpanzee semen samples showed the following data (x ± SD): total volume 1.9 ± 1.3 ml, volume of the liquid fraction 0.3 ± 0.2 ml, spermatozoa per ejaculate 743 ± 376 × 10⁶, sperm motility 52.7 ± 9.6%, morphologically abnormal spermatozoa 12.2 ± 7.5%. From an adult gorilla, three semen samples were collected, in each case without spermatozoa. The electrostimulation of a 6-year-old gorilla led to an erection, but not to semen emission. Three female chimpanzees were inseminated with fresh or frozen semen, each of them within three different estrous cycles. None of these inseminations led to a pregnancy.     

Seasonal variation in the semen characteristics of Muturu (Bos brachyceros) bulls

Semen was collected by electroejaculation from seven mature Muturu bulls at weekly intervals for 9 weeks in each of three seasons (‘Dry’, ‘Rainy’, and ‘Late Rainy/Early Dry’) to study the effect of season on semen characteristics. The respective mean values for the ‘Dry’, ‘Rainy’ and ‘Late Rainy/Early Dry’ seasons were: volume 1.8 ± 0.1, 2.3 ± 0.1 and 2.0 ± 0.1 ml; percentage motility 36.2 ± 2.6, 37.7 ± 2.8 and 27.5±2.9; and percent morphologically normal sperm 70.0 ± 3.1, 79.1 ± 2.6 and 79.8 ± 2.3. No seasonal differences were found for sperm concentration/ml (overall mean 1.92 ± 0.16 × 10⁸) and for sperm output/ejaculate (overall mean 4.14 ± 0.39 × 10⁸). The chemical composition of seminal plasma (mg %) for the respective seasons was calcium: 4.8 ± 1.0, 7.9 ± 0.9 and 2.5 ± 0.7; magnesium: 4.8 ± 0.4, 4.3 ± 0.7 and 2.5 ± 0.7; and chloride: 330.7 ± 33.7, 136.0 ± 9.6 and 344.3 ± 31.8. No seasonal differences were found in sodium or potassium concentrations. Fructose was found in the semen of only one bull and only during the ‘Dry’ season.     

Use of two anesthetic combinations for semen collection by electroejaculation from captive coatis (Nasua nasua)

The objective was to compare the effects of ketamine-xylazine or tiletamine-zolazepam combinations as anesthetic protocols for captive coatis (Nasua nasua) for semen collection by electroejaculation. Five mature male coatis were physically restrained and then anesthetized by im injections of ketamine (10 mg/kg) plus xylazine (1 mg/kg) or a tiletamine-zolazepam combination (8 mg/kg). For the two combinations, additional quarter-doses of ketamine or the tiletamine-zolazepam combination were administered when necessary. Semen was collected by electroejaculation and immediately evaluated for color, volume, pH, sperm motility, vigor, morphology, acrosomal integrity, and percentage of live cells. Overall, collection of nine ejaculates was attempted from five animals for each treatment. Regardless of the anesthetic combination, all animals developed an erection during each attempt to collect semen. Ejaculates were obtained in all (9 of 9) attempts that used ketamine-xylazine for anesthesia, but in only 3 of 9 attempts (P < 0.05) when tiletamine-zolazepam was used. All ejaculates contained sperm, with no significant differences in semen characteristics between the two anesthetic combinations. Recovery was smooth in all animals. In conclusion, semen collection by electroejaculation in coatis was significantly more successful with the use of a ketamine-xylazine combination than with tiletamine-zolazepam.     

Semen characteristics of the swamp buffalo (Bubalus bubalis)

The semen characteristics were studied in 182 ejaculates collected with a bovine artificial vagina from five swamp buffalo (Bubalus bubalis) bulls. The mean values were: volume, 2.9 ml; general motility, 70.7%; live (unstained) sperm, 86.5%; abnormal sperm, 10.3%; intact acrosomes, 82.4%; sperm concentration, 1.06 × 10⁹cells/ml and total sperm/ejaculate, 3.18 × 10⁹cells/ml. Among the sperm abnormalities noted were “knobbed” acrosome, abaxial implantation, the “Dag” defect and the corkscrew midpiece. There were no significant (P > 0.05) monthly variations for any of the semen characteristics studied.     

Semen characteristics of the quaker parakeet (Myiopsitta monachus)

This report describes characteristics of semen samples collected from eight captive quaker parakeets (Myiopsitta monachus) using the massage technique. Overall, semen characteristics were (mean±SE, range in parentheses, n=8 males): ejaculate volume 1.96±0.26μl (1.02–2.96), sperm concentration 346.6±64.6 million/ml (74.8–579.3), and number of sperm per ejaculate 0.71±0.16 million (0.09–1.53). Significant differences were observed between males for all three semen characteristics. Semen pH for the eight males ranged from 8.05 to 8.5. The semen samples were collected early in the breeding season, so the data reported may not be representative of ejaculates from males in peak breeding condition. However, this study provides the first rigorous semen data from this species and demonstrates that good‐quality semen samples, suitable for artificial insemination, can be collected regularly from quaker parakeets using the massage technique. Zoo Biol 21:507–512, 2002. © 2002 Wiley‐Liss, Inc.     

Semen evaluation of giant pandas (Ailuropoda melanoleuca) at the Wolong Reserve

Semen from 4 wild-caught giant pandas (Ailuropoda melanoleuca) held at the China Conservation and Research Centre for the Giant Panda was collected (22 samples during 1991–1993) by electroejaculation, and evaluated for use in artificial insemination. Semen characteristics (mean ± SD) recorded were as follows: semen volume–1.5 ± .9 ml (range—0.3–3.5); sperm density 1.5 ± 0.1 × 10⁹/ml (range—0.24–4.2); motility 79 ± 10% (range—60–95); abnormal sperm 14 ± 5% (range—10–27); and pH 7.1 ± 0.2 (range—6.7–7.5). There were significant differences from year to year (P < 0.05) in semen volume collected and in the percentage abnormal sperm in 1993 compared to other years. There were no significant differences among semen produced from the four different pandas. Data collected were similar to reports for other giant pandas, and semen from all 4 giant pandas was considered suitable for use in artificial insemination. © 1994 Wiley-Liss, Inc.     

Noninvasive semen collection from an adult orangutan

Preservation of the genetic diversity of the captive orangutan, especially the wild-caught founders, is critical in maintaining a long-term population in zoological parks. One solution to the problem of maintaining maximum genetic diversity would be to initiate a program of artificial insemination for genetically underrepresented individuals through the banking and interinstitutional use of cryopreserved semen. However, little is known about basic orangutan semen characteristics, and current methodology is inadequate to support such a program. In this paper, we report the results of semen collection from an adult Sumatran orangutan (Pongo pygmaeus abelli), using an artificial vagina without anesthesia or electrical stimulation. A total of 27 ejaculates were evaluated during a 1-year period. The total and liquid volumes of the ejaculates at 1 h following collection were 6.1 ± 0.6 ml and 2.6 ± 0.4 ml, respectively (mean ± SEM). The liquid portion continued to exude semen for 2 h; however, 90% of the motile sperm was exuded within the first 30 min. The total number of sperm in the ejaculate was 164 ± 10⁶ ± 16.5, and the percentage of motile cells was 60 ± 2.7%. We conclude that the artificial vagina provides a promising technique for semen collection in the orangutan, and view these results as an initial step in developing methods for in vitro sperm capacitation, sperm cryopreservation, and artificial insemination. © 1993 Wiley-Liss, Inc.     

Sperm loss using different artificial vaginas in rams

The objective of the present study was to evaluate the effect of certain factors on sperm loss during ram semen collection, using an artificial vagina (AV). The factors analyzed were the effect of the male (8 rams), length of the artificial vagina (short versus long), order of the ejaculate (first versus second ejaculate) and lubrication technique (with or without lube). An observational study from a data set containing 55 semen collections from the 8 rams of different breeds (Montadale, Suffolk, Hamphshire, Polypay) were evaluated during the breeding season using a multiple regression statistical analysis over a period of 10 weeks. The results did not show any differences between rams, order of the ejaculate or the use of lubrication on sperm loss. The two types of artificial vaginas however showed significant differences in the percentage sperm loss (P < 0.001). The total ejaculate volume (collection tube volume + liner and cone recovery volume) and sperm concentration/ml (×10⁹) were similar when using the two types of artificial vaginas. The total ejaculate volume recorded for the short artificial vagina was 1.5 ± 0.4 ml and for the long artificial vagina was 1.3 ± 0.6 ml. The concentration of the ejaculate was 2.7 ± 0.6 × 10⁹ sperm/ml for the short artificial vagina and 2.9 ± 0.7 × 10⁹ sperm/ml for the long artificial vagina. The volume of semen in the collection tube using the short artificial vagina was 1.3 ± 0.4 ml, compared to the 0.7 ± 0.5 ml for the long artificial vagina (P < 0.001). The percentage of sperm loss from the short artificial vagina (12.9 ± 5.9%) was significantly lower than when using the long artificial vagina (50.8 ± 13.9%; P < 0.001). From this study, it may be concluded that the type of artificial vagina affects the sperm loss; with the shorter AV recording a lower sperm loss. No effects were detected between rams, order of the ejaculate or the use of lubrication on sperm loss. From the results obtained the use of the short artificial vagina can be recommended.     

Sperm motility and seminal fluid composition in the burbot, Lota lota

Sperm motility and composition of the seminal fluid in Lota lota were investigated. Fives after motility initiation, 88.2 ± 12.4% of the spermatozoa were motile, their mean average path swimming velocity was 61.6 ± 16.3 μm s^?1 and their principal swimming type the linear motion (77.4 ± 20.9%). In distilled water the rate of motile spermatozoa decreased to 0% in 40s. In 25–50 mosmol kg^?1 electrolyte (NaCl) or non-electrolyte (glucose, sucrose) solutions, motility was prolonged for 10s and these solutions can therefore increase the efficiency of artificial fertilization when used for sperm motility activation. When semen was diluted in electrolyte or non-electrolyte solutions with osmolalities higher than 50 mosmol kg^?1, sperm motility rates and swimming velocities decreased, and at osmolalities of 400 mosmol kg^?1 motility was completely suppressed. In the seminal fluid with an osmolality of 290.08 ± 45.22 mosmol kg^?1, sodium levels of 139.86 ± 23.79 mmol × 1^?1, potassium levels of 11.59 ± 2.45 mmol × 1^?1 and calcium levels of 0.20 ± 0.08 mmol × 1^?1, sperm motility was inhibited. Under in vitro conditions, artificial saline solutions resembling the seminal plasma composition and 400 mosmol kg^?1 NaCl or glucose solutions were useful as motility inhibiting solutions for predilution of semen. Sperm motility was not affected by pH 7.5–9.0, but at pH 6 the motility rate and the swimming velocity were reduced; seminal fluid pH was 8.47 ± 0.02. Therefore buffering of the artificial saline solutions can provide more stabile conditions for semen during storage and activation. Temperature optimum of semen was between 2 and 5°C. At higher temperatures semen became spontaneously motile. Therefore, controlled temperature conditions are an important factor for handling of semen. The qualitative, organical composition of seminal fluid was similar as in other fresh water teleosts.     

Influence of season on characteristics of the ejaculate from bulls in an artificial insemination centre in Nigeria

The influence of season on the ejaculate characteristics of Zebu, Friesian and their crossbred bulls in an A.I. programme in Nigeria was investigated over a 2-year period.Ejaculate volume, sperm concentration, percent morphologically normal spermatozoa and percent live spermatozoa were significantly higher in the rainy season than in the dry season. Total spermatozoa per ejaculate averaged 3.32 × 10⁹ and 10.10 × 10⁹ for the dry and rainy seasons respectively. Corresponding proportions of total morphologically defective spermatozoa per ejaculate were 14.05% and 6.46%. Percent live spermatozoa were 82.34% and 84.61% while the corresponding sperm concentrations were 0.97 × 10⁹ rmand 1.74 × 10⁹ for the dry and rainy seasons respectively. All differences were statistically significant (P < 0.05).Ejaculate quality was better during the rainy season. Consequently semen collected and frozen during the rainy season may produce higher fertility rates in an A.I. programme.     

The effect of optimal and suboptimal concentrations of sperm on the fertility of fresh and frozen bovine semen and a theoretical model to explain the fertility differences

In vitro trials on the survival of sperm stored fresh or rediluted after freezing showed quite significant differences in the total survival time of sperm incubated at 37°C. Even after adjusting for different sperm concentrations, survival was still superior in the fresh compared with rediluted frozen sperm (124 ± 5.5 h vs. 75.8 ± 3.1 h). There was no significant difference in fertility between rediluted frozen sperm (RDF) and fresh sperm, both stored in Caprogen, when the insemination dose was 20 × 10⁶ and 2.5 × 10⁶ sperm, respectively. Reduction of the sperm concentration in the insemination dose from 20 × 10⁶ to 5 × 10⁶ sperm in RDF and from 2.5 × 10⁶ to 0.5 × 10⁶ sperm in fresh semen reduced non return rates by 7.9% and 7% respectively (P < 0.001). The bull × dose rate interaction for non return rate was not significant for fresh semen, but significant for RDF (P < 0.001). Two theoretical models were used to examine the effects of freezing on the survival of sperm in the female reproductive tract and the probability of fertilisation. There is a suggestion that freezing had no effect on survival time of sperm in the female reproductive tract, but either reduced the probability of fertilisation by a single spermatozoon or altered the pattern of sperm survival in the female reproductive tract.     

Effect of dilution rate on feline urethral sperm motility,viability, and DNA integrity

This study was designed to investigate if the characteristics of feline urethral sperm can be affected by high dilution in an artificial medium. The semen collected by urethral catheterization from eight male cats was evaluated for sperm concentration and motility and subsequently diluted with a TRIS-based extender to the concentration of spermatozoa 10 × 10⁶/mL, 5 × 10⁶/mL, and 1 × 10⁶/mL. Immediately after the extension samples were assessed for motility, cell viability using SYBR-14 and propidium iodide, acrosome integrity using lectin from Arachis hypogaea Alexa Fluor 488 Conjugate, and propidium iodide and chromatin status by acridine orange. Compared with 10 × 10⁶/mL dilution rate, spermatozoa diluted to 1 × 10⁶ sperm/mL had a significantly lower proportion of motile (31.1% ± 19.8 and 0.7% ± 1.6, respectively, P < 0.05) and viable spermatozoa (88.3% ± 3.1 and 69.1% ± 12.8, respectively, P < 0.01). There was no dilution-related difference in the acrosome integrity (76.7% ± 11.9 vs. 75.9% ± 10.6) and chromatin status (defragmentation index, 3.3% ± 0.97 vs. 3.4% ± 1.7). These results indicate that feline urethral semen is susceptible to high dilution rate, and some sperm characteristics can be artifactually changed by semen dilution. It also suggests the potential role of seminal plasma in maintaining sperm motility and viability in high dilution rates.     

The influence of the length of time after hormonal treatment with [(d‐Ala6, Pro9 NEt)‐mGnRH+metoclopramide] i.e. Ovopel on barbel Barbus barbus (L.) milt quality and quantity indicators

The study purpose was the analysis of barbel Barbus barbus (L.) milt quality and quantity with regard to the time following stimulation with [(D‐Ala⁶, Pro⁹NEt)‐mGnRH+metoclopramide] i.e. Ovopel. Selected parameters such as total volume of milt (TVM, ml), volume of milt per kg of body weight (VOM, ml kg^?1 b.w.), sperm concentration (×10⁹ ml^?1), total sperm production (TSP, ×10⁹), osmolality (mOsm kg^?1) and pH of seminal plasma were determined. Sperm motility was analyzed by the CASA system, i.e. the percentage of sperm motility (MOT, %) and their progressive motility (PRG, %), curvilinear velocity (VCL, μm s^?1) and straight line velocity (VSL, μm s^?1), amplitude of lateral head displacement (ALH, μm), and beat cross frequency (BCF, Hz). Milt was collected from 12 specimens (N = 12), with the first portion obtained 12 h following treatment with Ovopel (1 granule kg^?1 b. w.). Subsequent portions of milt were taken at 24 h intervals, i.e. after 36, 60, 84, 108, and 132 h. The control group (Control, N = 12) was injected with 0.9% NaCl at 0.5 ml kg^?1b.w. from which milt was taken 12 h post injection. The highest TVM, VOM and TSP values were recorded 12 h after Ovopel treatment (3.2 ± 0.7 ml, 36.7 ± 10.5 ml kg^?1 b.w. and 39.1 ± 9.4 × 10⁹, respectively); lowest values were recorded after 132 h (0.8 ± 0.4 ml, 11.1 ± 6.5 ml kg^?1b.w. and 13.7 ± 7.5 × 10⁹, respectively). The highest seminal plasma osmolality values (300.0 ± 42.6 mOsm kg^?1) as well as the lowest sperm concentration (12.5 ± 1.5 × 10⁹ ml^?1) were observed 12 h after Ovopel treatment. No significant differences in the percentage of sperm motility (MOT) were noted during any of the periods after hormonal stimulation, however, a change in the character of their movement (PRG) was observed. The lack of significant differences (P > 0.05) in VCL and VSL values between 12 h and 60–132 h indicates that the lengthening of time does not lead to a decrease in sperm velocity and, therefore, is not likely to have a negative impact on their quality. The highest ALH (1.9 ± 0.2 μm) and BCF (11.5 ± 1.1 Hz) values were observed when the effect of stimulation was most noticeable, i.e. 12 h after Ovopel treatment. Based on the total milt volume and sperm production, the best time for milt collection from barbel is 12 h post‐hormonal treatment; 84 h post‐hormonal treatment, TVM, VOM, TSP and some CASA parameters decreased, which suggest the same aging process in sperm.     

Sperm quality of Colossoma macropomum after room‐temperature and cold storage

The objective of this study was to evaluate the effects of cold and room‐temperature storage on the quality of Colossoma macropomum sperm. The experiment was carried out in December (end of Spring), in Nova Mutum‐MT, Brazil, involving nine C. macropomum males (4 years old; 6.4 ± 1.5 kg average weight). The fish were selected and transferred to masonry tanks (4 m³) in a laboratory (water renewal rate: 10 L/s; average water temperature: 28°C). Subsequently, reproduction was induced using 2.5 mg of crude carp pituitary extract/kg and the semen was harvested 240 degree hours after hormonal induction. The following sperm characteristics were analyzed every 5 hr using Image J/casa software: total motility (MOT), curvilinear velocity (VCL), average path velocity (VAP), straight‐line velocity (VSL), straightness of sperm path (STR), wobble (WOB), progressive motility (PROG), beat cross frequency (BCF) and total number of spermatozoa (NSPZ). A fresh sample of semen from each animal was kept at room temperature (25.3 ± 1.2°C). For analysis of cooled semen, syringes were kept in cooling boxes at an average temperature of 16.9 ± 2.1°C. The reduction (p < 0.05) of MOT in semen kept at room temperature occurred at 10 hr (13.95%); in cooled semen, however, MOT declined at 15 hr (76.87%). At 15 hr, there was practically no MOT in the semen kept at room temperature (0.20%), whereas in the cooled semen this situation was observed only at 35 hr (2.91%) The MOT of cooled sperm was higher (p < 0.05) at all times (except zero time), compared with the semen maintained at room temperature. At 15 hr, the cooled spermatozoa showed higher (p < 0.05) VCL (142.18 μm/s) and BCF (29.72 Hz) than those maintained at room temperature (VCL: 51.18 μm/s; BCF: 19.57 Hz). After 15 hr, only the cooled sperm showed quality. In conclusion, semen cooling allows for extending the viability of C. macropomum spermatozoa from 5 to 10 hr without compromising their quality in most characteristics. At 15 and 25 hr of cooling, sperm viability is still observed, though with decreased quality.     

First pregnancies in jennies with vitrified donkey semen using a new warming method

Sperm vitrification has been recently developed, but fertility trials have not been performed yet in equine species. In this study, a new warming technique for vitrified donkey semen was developed and the uterine inflammatory response and fertility were compared to conventional freezing. In Experiment 1, sperm was vitrified in straws and warmed in 3 ml of extender or in a water bath at: 37 °C/30 s; 43 °C/10 s; and 60 °C/5 s. Sperm motility, plasma and acrosome membranes and DNA integrity were compared between treatments. In Experiment 2, jennies were inseminated twice (500 × 10⁶ sperm) in the uterine body either with vitrified or frozen semen (2 cycles/jenny). Pregnancy rates and the uterine inflammatory response (polymorphonuclear neutrophil concentration; PMN) were evaluated after artificial insemination (AI). No differences between warming in extender/water bath were found and 43 °C/10 s was better than lower temperatures in terms of total (53.8 ± 13.2%) and progressive sperm motility (41.4 ± 11.4%). No differences in PMN concentration (× 10³ PMN/ml) were found between vitrified (276.8 ± 171.6) or frozen (309.7 ± 250.7) semen after AI. However, PMN decreased faster (P < 0.05) using vitrified semen. Pregnancy rates were greater for vitrified (22%) than frozen semen (10%) but not statistically different. In conclusion, donkey sperm vitrified in straws could be directly warmed in a water bath at 43 °C/10 s, reducing the uterine inflammatory response obtained after AI and promoting positive pregnancy outcomes. These findings confirm the possibility to use vitrified semen as an alternative for AI in jennies.     

Effect of Dietary Selenium and Vitamin E on Ganders’ Response to Semen Collection and Ejaculate Characteristics

Compared to other domestic bird species, geese exhibit the lowest reproductive efficiency (poor semen quality, low egg production, and poor fertility and hatchability rates). From an economic perspective, it is a necessity of improve these reproductive traits. Studies have demonstrated that the essential trace element—selenium—plays key roles in testicular development and the maintenance of spermatogenesis. The aim of the present study was to determine the effect of feed supplementation with organic selenium and vitamin E on ganders’ response to manual semen collection and semen quality. Sixteen 3-year-old White Koluda ganders were randomly divided into two groups. The control group was provided commercial feed while the experimental group was provided with the same commercial feed supplemented with selenium (0.3 mg/kg) and vitamin E (100 mg/kg). The response of individual ganders from both groups to manual semen collection and the quality of the semen collected were evaluated. The supplements increased (P?≤?0.05) the frequency and decreased the time interval of a complete ejaculatory response of the ganders to manual semen collections (82.7 % supplement vs. 73.5 % control). Males from the supplemented group had significantly higher (P?≤?0.01; P?≤?0.05) ejaculate volumes, sperm concentrations, and percentages of viable sperm and lower percentages of immature sperm (spermatids). Lipids peroxidation, expressed in terms of the malondialdehyde concentration, was lower (P?≤?0.01) in semen of the supplemented group (0.172 nmol/50?×?10⁶) as compared to the controls (0.320 nmol/50?×?10⁶). Moreover, the duration of the reproductive period of the ganders in the experimental group was 1 week longer. The results show that supplemental dietary selenium and vitamin E improved both the ganders’ response to manual semen collection and semen quality. We conclude that such feed supplementation could lead to greater economic benefits through increased reproductive efficiency within the goose production industry.     

Morphology, chemical contents and physiology of chondrostean fish sperm: a comparative study between Siberian sturgeon (Acipenser baerii) and sterlet (Acipenser ruthenus)

The present study was carried out with two sturgeon species, Siberian sturgeon (Acipenser baerii) and sterlet (A. ruthenus) to compare spermatological parameters to better understand inter‐species differences. Significant differences between morphometric features were observed such as acrosome length, acrosome width, head length, midpiece width and flagellar length, while midpiece length did not reveal such differences. The sterlet has a shorter spermatozoon than the Siberian sturgeon. Ultrastructural parameters vary significantly in terms of length of the nucleus, diameter of the endonuclear canals (EC), size of posterolateral projections (PP) and diameter of flagellum. Mean values for density of spermatozoa in the semen, seminal plasma pH, osmolality (mOsmol kg^?1), along with Ca²⁺, Na⁺, K⁺, Cl^? ions concentrations (mm ) were determined to be 0.61 ± 0.37 × 10⁹, 8.16 ± 0.18, 77.20 ± 52.28, 0.24 ± 0.06, 31.39 ± 10.21, 3.51 ± 1.10, 14.00 ± 4.30 in A. baerii and 0.41 ± 0.32 × 10⁹, 8.13 ± 0.19, 50.74 ± 6.27, 0.16 ± 0.11, 20.11 ± 3.78, 1.26 ± 0.54, 6.11 ± 0.60 in A. ruthenus, respectively. Significant differences were observed in Na⁺, K⁺ and Cl^? concentrations in the seminal plasma as well as in sperm velocity. The percentage of motile spermatozoa did not show any significant difference between the two species. Comparing the results of this study with published literature data on sturgeon spermatozoa reveals that morphological and ultrastructural parameters of spermatozoa together with some parameters of the seminal fluid and spermatozoa velocity can be used in comparative spermatology to better understand inter‐species differences. The observed biochemical and physiological differences should be also considered for the development of methods for controlled reproduction and for sperm cryopreservation techniques.     

Rhesus monkey sperm penetration into zona-free hamster ova: Comparison of preparation and culture conditions

A major problem in development of nonhuman primate in vitro fertilization is the selection of donor males and repeated collection of consistent sperm samples. In practice, collection of a viable semen sample is highly dependent on operator technique and the type of animal restraint. We report an updated method for semen collection from the rhesus monkey (Macaca mulatta), use of TES-Tris (TEST) Yolk Buffer (TYB) for prolonged sperm storage and improved results of hamster ovum penetration assay. Semen was obtained from adult males restrained with 2.0 mg/kg IM ketamine hydrochloride prior to direct penile stimulation (Grass SD-9, frequency 150, delay 9, duration 7, volts 12–18, repeat mode, twin pulse). Liquified semen was washed and centrifuged twice at 100 × g for 5 min in BWW, Ham's F-10 and TALP and allowed to swim-up 60 min at 37° in 5% CO₂ and air. Alternatively, semen was mixed 1:1 with TYB, refrigerated 20 h at 4°C, centrifuged at 100 × g for 5 min, and the pellet resuspended in 1.0 ml of TALP or BWW prior to use. Hamster ova penetration was achieved with capacitated macaque sperm. Penetration was significantly improved (P < .001) with preincubation in TYB followed by resuspension in TALP (79%).     

Semen collection,characterization, and cryopreservation in a Magellanic penguin (Spheniscus magellanicus)

A cooperative method was developed for collecting semen from a Magellanic penguin. Ejaculate parameters and semen production during a breeding season were characterized. Experiments were performed to study the effect on penguin spermatozoa of two temperatures (4°C and 21°C) for short‐term storage, and two cryoprotectants (dimethylsulfoxide [DMSO] and ethylene glycol [EG]) for long‐term storage (cryopreservation). All dilutions were made using modified Beltsville Poultry Semen Extender. Sperm quality was assessed by evaluating motility and forward progression (sperm motility index [SMI]), viability, and morphology. A total of 39 ejaculates was collected over the 40‐day study period. Thirty‐eight ejaculates contained spermatozoa, but semen quality decreased toward the end of the study period. Varying levels of urate contamination were present in all ejaculates. Sperm quality parameters were similar for diluted samples held at 4°C and 21°C, and samples maintained high numbers of viable (77.8 ± 5.4%) and morphologically normal (67.9 ± 2.5%) spermatozoa at 3 hr. SMI and percentage of viable sperm decreased (P < 0.05) and the number of spermatozoa with a bent head or midpiece increased (P < 0.05) for both temperature groups over the 3‐hr storage interval. DMSO and EG were equally effective in maintaining penguin sperm quality parameters during the cryopreservation and thawing process. Frozen‐thawed semen maintained 69 ± 5 and 78 ± 3% of its pre‐freeze SMI and viability, respectively. SMI and viability decreased slightly during the cooling and equilibration phases but remained relatively stable during the 3‐hr storage interval post‐thaw. Frozen‐thawed semen also exhibited an increase (P < 0.05) in spermatozoa with a bent head or midpiece over time. The pre‐freeze SMI was higher (P < 0.05) for ejaculates with low levels of urates (clean ejaculates) compared with ejaculates with high levels of urate contamination, but sperm viability and morphology were similar (P > 0.05). Both SMI and viability of frozen‐thawed spermatozoa were higher (P < 0.05) for clean than for contaminated ejaculates. This is the first report on penguin ejaculate parameters, semen production, and preliminary methods for short‐ and long‐term semen storage. Zoo Biol 18:199–214, 1999. © 1999 Wiley‐Liss, Inc.     

Characteristics of chimpanzee (Pan troglodytes) ejaculates collected by rectal probe electrostimulation and by artificial vagina

This study compares characteristics of ejaculates collected from 16 adult male chimpanzees using rectal probe electrostimulation (RPE) and from 10 adult male chimpanzees trained to use an artificial vagina (AV). Ejaculate weight, semen volume, and sperm number were significantly lower (P < 0.01) and percentage liquefaction was significantly higher (P < 0.01) in ejaculates collected by RPE. Percentages of motile sperm and of live sperm in semen did not differ significantly between the two collection methods. Total amounts of protein and of α-glucosidase activity were significantly lower (P < 0.01) in seminal fluid from RPE samples. For ejaculates collected by RPE, semen volume correlated positively with protein (r = 0.8640, P < 0.001), fructose (r = 0.6976, P < 0.001), and citrate (r = 0.6976, P < 0.001); sperm number correlated positively with α-glucosidase activity (r = 0.6547, P < 0.001); and protein correlated positively with fructose (r = 0.5906, P < 0.002), citrate (r = 0.5926, P < 0.002) and α-glucosidase activity (r = 0.6006, P < 0.001). For ejaculates collected by AV, semen volume correlated positively with percentage liquefaction (r = 0.6058, P < 0.001), protein (r = 0.8055, P < 0.001), fructose (r = 0.6606, P < 0.001), and citrate (r = 0.8272, P < 0.001); sperm number correlated positively with percentage of motile sperm (r = 0.4196, P 0.004); percentage of motile sperm correlated positively with percentage of live sperm (r = 0.4388, P < 0.002); and, protein correlated positively with fructose (r = 0.6947, P < 0.002) and with citrate (r = 0.5926, P < 0.002). These data show that there is a significant difference in semen parameters and in biochemical parameters of ejaculates obtained by RPE and by AV. © 1995 Wiley-Liss, Inc.