Seasonal variations in semen characteristics, semen cryopreservation, estrus synchronization, and successful artificial insemination in the spotted deer (Axis axis)

Ten adult male spotted deer were monitored over a 2-year interval to determine seasonal variations in testicular size, semen characteristics and serum testosterone concentrations, and to determine if there was an association between season and type of antler. Mean (+/-S.E.M.) testicular volume (118.8+/-4.6 cm(3)), serum testosterone concentration (1.2+/-0.1 ng/mL), semen volume (4.1+/-0.6 mL), sperm concentration (338.3+/-24.9 x 10(6) mL(-1)), percentage of morphologically normal sperm (79.1+/-2.8%), and percentage of motile sperm (66.5+/-1.5%) were higher (P<0.05) in hard antler deer (peaked from March to May) than in deer with velvet antlers or in deer in which the antler has been shed. Thus, March-May was considered the physiologic breeding season for these deer; at this time, all stags had hard antlers. Furthermore, a Tris-citrate-based semen extender containing 4% glycerol and 20% egg-yolk was adequate for cryopreservation of semen. Estrus was induced with an implant containing norgestomet, timed transcervical AI was done with fresh semen, and 3 of 10 females were pregnant at 60 days, with fawns born 120 (premature), 240 and 243 days after AI. These results were considered a model for the use of assisted reproductive techniques to conserve other critically endangered deer species of India.     

Characterization of semen collected from beagles and captive Japanese black bears (Ursus thibetanus japonicus)

This study characterized semen collected from the Japanese black bear, Ursus thibetanus aponicus, to provide information on semen cryopreservation for artificial breeding. Preliminary studies using a beagle dog as the model species showed that sperm concentration and total sperm count were lower in semen collected by electroejaculation than in semen collected by digital manipulation, but that sperm motility, viability and morphology were similar. Characterization of semen obtained from Japanese black bears by electroejaculation under general anesthesia revealed that semen volume and total number of spermatozoa collected were lower; but that sperm concentration, motility, viability and morphology were equivalent to those reported in other ursids. When semen was collected via a catheter inserted into the urethra during the stimulation for ejaculation, the sperm concentration, total sperm count and motility were relatively higher than when semen was collected directly in a test tube. Specific normal semen characteristics (mean +/- SEM) were pH, 7.6 +/- 0.0; volume, 0.212 +/- 0.038 mL; sperm concentration, 361 +/- 100 x 10(6)/mL; total sperm count, 84.0 +/- 32.2 x 106; +++ motility, 30 +/- 5%; motility, 77 +/- 3%; viability 77 +/- 2%; and abnormal morphology, 11+/- 2%. These results suggest that semen can be collected from Japanese black bears by electroejaculation.     

Sperm production, testicular size, serum gonadotropins and testosterone levels in Merino and Corriedale breeds

The relationships between testis size, hormone secretion and sperm production were studied during the spring (December) and autumn (May) in rams of two breeds with different breeding seasons and body weights (Corriedale and Australian Merino) maintained on native pastures and under natural photoperiods in Uruguay. Blood samples were collected at 20-min intervals during a 260-360-min period in 13 rams (four Corriedale, nine Australian Merino) during the late spring and autumn. Rams were weighed and testis size was estimated by orchimetry at each time period. Sperm production was estimated during a 2-week period, 2 months before blood collection and during each week following every blood collection. There was no relationship between testicular size and sperm production measured at the same time, nor between live weight and sperm production. In contrast, testicular volume during the late spring was correlated with sperm production in the autumn (r = 0.65; P = 0.02). The autumn serum LH was higher in Corriedale than in Merino rams. LH pulsatility was unaffected by season, but LH pulse frequency tended to be higher in Corriedale than in Merino rams, particularly in the late spring (2.37 versus 1.56 pulses/6 h; P = 0.08). Serum testosterone concentration was similar in both breeds and seasons. FSH levels were higher in the late spring than in the autumn in both breeds (Corriedale: 2.83 +/- 0.48 versus 2.17 +/- 0.24 ng x mL(-1); Merino: 2.23 +/- 0.24 versus 1.88 +/- 0.17 ng x mL(-1)). FSH and testosterone concentrations during the late spring were positively correlated with autumn sperm production (P = 0.07 and P = 0.03, respectively). In conclusion, the present experiment suggests that LH secretion is not a good parameter for the prediction of sperm production. In contrast, in our conditions (breeds and native pastures) testicular size and testosterone or FSH concentrations from the late spring may be used to predict sperm production in the autumn.     

Characterization of male killer whale (Orcinus orca) sexual maturation and reproductive seasonality

Longitudinal serum testosterone concentrations (n=10 males) and semen production (n=2 males) in killer whales were evaluated to: (1) characterize fluctuations in serum testosterone concentrations with respect to reproductive maturity and season; (2) compare morphologic changes to estimated age of sexual maturity, based on changes in serum testosterone concentrations; and (3) evaluate seasonal changes in sperm production. Classification of reproductive status and age class was based on differences (P < 0.05) in serum testosterone concentrations according to age; juvenile males ranged from 1 to 7 years (mean+/-S.D. testosterone, 0.13+/-0.20 ng/mL), pubertal males from 8 to 12 years (2.88+/-3.20 ng/mL), and sexually mature animals were 13 years and older (5.57+/-2.90 ng/mL). For captive-born males, serum testosterone concentrations, total body length and height to width ratio of the dorsal fin were 0.7+/-0.7 ng/mL, 495.6+/-17.5 cm and 1.14+/-0.13c m, respectively, at puberty; at sexual maturity, these end points were 6.0+/-3.3 ng/mL, 548+/-20 cm and 1.36+/-0.1cm. Serum testosterone concentrations were higher (P<0.05) from March to June than from December to February in pubertal animals (4.2+/-3.4 ng/mL versus 1.4+/-2.6 ng/mL) and than from September to December in sexually mature animals (7.2+/-3.3 ng/mL versus 4.0+/-2.0 ng/mL). Ejaculates (n = 90) collected from two males had similar (P > 0.05) sperm concentrations across all months. These data represent the first comprehensive study on male testosterone concentrations during and after sexual maturation, and on reproductive seasonality in the killer whale.     

Seasonal variation in serum testosterone, testicular volume, and semen characteristics in the coyote (Canis latrans)

The coyote is a seasonally breeding mammal, with most copulations occurring between December and April (depending on location). The objective of this study was to characterize seasonal changes in serum testosterone concentrations, testicular volume, and ejaculate quantity and quality in captive male coyotes. There were seasonal differences in testicular volume, with the greatest volume (20.2+/-5.4cm2), mean+/-S.E.M.) in February, corresponding with peak breeding season. Circulating serum testosterone concentrations peaked (3.31+/-0.9 ng/mL) during January and were positively correlated (P< or =0.001, r=0.413) with testicular volume. Ejaculate volume (1.67+/-0.4 mL) and sperm concentration (549.2 x 10(6)+/-297.7 spermatozoa/mL) both peaked during January and February, consistent with the height of the breeding season. Ejaculate volume and sperm concentrations were positively correlated with testicular size (r=0.679, P< or =0.001 and r=0.499, P< or =0.001, respectively) and with serum testosterone concentrations (r=0.368, P< or =0.01 and r=0.208, P< or =0.05). Progressively motile, viable, and morphologically normal spermatozoa fluctuated seasonally, peaked (90.4+/-4.5, 84.8+/-4.1, and 87.9+/-2.9%) during the breeding season, and then subsequently declined (period of aspermatogenesis). All three of these end points were positively correlated with testicular size (r=0.589, P< or =0.001; r=0.586, P< or =0.001; and r=0.469; P< or =0.001) and serum testosterone (r=0.167, P< or =0.05; r=0.190, P< or =0.05; and r=0.221, P< or =0.01). In conclusion, there were intricate relationships among testosterone concentrations, testicular volume, and the production of both functionally intact and morphologically normal spermatozoa.     

B-mode ultrasonographic evaluation of paired testicular diameter of mature boars in relation to average total sperm numbers

Crossbred, meat-type terminal sire boars (n = 215) were randomly assigned by age group (240-300, 301-360, 361-420, 421-480, 481-540, 541-600, and >721 days). Stud boars were on a once or twice weekly semen collection schedule. Testis diameters, in duplicate, were obtained using B-mode ultrasonography. Summation of average left and right testis diameter within boar gave the paired testicular diameter (PTD). Average ejaculate volume, sperm concentration (sperm/ml), and total sperm numbers for each boar were determined using composite data (average values) obtained from the last four semen collections. There was a <0.5cm difference between left and right testis diameters, with the left testis being the larger of the two testes (P = 0.03). There was no difference in PTD found between age groups in this study. Conversely, a dramatic increase in average total sperm numbers (ATSN) was observed between boars of 240-300 days (57.0+/-27.4 x 10(9) sperm) and up to 420 days (118.6+/-33.6 x 10(9) sperm) of age. The ATSN (127+/-32.5 x 10(9) sperm) remained constant for the 421-480 to >721-day age groups. The correlation between PTD and ATSN was low (r = 0.24) in this study. The results of this study demonstrate that normal boars should exhibit <0.5cm diameter difference between testes. As observed in other studies, the left testis was usually larger than the right testis. Correlation of total sperm numbers in a boar ejaculate using a composite ejaculate score (average values) and PTD measurements obtained using B-mode ultrasonography was poor when used in boars >8 months of age.     

Investigations on reproductive physiology in the male Eurasian lynx (Lynx lynx)

This study characterized (in vivo) morphological and functional parameters of reproductive organs of adult male lynx (n = 3) prior to, during, and after the breeding season (n = 3). Size and morphology of the reproductive tract were monitored by transcutaneous (testes) and transrectal (accessory sex glands) ultrasonography. Semen was collected by electroejaculation. Ejaculate volume, sperm number, motility, and morphology of spermatozoa as well as testosterone concentrations in blood serum and feces were evaluated. The testes and prostate had seasonal changes in size and echotexture. The mean (+/- S.D.) maximum and minimum testicular volume were 2.8 +/- 0.8 cm3 and 1.5 +/- 0.3 cm3, respectively. Fecal testosterone concentrations were highest in February (1240 +/- 393 ng/g feces), with a second increase in May (971 +/- 202 ng/g feces), but concentrations were lowest in January (481 +/- 52.9 ng/g feces). Ejaculate volume, total sperm number and percentage of motile, and intact spermatozoa were maximal in March (the middle of the breeding season). In one of the eight litters, multiple paternity was proven; however, in the remaining seven litters, all 16 cubs were sired by the same male. This particular male had the most developed and active testes and best semen quality, which may be important for sperm competition.     

Seasonal emission of seminal coagulum and in vivo sperm dynamics in the black-handed spider monkey (Ateles geoffroyi)

The ejaculate of diverse primate species consists of two portions, liquid and solid; the latter, known as the seminal coagulum, is thought to sequester large numbers of sperm. In the black-handed spider monkey (Ateles geoffroyi), ejaculates collected by electroejaculation did not always contain seminal coagulum. The objective of the present study was to determine seasonal emission of seminal coagulum and in vivo sperm dynamics in the black-handed spider monkey. Seminal coagulum emission was related to season; it was more frequent in the dry season, coincident with maximal female fertility. Sperm concentration was higher (P = 0.02) in the dry season (dry vs. rainy season: 137.9 +/- 15.7 sperm/mL vs. 82.56 +/- 14.7 x1 0(6) sperm/mL; mean +/- S.E.M.) but also in ejaculates (collected during the rainy season) that had seminal coagulum (coagulum vs. no coagulum: 140.0 +/- 29.3 sperm/mL vs. 31.2+/-0.1 x 10(6) sperm/mL, P<0.001). In semen samples collected from the uterus after AI, the percentage of linearly motile sperm was higher during the dry season (dry vs. rainy: 9.1+/-2.1% vs. 5.9+/-2.5%), as well as whenever coagulum was present (coagulum vs. no coagulum: 13.0+/-3.2% vs. 2.0+/-0.9%, P<0.001).     

First postpartum estrus and pregnancy in the female collared peccary (Tayassu tajacu) from the amazon

The onset of sexual cycle postpartum was described in the collared peccary (Tayassu tajacu). Serum progesterone and 17beta-estradiol profiles, vaginal smears and external genitalia were analyzed in 20 animals housed with their piglets during the first postpartum month. The appearance of external genitalia showed no variation in any of the females: a shallow, reddish vulva, and vaginal mucus were constant features throughout the study. Based on hormonal profiles and vaginal smear cell patterns, 16 (80%) of the 20 peccaries showed signs of estrus and were considered cycling. The remaining four females (20%) did no show signs of estrus confirmed by low levels of progesterone (0.9+/-0.4 ng/mL) during the first postpartum month. In the cycling peccaries, a serum 17beta-estradiol peak (53.4+/-8.1 pg/mL) was observed on Day 7+/-1 postpartum, along with a linear increase in progesterone concentration from 3 (4.3+/-2.6 ng/mL) to 11 (30.8+/-4.9 ng/mL) days after this estradiol peak. Proportions of the different cells of the vaginal epithelium also changed in these females: superficial plus intermediate cells amounted to 76% of the cell total between Days 6 and 9 postpartum, corresponding to the estradiol peak. Nine (56%) of the 16 cycling females mated, indicated by the presence of sperm cells in their vaginal smears, and 6 (67%) became pregnant, reaching term. Non-pregnant cycling females (n=10) showed a steady decrease in serum progesterone concentration from 11 to 23 days after the estradiol peak, when basal levels were attained and a new estradiol peak registered, indicating the resumption of cyclicity in these females. The time interval between the two estradiol peaks was 23.5+/-2.1 days in these females. In pregnant females, progesterone concentrations continued to rise to levels of 60 ng/mL (n=6) 23 days after mating. These findings indicate that the lactating collared peccary female can become cycling and fertile during the early postpartum period, and that a predominance of superficial plus intermediate vaginal cells can be taken as the first sign of estrus.     

Somatostatin treatment affects testicular function in stallions

This study investigated the regulation of growth hormone (GH) release in stallions and tested the hypothesis that the somatotrophic axis influences testicular function. Basal plasma GH concentrations, effects of an experimental decrease of GH release on testicular function and an opioidergic regulation of GH release were investigated in Shetland stallions (n=6). No seasonal variations in plasma GH concentrations were found over a 12-month period. Treatment with the somatostatin analogue octreotid (100mg twice daily over 10 days) caused a decrease in semen motility from 38.7+/-8.4% progressively motile spermatozoa before treatment to 18.3+/-5.4% on day 3 after end of treatment (P<0.05). Values returned to 35.0+/-8.5% on day 5 after treatment. On the last day of octreotid treatment, a hCG stimulation test was performed (3000IU hCG i.v.). The hCG-induced testosterone release was significantly higher in saline treated than in octreotid pretreated animals (P<0.05). Neither plasma GH concentrations nor volume and density of ejaculates, total sperm count, or semen morphology were different between saline and octreotid treatments. Injection of the opioid antagonist naloxone (0.5mg/kg) significantly increased GH release in June (from 1.1+/-0.3ng/ml before to 3.7+/-2.2), while a minor and not significant increase occurred in January. In conclusion, our results indicate a non-seasonal basal GH release with a fine-modulation by season-dependent opioidergic mechanisms in the male horse. A transient decrease in semen motility and hCG-induced testosterone release following ocreotid treatment indicate a role of GH in the regulation of testicular function in stallions.     

Pregnancy in the domestic cat after vaginal or transcervical insemination with fresh and frozen semen

The objective was to compare pregnancy rates in domestic cats using fresh semen for intravaginal artificial insemination (IVI), either at the time of hCG treatment for induction of ovulation, or 28 h later, and to compare pregnancy rates following IVI or transcervical intrauterine insemination (IUI) of frozen-thawed semen. Eighteen queens were inseminated during 39 estrus cycles. Fresh semen with 13.5+/-5.4 x 10(6) sperm (range, 6.8-22 x 10(6)) collected by electroejaculation from four male cats was used in Experiment 1, and cryopreserved semen (20 x 10(6) sperm, with 70+/-5% post-thaw motility) from one male cat was used in Experiment 2. Serum concentrations of estradiol-17beta and progesterone were determined in most queens on the day of AI and again 30-40 days later. Treatment with 100 IU of hCG 3 days after the onset of estrus induced ovulation in 95% of treated queens. Pregnancy rates to IVI with fresh semen at the time of hCG administration versus 28 h later were not different (P=0.58); overall 33% (5/15) of the queens became pregnant. For frozen-thawed semen, AI was consistently done 28h after hCG administration; IUI and IVI resulted in pregnancy rates of 41.7% (5/12), whereas no queen (0/12) became pregnant by IVI (P=0.0083). In conclusion, an acceptable pregnancy rate was obtained with frozen-thawed semen in the domestic cat by non-surgical transcervical IUI; this method might also be useful in other small felids.     

Retrograde ejaculation occurs in the dog, but can be prevented by pre-treatment with phenylpropanolamine: a urodynamic study

Retrograde ejaculation is partial or total propulsion of semen from the posterior urethra into the urinary bladder; it is well characterized (and relatively common) in humans, with only a few reports in animals. Our objectives were to determine whether retrograde flow of semen occurred during ejaculation in mature dogs with normal fertility, and to determine the effects of phenylpropanolamine on this phenomenon (dose-titration, switch-back study). Retrograde ejaculation and urethral pressure profile measurements were evaluated (double-blind) in six dogs after 5 days of oral treatment with phenylpropanolamine (0, 2, 4, or 8mg/kg); all dogs received all treatments (at 2-week intervals). The number of sperm in the urine was determined before and after each manual sperm collection. Urethral pressure profiles were obtained three times during each procedure. In the absence of phenylpropanolamine, sperm were present in the bladder after semen collection in all dogs (number varied significantly among individuals). The mean (+/-S.D.) number of sperm in the bladder was 17.0+/-5.0, 18.5+/-1.2, 5.1+/-5.0, and 4.8+/-0.1x10(6) sperm for 0, 2, 4, and 8mg/kg, respectively (no significant difference between dogs given 4 or 8mg/kg, but both were significantly lower than those given 0 or 2mg/kg). This reduction was significantly correlated to the increase in mean urethral pressure at the level of the sphincter (39cm versus 59cm H(2)O in placebo-treated dogs versus those given 8mg/kg). In conclusion, we confirmed that retrograde ejaculation occurred during the ejaculatory process in normal dogs, and we demonstrated that phenylpropanolamine (4 or 8mg/kg once daily for 5 days before collection) increased urethral pressure and reduced the number of sperm voided into the bladder during ejaculation.     

Changes in plasma testosterone, thyroxine and triiodothyronine in relation to sperm production and remex moult in domestic ganders

Changes in plasma testosterone (T), thyroxine (T4), triiodothyronine (T3), semen output and remex moult were studied in domestic ganders. A bimodal pattern in both plasma T and sperm concentration was observed during the annual cycle. Ganders started to produce semen at the end of January; maximum semen volume (0.32 +/- 0.04 ml) and sperm concentration (148 +/- 38 x 10(3)/mm3) were reached in March and a marked decrease was observed after mid-April, when the moult of the remiges began. Plasma T3 levels peaked in February (9.7 +/- 0.6 nmol.l-1) and this peak coincided with maximum T concentrations (9.8-10.4 nmol.l-1). Elevated levels of T4 were found from late February until mid-April (31.0-33.6 nmol.l-1). Plasma T concentration was low at all stages of remex moult and regrowth. Decreased T4 levels were found in ganders during remex regrowth from the "brush" to half of the full primary growth stage. Higher plasma T4 levels were found before and after this stage of the moult. A reverse pattern was observed for T3 concentrations.     

Seasonal effects on attempts to synchronize estrus and ovulation by intravaginal application of progesterone-releasing device (PRID) in mares

To investigate seasonal effects on the efficacy of estrus synchronization in mares, we administered a progesterone-releasing device (PRID) intravaginally to eight Haflinger mares for 11 days. In January 3 of 8 mares responded to the treatment with estrus and ovulation, in March 7 with estrus and 6 of 7 mares with ovulation, in June 6 of 7 and in October 7 of 8 mares with estrus and ovulation. Follicle distribution patterns at PRID insertion were different between January/October, March/June and June/October (P<0.05). Number of follicles decreased during PRID treatment in January, March and June (difference of number of follicles at Day 12 minus number of follicles at Day 1: -4.2+/-2.7, -0.9+/-0.9 and -4.9+/-1.5 follicles), while it increased in October (3.9+/-1.2 follicles; P<0.05). Mean progesterone concentrations were lowest in January (0.3+/-0.1 ng mL(-1)) when compared with March (3.5+/-1.8 ng mL(-1); P=0.063), June (4.4+/-1.4 ng mL(-1); P<0.05) and October (2.2+/-0.9 ng mL(-1); P<0.05). At Day 2 of PRID treatment, mean progesterone concentrations significantly increased in all mares. Except from January, mean LH concentrations decreased within one day after PRID insertion and remained at low levels during treatments in January and March. Total secretion of LH during PRID-treatment was significantly lower in January and March when compared with June and October. In the 5 of 7 mares that ovulated during PRID treatment a distinct increase of plasma LH concentrations after ovulation was detected. Administration of the progesterone releasing intravaginal device PRID combined with the PGF2alpha analogue cloprostenol was able to induce estrus and ovulation in mares at different times of the year. However, efficacy of the treatment was not satisfactory concerning effectiveness in relation to season and synchrony of intervals from removal of PRID to ovulation in mares.     

Influence of ejaculation frequency on semen characteristics in chimpanzees (Pan troglodytes)

Semen samples were obtained by masturbation from 6 chimpanzees and the spontaneously liquefied fraction and the remaining coagulum were studied separately. When semen was collected once or twice a week, large intra-individual variations were observed for all measures. The liquefied fraction represented 26.5 +/- 3.2% (weighted mean +/- s.d.) of the total ejaculate but contained 51.3 +/- 3.8% of all emitted spermatozoa. Fructose concentration was higher in the coagulum than in the liquefied fraction (29.3 +/- 3.0 mumol/ml vs 12.0 +/- 2.7 mumol/ml, P less than 0.001) whereas acid phosphatase was less concentrated in the coagulum than in the liquefied fraction (3.5 +/- 0.3 x 10(3) IU/ml vs 13.0 +/- 0.9 x 10(3) IU/ml, P less than 0.001). L-Carnitine and citrate concentrations did not differ between the two fractions of the ejaculate. When semen collection was repeated every hour for 5 h, the ejaculate volume increased from 2.6 +/- 0.7 to 4.7 +/- 0.6 ml (P less than 0.001), whereas total sperm count decreased from 1278 +/- 872 x 10(6) to 587 +/- 329 x 10(6) (P less than 0.05) between the 1st and the 6th ejaculate. In the spontaneously liquefied fraction, the sperm count decreased from 984 to 369 x 10(6). The 6 successive ejaculates gave a total of 20.2 +/- 7.6 ml and 4278 +/- 2884 x 10(6) spermatozoa. The increase of the ejaculate volume was essentially due to an increase of the volume of the coagulum which closely correlated with total amount of fructose (from seminal vesicles) (r = 0.913, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Quality and in vitro fertilizing ability of cryopreserved cat spermatozoa obtained by urethral catheterization after medetomidine administration

Quality and in vitro fertilizing ability of frozen-thawed cat semen collected by urethral catheterization (CT) or electroejaculation (EE) after medetomidine administration were compared. Sperm collection was performed by an urinary tomcat catheter and, 4 days apart, by electroejaculation from each of eight tomcats. Results showed that semen collected by CT was characterized by lower volume (10.5+/-5.3 microL, P<0.05), higher sperm concentration (1868.4+/-999.8 x 10(6)/mL, P<0.05) and lower pH (7.0+/-0.4, P<0.05) than that collected by EE (67.1+/-25.9 microL, 542.9+/-577.9 x 10(6)/mL, and 7.9+/-0.4, respectively). Spermatozoa characteristics after thawing at 0, 3 and 6h did not differ between the two methods of collection. Also cleavage rate and embryo production from oocytes fertilized with frozen-thawed spermatozoa collected by CT or EE showed no significant differences (P>0.05). In conclusion, the results obtained in the present study indicate that good quality freezable semen can be collected from cats by urethral catheterization after medetomidine administration. This new method of semen collection appears very useful in practice and, compared with the electroejaculation protocol, permits to obtain semen samples characterized by a higher concentration of spermatozoa, lower total volume and lower pH.     

Semen characteristics after vasectomy in the ram

The objective of this study was to monitor the changes in semen characteristics in vasectomized rams and to determine if infertility was present 14 days after vasectomy. Experiments were performed using five cross-breed rams, aged between 18 and 30 months. Semen was collected weekly by artificial vagina from 2 months before to 5 months after vasectomy. After sexual rest for 10 days, vasectomy was performed by the cranial midscrotal approach. In all ejaculates the volume, concentration, total sperm number, motility and morphology (normal spermatozoa, loose heads) were determined and sperm viability (SYBR-14/PI) was evaluated in all semen samples collected after vasectomy. In the first ejaculate obtained 14 days post vasectomy all rams showed a significant (P < 0.05) drop in mean volume (from 1.2 to 0.5 mL), total sperm count (from 5176.8 to 51.1 x 10(6)) and morphologically normal sperm (from 84.1 to 15.7%), when compared to the last prevasectomy collection. We could also demonstrate a positive correlation (r = 0.89) between the individual cumulative total number of spermatozoa after vasectomy and the scrotal circumference measured before vasectomy. Sperm motility and viability could never be demonstrated after vasectomy and normal spermatozoa continuously decreased concomitant with an increase in loose heads. On post mortem examination 5 months after surgery, spermatocele formation and multiple sperm granulomas were present in all five rams. Our results show that in the first ejaculate collected by artificial vagina 14 days after vasectomy, no motile and viable spermatozoa could be detected. Despite weekly collections during a 5-month period after sterilization, azoospermia could never be achieved.     

Androgen binding protein, sperm production, semen output and LH and testosterone profiles in young postpubertal bulls

An androgen binding protein (ABP), which binds 5alpha-dihydrotestosterone with high affinity (Ka = 0.3 x 10(9) M(-1)), has been demonstrated in testicular and epididymal cytosols of 5 young post pubertal bulls (15-17 months old) of the Montbeliarde dairy breed. Simultaneously, daily sperm production (DSP), semen output and plasma LH and testosterone concentrations (from frequent samplings) were determined. ABP levels were 21 fmoles/mg protein in testis and 59, 22 and 43 fmoles/mg, respectively, in caput, corpus and cauda epididymis. Mean DSP, per gram of testis, was 16.6 x 10(6) spermatozoa, and the mean sperm output was approximately 1.5 x 10(9) spermatozoa per ejaculate. Mean LH and testosterone levels were 1.5 ng/ml and 2.1 ng/ml, respectively. One bull (882) was clearly distinguishable from the others, in showing higher ABP and testosterone levels together with a lower daily sperm production. Results of this study may (1) suggest a physiological role of ABP in sperm epididymal maturation and (2) give a new parameter in the evaluation of individual bulls testicular function.     

Semen quality and sperm output of Yankasa rams at different ages

Three groups of three Yankasa rams aged 1.4, 2.4, and 3.4 yr, weighing 32.8 +/- 0.8, 47.9 +/- 1.4, and 48.8 +/- 1.3 kg, and with scrotal circumferences measuring 26.8 +/- 0.9, 28.9 +/- 0.3, and 30.3 +/- 1.3 cm (mean +/- SEM), respectively, were used for this study. The rams were ejaculated once per day for 14 d using an artificial vagina and their semen quality and sperm output determined. For the three groups, ejaculate volume, sperm concentration, sperm motility, percentage of morphologically normal sperm, and total sperm output per ejaculate averaged 0.72 +/- 0.03, 0.90 +/- 0.04, and 0.88 +/- 0.03 ml; 3.421 +/- 0.133, 4.025 +/- 0.179, and 4.673 +/- 0.184 x 10(9)/ml; 83.2 +/- 2.3, 84.6 +/- 1.5, and 74.0 +/- 2.4%; 96.2 +/- 0.3, 96.0 +/- 0.4, and 95.4 +/- 0.4%; and 2.469 +/- 0.141, 3.663 +/- 0.237, and 4.163 +/- 0.247 x 10(9) sperm, respectively. Differences between groups were significant for all semen traits except for percentage of morphologically normal sperm. Total sperm output per ejaculate (Y; x 10(9)) was significantly correlated with scrotal circumference (X; cm) by the geometric regression equation Y = 0.000128 X(3.03) (r = 0.71; P < 0.05). Ejaculate characteristics were not influenced by day of collection except for percentage of morphologically normal sperm, which was significantly (P < 0.01) lower on the first day of collection.     

Seasonal variations of LH, prolactin, androstenedione, testosterone and testicular FSH binding in the male blue fox (Alopex lagopus)

The seasonal changes in testicular weight in the blue fox were associated with considerable variations in plasma concentrations of LH, prolactin, androstenedione and testosterone and in FSH-binding capacity of the testis. An increase in LH secretion and a 5-fold increase in FSH-binding capacity were observed during December and January, as testis weight increased rapidly. LH levels fell during March when testicular weight was maximal. Plasma androgen concentrations reached their peak values in the second half of March (androstenedione: 0.9 +/- 0.1 ng/ml: testosterone: 3.6 +/- 0.6 ng/ml). A small temporary increase in LH was seen in May and June after the breeding season as testicular weight declined rapidly before levels returned to the basal state (0.5-7 ng/ml) that lasted until December. There were clear seasonal variations in the androgenic response of the testis to LH challenge. Plasma prolactin concentrations (2-3 ng/ml) were basal from August until the end of March when levels rose steadily to reach peak values (up to 13 ng/ml) in May and June just before maximum daylength and temperature. The circannual variations in plasma prolactin after castration were indistinguishable from those in intact animals, but LH concentrations were higher than normal for at least 1 year after castration.