Electroejaculation, semen characteristics and serum testosterone concentrations of free-ranging african elephants (Loxodonta africana)

A regimented electroejaculation protocol (120 electrical stimulations; 10-30 V) was used to collect semen and characterize ejaculate quality from 9 adult, free-ranging African elephants under anaesthesia. Eight of the 9 ejaculates contained high concentrations of progressively motile spermatozoa. The overall mean ejaculate volume, sperm concentration/ml ejaculate, sperm motility, sperm status and ejaculate pH were 93.3 ml, 2408.6 X 10(6) spermatozoa/ml, 70%, 3.9 and 7.4, respectively. A high percentage (mean 77.5%) of spermatozoa within each ejaculate was morphologically normal. Of the aberrant spermatozoa, 72% had a cytoplasmic droplet defect. When sperm viability was tested in vitro at 37 degrees C, sperm motility rating declined by at least half of the initial assessment within 3.5 h of semen collection. Generally, spermatozoa maintained motility in vitro for less than 6 h. Serum testosterone ranged from 1.4 to 8.2 ng/ml in 4 males evaluated in the morning (07:30-08:00 h). In 4 of the 5 bulls assessed in the afternoon (15:00-18:00 h), testosterone levels were less than 0.9 ng/ml. The remaining bull, evaluated at 16:00 h, had exceptionally high testosterone concentrations (peak 25.6 ng/ml) and a preputial discharge potentially indicative of 'musth'. The present study demonstrates that high quality semen can be collected consistently from the African elephant and that striking differences exist in serum testosterone amongst free-ranging males which may be due, in part, to a diurnal rhythm.     

Testicular development and its relationship to semen production in Murrah buffalo bulls

The objectives of this study were to determine the relationship of age and body weight to testicular development and to establish norms for breeding soundness evaluations of Murrah buffalo bulls. Testicular measurements of 133 Murrah buffalo bulls of various ages were recorded with a caliper and a tape. Semen was collected twice a week for 5 weeks from groups of bulls which were 25-36 (n=17), 37-48 (n=16), 49-60 (n=14), of >60 (n=10) months of age. After examining volume, sperm concentration, and progressive motility semen was diluted in Tris-citric acid-egg yolk-fructose extender and frozen in 0.5 ml French straws. Testicular measurements of buffalo bulls were lower than those recorded for European breeds of cattle bulls. Nevertheless, like cattle bulls, scrotal circumference was highly correlated with other testicular measurements. Also, it had a significant positive relationship with semen volume and sperm concentration per ejaculate. Average sperm output per week in order of increasing age group was 15.3, 18.2, 19.8 and 23.6 x 10(9). Corresponding values for sperm output per week per gram of testis were 59.1, 45.8, 41.1, 36.2 x 10(6) indicating a reduction in spermatogenesis per unit of testis with advancing age. Compared to European breeds, daily sperm output in Murrah bulls was nearly 45% lower, presumably due to their nearly 40% lower scrotal circumference than Holstein bulls of the same age. These results indicate that in buffalo, as in cattle, scrotal circumference is a useful indicator of potential sperm output and may serve as an important criterion for selecting young bulls as AI sires.     

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.     

Quality and freezing qualities of first and second ejaculates collected from endangered Gulf Coast Native rams

The Gulf Coast Native sheep, or Louisiana Native sheep, is an endangered previously feral domestic sheep population of European origin that has been under natural selection pressure for reproductive survival in their transplanted range while roaming in the southern Gulf Coast Region of the United States. This sheep population has an increased natural resistance to internal parasites, breeds year-around and has a greater percentage of live lambs as compared with other breeds of sheep raised in similar environments. To preserve the genetic diversity of this important feral sheep population, semen was collected by electro-ejaculation and subjected to cryopreservation for subsequent storage in a genome resource bank. Unrelated rams (n=5) were collected 3 days-a-week, allowing at least 2 days of rest between collections. Two ejaculates were obtained from each ram per collection day, with the second collection conducted 10min after the first ejaculation. Semen was processed using the standard Salamon cryopreservation procedure in a Tris-yolk-glycerol extender, frozen in 0.5ml plastic straws using liquid nitrogen (LN(2)) vapor and stored in LN(2). Each ejaculate was evaluated for volume, sperm concentration/ml (x10(9)/ml), number of spermatozoa/ejaculate (x10(9)), sperm progressive motility (%) for pre-cooled semen, cooled semen and semen after thawing. For the five rams, each semen variable for the first ejaculate was compared with that of the second ejaculate collected 10min later. The mean semen volume, sperm concentration and number of spermatozoa per ejaculate obtained from the first ejaculate were significantly greater (P< or =0.01) than those of the second ejaculate (comparisons being 1.62 and 1.06; 3.2 and 1.5; 5.4 and 1.8, respectively). Overall, the mean motility of pre-cooled (22 degrees Celsius), cooled (5 degrees Celsius) and frozen (-196 degrees Celsius) post-thawed spermatozoa was less (P< or =0.01) in the first ejaculate (71.5, 64.8 and 34.1%, respectively) compared with that of the second ejaculate (75, 72.4 and 44.1%, respectively). Conversely, no differences were detected in loss in the percent progressive motility of sperm from cooled sperm to post-thaw sperm from the first and second ejaculates. In summary, our findings suggest sperm collected during the second ejaculate 10min after the first ejaculate of rams survives thawing with a greater rate of progressive motility than that of the first ejaculate. The ability to collect two consecutive ejaculates in a short period by electro-ejaculation could be valuable for gamete resource banking and preserving genetic diversity of the Gulf Coast Native sheep.     

Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years.

OBJECTIVE: To determine whether the quality of semen has changed in a group of over 500 Scottish men born between 1951 and 1973. DESIGN: Retrospective review of data on semen quality collected in a single laboratory over 11 years and according to World Health Organisation guidelines. SETTING: Programme of gamete biology research funded by Medical Research Council. SUBJECTS: 577 volunteer semen donors. Of these, 171 were born before 1959, 120 were born in 1960-4, 171 in 1965-9, and 115 in 1970-4. MAIN OUTCOME MEASURES: Conventional criteria of semen quality including semen volume (ml), sperm concentration (10(6)/ml), overall motility (% motile), total number of sperm in the ejaculate (10(6)), and total number of motile sperm in the ejaculate (10(6)). RESULTS: When the four birth cohort groups were compared a later year of birth was associated with a lower sperm concentration, a lower total number of sperm in the ejaculate, and a lower number of motile sperm in the ejaculate. The median sperm concentration fell from 98x10(6)/ml among donors born before 1959 to 78x10(6)/ml among donors born after 1970 (P=0.002). The total number of sperm in the ejaculate fell from 301x10(6) to 214x10(6) (P=0.0005), and the total number of motile sperm in the ejaculate fell from 169.7x10(6) to 129.0x10(6) (P=0.0065). CONCLUSION: This study provides direct evidence that semen quality is deteriorating, with a later year of birth being significantly associated with a reduced number of sperm in adult life.     

Dietary supplementation with a source of omega-3 fatty acids increases sperm number and the duration of ejaculation in boars

Development of nutritional strategies to increase the production of fertile sperm would further enhance the distribution of superior genetic material by AI. The objective was to determine the effects of a dietary source of omega-3 fatty acids in boars on semen characteristics and sexual behavior. Boars were fed daily 2.2 kg of a diet top-dressed with 0.3 kg of corn (controls; n=12) or 0.3 kg of a supplement containing 31% omega-3 fatty acids (n=12) for 16 weeks. Semen was collected weekly and for boars that received the supplement containing omega-3 fatty acids, total sperm per ejaculate averaged 84.3+/-2.3 x 10(9) (mean+/-S.E.M.) during Weeks 0-7, and increased (P=0.02) to 95.6+/-2.3 x 10(9) during Weeks 8-15. Control boars averaged 86.3+/-2.3 x 10(9) sperm per ejaculate during Weeks 0-7 and 86.4+/-2.3 x 10(9) during Weeks 8-15. Other semen characteristics were similar (P>0.1) between groups. Duration of ejaculation was affected by treatment (343.9s for controls and 388.8s for boars fed omega-3 fatty acids; S.E.M.=15.7; P=0.05). In summary, semen characteristics and sexual behavior were altered in boars fed a supplement containing omega-3 fatty acids. Boar semen is typically diluted to create AI doses containing 3 x 10(9) sperm each; therefore, use of the supplement increased the number of potential AI doses by approximately three per ejaculate after the initial 7 week supplementation period.     

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.     

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)     

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.     

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.     

Interpretation of semen analysis among infertile couples.

Among the male partners of 1074 infertile couples the mean results of semen analysis were sperm count 78 X 10(6)/ml, seminal volume 4.0 ml, proportion of progressively motile sperm 54%, proportion of sperm with normal morphologic features 81.4% and total motile sperm count 152.3 X 10(6) per ejaculate. After excluding 65 couples who chose donor insemination and 300 with known female causes of infertility, the cumulative pregnancy rates in the remaining 709 couples were higher with increasing sperm density and motility and seminal volume, but the higher rates were significant only when these variables were combined into total motile sperm count per ejaculate. The cumulative pregnancy rates were 20% with a total motile sperm count of 9 X 10(6) or less, 37% with a count of 10 to 19 X 10(6) and 52% with a count of 20 X 10(6) or more (p = 0.001). Counts higher than 20 X 10(6) were not associated with a further improvement in pregnancy rates, but variability in the results was high, which suggests that the test should be repeated as necessary to determine the true range. Although standards for these and other seminal variables are ill defined, the total motile sperm count incorporates the most useful prognostic information from semen analysis, and the associated pregnancy rates can help guide clinical decisions.     

Manual semen collection from a Grevy's zebra stallion (Equus grevyi), onset of sperm production, semen characteristics, and cryopreservation of semen, with a comparison to the sperm production from a Grant's Zebra stallion (Equus burchelli boehmi)

A manual technique was used to collect representative ejaculates from an unrestrained Grevy's zebra stallion beginning at 13 mo of age to determine the onset of sperm production, to calculate the number of spermatozoa produced per ejaculate, and to determine any seasonality associated with sperm production. Spermatozoa first appeared in the ejaculate at 31 mo of age. By 48 mo of age the zebra was producing up to 40 billion spermatozoa per ejaculate. Progressive sperm motility ranged from 75 to 95%. Gel-free semen volume averaged 75 to 120 ml/ejaculate. Gel volume ranged from 0 to 1100 ml/ejaculate. Semen was frozen in 2 different extenders in 0.5-ml PVC straws. The post-thaw motility of cryopreserved spermatozoa ranged from 30 to 70%. A domestic horse mare became pregnant on the first cycle after insemination with frozen-thawed spermatozoa from this zebra. Sperm production data obtained from semen collections made on a Grant's Zebra stallion from 3 to 8 yr of age is presented for comparison of the 2 species.     

Semen characteristics of Muturu Bulls--Bos brachyceros

Six mature Muturu Bulls were elecroejaculated once a week for nine weeks to study their semen quality and ejaculate characteristics. The semen volume was 1.8 ml +/- 0.1, the sperm concentration 2.16 x 10(8)/ml +/- 0.29, and the progressive sperm motility 36.2% +/- 2.6. Morphologically normal sperm averaged 70.0% +/- 3.1, primary abnormalities 13.4% +/- 1.0 and secondary abnormalities 15.1% +/- 2.3. Except in one bull, no measurable levels of fructose were observed. The contents of major cations and chloride ions in whole semen and seminal plasma were also determined.     

Age-related changes in body weight,scrotal size and plasma testosterone levels in buffalo bulls (Bubalus bubalis)

Body weight, testicle size and peripheral testosterone concentrations were measured in 35 water buffalo bulls at 5, 15, 17, 21, 25 and 38 months of age. These parameters were studied in all animals during the same month (October), so the changes due to age were independent of changes in photoperiod and temperature. Body weight increased linearly with age. The testicular size measured in terms of scrotal circumference as related to age, showed a curvilinear increase; the average rate of testicular growth was maximum between 15 and 25 months. Plasma testosterone levels were low between 5 and 21 months. A significant rise in plasma concentration of testosterone was observed at 25 months reaching peak levels at 38 months. The mean age of sexually mature bulls at the time of first ejaculation of semen with motile sperm, was 24.9±0.9 months (n=9). It has been concluded that in the Nili-Ravi buffalo bulls the sexually quiescent period (prepubertal) extends up to 15 months of age and sexual maturation as indicated by the presence of motile sperm in the ejaculate is attained at about 25 months.     

Environmental factors contributed to circannual rhythm of semen quality

We investigated whether human semen parameters present circannual rhythm or not, and whether environmental factors exert on semen quality. This retrospective study used data of patients mainly from Reproductive Medicine Center and Urology and Andrology Clinic of a general hospital in China. Sperm concentration and motility were measured by computer aided sperm analysis (CASA). Sperm morphology was scored based on the strict criteria (WHO, 2010). The Kruskal–Wallis rank test was used to investigate the relationship between semen parameters and season/month. Partial correlation coefficients were used to analyze the relationship between semen parameters and environmental factors. In this study, we found that sperm concentration and total amount per ejaculate were significantly lower in summer and higher in winter. But, sperm progressive motility and motility were significantly higher in spring and summer (from March to June), lower in autumn and winter (September and October). Unexpectedly, normal sperm morphology and mixed agglutination reaction (MAR) positive rate didn’t vary along with season or month. Furthermore, temperature was negatively related to sperm concentration and total amount per ejaculate. Precipitation was positively associated with progressive motility and normal sperm morphology, but negatively related to sperm head defect percentage. The length of sunlight was positively related to progressive motility. The Air Quality Index (AQI) was positively associated with semen volume and sperm total amount per ejaculate. These suggest seasonal and monthly variation underlying some semen parameters.     

Variations in seminal parameters over a 12-month period in captive bonnet monkeys

Semen samples were collected from adult fertile bonnet monkeys twice a month by penile electroejaculation for twelve consecutive months. Various parameters like semen volume, weight of ejaculate and coagulum, sperm count, sperm motility, sperm morphology, and functional parameters e.g. plasma membrane integrity,in vitro nuclear chromatin decondensation and acrosomal status were evaluated to assess within and between animal variations. Effects of seasonality, if any, on quantity and quality of semen were also studied. Considerable intra- and inter-individual variations in the geometric mean values were observed for semen volume, weights of ejaculate and coagulum, and sperm counts during the study period. On the other hand, sperm motility, morphology, and functional parameters showed less within and between animal variations. Results on motility, morphology, and functional parameters indicated that good semen quality was maintained throughout the year. Various routine and functional parameters did not show any annual variations. The diurnal rhythmicity in circulatory testosterone levels was observed throughout the year. The study shows lack of seasonality in exocrine and endocrine testicular functions and further suggests that motility, morphology, and functional parameters are better indicators of semen quality in captive bonnet monkeys.     

Effects of bull and heparin and sperm concentrations on in vitro fertilization of buffalo (Bubalus bubalis ) oocytes matured in vitro

A study was undertaken to assess the ability of spermatozoa from 6 buffalo bulls, at different levels of heparin and sperm concentrations, to achieve an acceptable level of fertilization in vitro. Frozen-thawed spermatozoa, 3 dosages of heparin (0, 10 and 100 ug/ml) in the presence and absence of penicillamine, hypotaurine and epinephrine (PHE), and 4 sperm concentrations (1 x 10(6), 2 x 10(6), 3 x 10(6) and 4 x 10(6) /ml) were studied using 3202 buffalo oocytes. The mean proportions of fertilized oocytes in the group treated with 10 ug/ml of heparin were significantly higher (P<0.05) with the semen of Bulls A, B and C (44.7 to 64.3%) than in medium devoid of heparin. An increase in the dosage of heparin from 10 ug/ml to 100 ug/ml reduced the overall fertilization rate. However, optimal fertilization (30.9%) at 100 ug/ml heparin was observed for semen from Bull D. Bulls E and F yielded the lowest fertilization rate (9.6 and 14.2%, respectively) at the above mentioned heparin dosage. Analysis of sperm density revealed that a concentration of 2 x 10(6) spermatozoa yielded optimal fertilization rates in vitro. Higher sperm concentrations (3 x 10(6) or 4 x 10(6)) resulted in higher oocyte penetration rates but gave rise to polyspermy.     

Postpubertal sexual development in merino rams after differential feeding through puberty

Spring-born Merino ram lambs were reared on 130%, 165% or 200% of recommended maintenance energy requirements from 7 to 12 mo of age and were then placed on a common plane of nutrition from 12 to 25 mo of age. During the latter 13 mo, the 24 rams were studied for changes in live-weight and testicle characteristics. Semen characteristics and sexual activity were observed from 12 to 19 mo of age. At the beginning of the study, groups coming from low (L), medium (M), and high (H) nutrition had liveweights of 38.9, 46.8, and 53.6 kg (P < 0.05) and scrotal circumferences of 24.6, 28.9, and 32.1 cm (P < 0.05), respectively. When the rams were given common feed conditions, the differences between groups in both liveweight and scrotal circumference quickly decreased and were not significant by the sixth month. No significant differences existed between groups in ejaculate characteristics during semen collection, except in sperm density which, at the end of semen collection, was significantly (P < 0.05) higher in Group M (3.98 x 10(9)/ml) than in Group L (2.55 x 10(9)/ml). However, in analyses of pooled data, there were significant differences between months of collection in sperm density, total number of sperm per ejaculate, and percentages of live and abnormal sperm. The data indicate that differential nutrition during the first year of life will affect some reproductive characters contemporaneously, but with restored feeding, reproductive differences are resolved more quickly than those in liveweight and the changes proceed despite countervailing photoperiodic influences.