Quantity Of Ejaculate Research Articles

Male allocation to ejaculation and mating effort imposes different life history trade-offs.

When males compete, sexual selection favors reproductive traits that increase their mating or fertilization success (pre- and postcopulatory sexual selection). It is assumed that males face a trade-off between these 2 types of sexual traits because they both draw from the same pool of resources. Consequently, allocation into mate acquisition or ejaculation should create similar trade-offs with other key life history traits. Tests of these assumptions are exceedingly rare. Males only ejaculate after they mate, and the costs of ejaculation are therefore highly confounded with those of mating effort. Consequently, little is known about how each component of reproductive allocation affects a male's future performance. Here, we ran an experiment using a novel technique to distinguish the life history costs of mating effort and ejaculation for mosquitofish (Gambusia holbrooki). We compared manipulated males (mate without ejaculation), control males (mate and ejaculate), and naïve males (neither mate nor ejaculate) continuously housed with a female and 2 rival males. We assessed their growth, somatic maintenance, mating and fighting behavior, and sperm traits after 8 and 16 weeks. Past mating effort significantly lowered a male's future mating effort and growth, but not his sperm production, while past sperm release significantly lowered a male's future ejaculate quantity, but not his mating effort. Immune response was the only trait impacted by both past mating effort and past ejaculation. These findings challenge the assumption that male reproductive allocation draws from a common pool of resources to generate similar life history costs later in life. Instead, we provide clear evidence that allocation into traits under pre- and postcopulatory sexual selection have different trait-specific effects on subsequent male reproductive performance.

The female Euscepes postfasciatus refractory period is induced by the male but length is determined by the female

Females of many animals mate multiple times during their lives (i.e., polyandry). The period between matings (mating interval) is called the refractory period (RP). In the West Indian sweet potato weevil (Euscepes postfasciatus), males use the ejaculate to induce the RP in females to prevent re-mating. By measuring the RP, a large variation of 1–49 days was observed. This variation may be due to the males (ejaculate quantity and quality) and females (ejaculate sensitivity/degradation ability and body size) and their interactions, but the exact mechanisms are currently unclear. Here, we investigated a tendency towards a particular female RP duration and the associated traits of males and females to test the following three factors responsible for variation in the length of the RP: male manipulation of ejaculate volume, individual differences in male ejaculation substances, and ejaculate sensitivity/degradation ability in females. We prepared virgin males and females to create mating pairs. The following day, another mate was introduced to the females, and the first RP was measured. The same procedure was used for measuring the second RP. The males were also provided with another female (second female), mated, and then the RP of the second female was measured. In addition, the relationship between the length of the RP and female fitness was investigated. The results showed that there was a significant positive correlation between the first and second RP in the focal females, while no significant correlation was observed between the RP of the first and second females induced by the same male. It was also found that the length of the RP did not affect female fitness. This indicated that the males did not adaptively manipulate ejaculation volume depending on the quality of the females, and variance in the length of the RP may be explained by variation in the female physiological ability against ejaculate.

Pathogenetic aspects of male subfertility in obesity: a review of experimental and clinical studies

The obesity epidemic in the 21st century is an actual public health problem. The obesity is the cause of many pathological conditions in humans. According to the latest data there is a link between reproductive health and obesity, in particular, with a decrease in the quality and quantity of ejaculate in men. Nevertheless information about the effect of obesity on the parameters of spermogram is controversial. The purpose of this review was to study the relationship of body mass index with sperm parameters in animal experiments and indicators in men of reproductive age. This article reviewed the results of studies conducted on animals, as well as systematic reviews of studies conducted in a clinical setting.

Fishery-exteriors characteristics of the brooders of brown trout, rainbow trout and brook trout

This study aims to determine the reproductive indices of three types of salmon fish: brown trout (Salmo trutta morfa fario Linnaeus (1758), rainbow trout (Oncorhynchus mykiss Walbaum, 1792) and brook trout (Salvelinus fontinalis Mitchill, 1814) in aquaculture. For this purpose, 10 females and 10 males of each species were selected on an analogous basis and the main fishery-exteriors and reproductive characteristics were identified. The researching of relative fertility permit to establish that this indicator in brook trout females was 18.36% higher compared to rainbow trout, however, by 7.5% lower compared to the brown trout. It was found that brook trout eggs had less weight and size in comparison with other studied species. In particular, the weight and diameter of the eggs were 2.89 and 9.7% respectively lower than of rainbow trout, as well as 8.1 and 3.44% respectively lower compared to the brown trout. When studying the quantity of ejaculate, it was found that on average, brook trout males had 16.95% less of ejaculates compared to rainbow trout males, but 79.6% more than of brown trout males. When comparing the main indices of the brooders body of the studied species, it was found that the condition factor of the brook trout and rainbow trout females was quite high at 1.55–1.57, the brown trout one was 1.35, and the profile index respectively was 3.5, 3.52 and 4.0. The males' condition factor of brook trout, rainbow trout and brown trout was respectively 1.64, 1.52 and 1.35. Fishery-exteriors indicators met the requirements of brooders species and age specificity norms of the studied fish species.

The Importance of Male Ejaculation for Female Sexual Satisfaction and Function

IntroductionAlthough links between ejaculatory control or intravaginal ejaculatory latency time and female sexual functioning have frequently been reported in the past, no study has investigated the importance of other male ejaculatory characteristics, such as ejaculation volume and intensity, for women’s sexuality. AimTo assess the importance of subjectively perceived ejaculation intensity and ejaculation volume for female sexual function and satisfaction. MethodsThis was a cross-sectional online survey including 240 sexually active, heterosexual women (median age 27.4 years), using study-specific questions and validated questionnaires. Main Outcome MeasureResults are presented as means, percentages, and age-controlled partial correlation coefficients of the main study variables. Results50.43% of women considered it very important that the partner ejaculates during intercourse. 18.3% of women preferred that the partner ejaculates before they reach orgasm, whereas for 53.5% this did not matter. 22.6% of women stated that they experienced a more intense orgasm when their partner ejaculated during vaginal intercourse. 17.4% reported that they definitely experienced a more intensive orgasm depending on the intensity of their partner’s ejaculation, whereas for 17.8% this did not matter at all. 20.9% of women did not feel that their orgasm was more intense depending on the subjectively felt ejaculate quantity, whereas the majority (37.9%) stated that it did not matter. 13.1% of women regarded the quantity of expelled ejaculate as an expression of their own sexual attractiveness. Women stating that they experienced more intense orgasms when the partner ejaculated, when the partner experienced a more intense ejaculation, and when he expelled a greater ejaculate quantity also reported better lifelong orgasmic function (r = 0.24, r = 0.15, r = .26, respectively) and more lifelong sexual satisfaction (r = .29, r = .15, r = 26, respectively). Clinical ImplicationsThe perception of ejaculatory characteristics can be related to the female partner’s sexual satisfaction and overall sexual functioning. Strength & LimitationsThis is the very first study to explore the importance of male ejaculation volume and intensity for women’s sexual functioning. Data are of self-report nature and ejaculation characteristics were not objectively measured but by women’s self-report. ConclusionAlthough male ejaculation and its different aspects seem to play an important role for women, the study demonstrates a considerable variability of women’s attitudes toward ejaculatory characteristics. Further research is required to examine the sources of this variability.Burri A, Buchmeier J, Porst H. The importance of male ejaculation for female sexual satisfaction and function. J Sex Med 2018;15:1600–1608.

The effect of different extenders on the sperm motilityand viability of frozen Turkey semen

This study was conducted to develop long-term storage methods for turkey semen using different extenders. During the study, the massage method was used twice a week to collect the semen from five turkeys, a total of 44 times. The collected fresh semen’s average ejaculate quantity, sperm concentration, motility and vitality values were determined as 0.22±0.01 ml, 3.5±0.17 x109 sp/ml, 77.0±1.44% and 86.2±0.95 % respectively. In this study, glucose (G) including 5% Dimethyl sulphoxide (DMSO) cryoprotective, tris-glucose (TG), lactated Ringer’s (LR), and lactated Ringer’s glucose (LRG) extenders were used. The Turkey semen was combined and divided into four equal parts, and subsequently diluted at a ratio of 1:3 and equilibrated at +4°C for 90 minutes. Following equilibration, the samples were frozen in liquid nitrogen vapor to - 80°C for five minutes, and stored at -196°C in liquid nitrogen. After freezing and thawing, the highest motility value was obtained from the G extender (43.3% ±1.62%) followed by LRG (24.6±1.53%), LR (12.6±0.92%) and TG (12.2±0.66%). The vitality values were recorded as 55.8±1.89%, 23.8±1.58%, 21.5±1.10% and 36.5±1.59% respectively. The motility and vitality values were significantly (p less than 0.01) more for the glucose extender than those for other extenders. Therefore, it was concluded that glucose extender is better option for the long-term storage of Turkey semen.

Geographic variation in sperm and ejaculate quantity and quality of horseshoe crabs

Populations of a single species may vary substantially in sexually selected traits. However, the majority of studies investigating such variation across populations have focused on traits important for pre-copulatory reproductive success, such as male ornamentation or song. Relatively fewer studies have investigated whether traits important in post-copulatory sexual selection vary across populations. In this study, we examine how sperm and ejaculate quantity and quality in the American horseshoe crab, Limulus polyphemus differ at six sites, from Maine to Florida. Horseshoe crabs from these sites differ in many respects, including average body size, age, and the risk and intensity of sperm competition as measured by the operational sex ratio. We find that sperm and ejaculate quantity and quality significantly differ across this range and that this variation persists after taking body size and age into account. Sperm traits also do not follow strictly linear latitudinal clines. Finally, we find that the site-specific operational sex ratio correlates with changes in sperm and ejaculate quantity. This latter result may indicate that the same processes that lead to variation in post-copulatory sexually selected traits across related species may also promote trait divergence across populations of the same species. This study describes variation in sperm and ejaculate traits from horseshoe crabs collected at six sites from Maine to Florida. While geographic variation has been described for many traits, relatively few studies have demonstrated that sperm and ejaculate traits follow similar patterns. The variation we found does not follow simple latitudinal patterns, suggesting that other forces may be driving sperm and ejaculate trait divergence across sites. We also have data that suggest sexual selection may play a role in driving sperm trait variation, but we caution that additional sites need to be sampled.

Cryopreservation of lar gibbon semen collected by manual stimulation.

We confirmed ejaculation as a result of manual stimulation in a lar gibbon, and attempted to cryopreserve the semen using TES-Tris-egg yolk-based (TTE) extender. After measuring the amount of semen (g), we first diluted the semen with TTE extender, and calculated sperm concentration (sperm/ml), total sperm count (sperm), and progressive sperm motility (%). Then, we cooled diluted semen slowly to 4°C over 2h, and added an equal volume of secondary extender containing glycerol over 30min. Finally, we flash-froze the semen solution by plunging into liquid nitrogen. In addition, we freeze-thawed the solution to determine the recovery rate of the motile sperm. Collection of semen was successful on four of the five occasions. The median (min-max) quantity of ejaculate was 0.19g (0.09-0.26g), the median sperm concentration was 1.38×10(9)sperm/ml (1.20-1.53×10(9)sperm/ml), and the median total sperm count was 0.26×10(9) sperm (0.11-0.40×10(9) sperm). Moreover, the median sperm motility immediately after ejaculation was 65% (60-75%), the median sperm motility after freeze-thawing was 30% (25-35%), and the median recovery rate was 42.3% (40.0-58.3%). We were able to (1) collect semen from a lar gibbon by manual stimulation, (2) reveal andrological findings regarding semen characteristics, and (3) preserve the genetic resource using TTE cryopreservation.

Testicle size as indicator of fertility in bulls

Male calves from the high value parents, bull fathers and bull dams, enter the selection for artificial insemination. After laboratory tests, the calves are taken to the center for artificial insemination, and after a stay in quarantine the are moved to a test station. At the age of twelve months they are measured for assessing the value of each calf exterior. One of the measures recorded was the testicle scope. On the basis of testicle size, it is possible to predict sperm production potential. For the determination of testicle size (testicular biometry), tapes or rulers were used. The aim of this work was to investigate the possible effect of testicle size on sperm production in young bulls used for artificial insemination. For that purpose there were used the data on circumference of testicles of one year old bulls just starting production of sperm, and then compared with certain semen quality parameters such as: volume of ejaculate and concentration and percentage of alive and progressively mobile spermatozoa. The investigation included all young bulls that started production in the period from 2010. to 2012., that is 36 bulls of various breeds (Simmental, Holstein Friesian, Montafon). After the testicle scope measuring in these bulls, there were observed the parameters of the sperm quality during the following one year period. The obtained results showed that the increased testicle size was followed by the increased average ejaculate quantity, in other words: 3.7 ml in group of bulls with testicle circumference below 30 cm, to 6.7 ml in bulls whose testicle circumference was over 40 cm. Also, the results showed that there was a correlation between the increased testicle size and the increased spermatozoa concentration. The values grow to testicle scope of 36 cm, and above that they were still high but with some oscillations. When it came to relation between testicle scope and the percentage of alive and progressively mobile spermatozoa, the trend line showed their positive correlation. The percentage of rejected ejaculates varied from 72% in bulls wit testicle scope below 30 cm to 10% in bulls with testicle scope above 35 cm. On the basis of the results obtained in this work, the conclusion is that testicle size is an indicator of bull fertility; that there is a significant correlation between testicle size and ejaculate volume, and that there is a need to explore a genetic link between testicle size and the fertility of their daughters.

Testosterone rapidly increases ejaculate volume and sperm density in competitively breeding goldfish through an estrogenic membrane receptor mechanism

The social environment can have dramatic influences on reproductive behavior and physiology in many vertebrate species. In males, interactions with conspecifics affect physiological processes that increase an individual's ability to compete for mates. For example, in some species, males rapidly adjust the number of sperm they ejaculate in response to sociosexual cues from male and female conspecifics, however, little is known about the physiological mechanisms mediating this behavior. In goldfish, as in many vertebrates, social cues also drive transient surges of the gonadal hormone testosterone (T), which induces rapid effects on cellular processes via its conversion to estradiol (E2). We asked whether such surges rapidly influence ejaculate quantity and quality by experimentally manipulating peripheral levels of T and E2. We show that male goldfish injected with T increased ejaculate (milt) volume and sperm density within just 1hr. Furthermore, increases in expressible milt were dependent on the conversion of T to E2 by the enzyme aromatase, required activation of estrogen receptors α and β, and were also elicited by BSA-conjugated E2, which acts on cell membrane-bound estrogen receptors. Together, these findings represent a novel steroid mechanism for the social modulation of sperm output over the short time scales that characterize reproductive encounters, and thus demonstrate a previously undescribed functional consequence of rapid estrogen signaling mechanisms. We suggest that such mechanisms may play a critical role in the enhancement of physiological and behavioral processes that increase reproductive success in competitive mating contexts.

The influence of male ejaculate quantity on female fitness: a meta-analysis

Although the primary function of mating is gamete transfer, male ejaculates contain numerous other substances that are produced by accessory glands and transferred to females during mating. Studies with several model organisms have shown that these substances can exert diverse behavioural and physiological effects on females, including altered longevity and reproductive output, yet a comprehensive synthesis across taxa is lacking. Here we use a meta-analytic approach to synthesize quantitatively extensive experimental work examining how male ejaculate quantity affects different components of female fitness. We summarize effect sizes for female fecundity (partial and lifetime) and longevity from 84 studies conducted on 70 arthropod species that yielded a total of 130 comparisons of female fecundity and 61 comparisons of female longevity. In response to greater amounts of ejaculate, arthropod females demonstrate enhanced fecundity (both partial and lifetime) but reduced longevity, particularly for Diptera and Lepidoptera. Across taxa, multiply mated females show particularly large fecundity increases compared to singly mated females, indicating that single matings do not maximize female fitness. This fecundity increase is balanced by a slight negative effect on lifespan, with females that received more ejaculate through polyandrous matings showing greater reductions in lifespan compared with females that have mated repeatedly with the same male. We found no significant effect size differences for either female fecundity or longevity between taxa that transfer sperm packaged into spermatophores compared to taxa that transfer ejaculates containing free sperm. Furthermore, females that received relatively larger or more spermatophores demonstrated greater lifetime fecundity, indicating that these seminal nuptial gifts provide females with a net fitness benefit. These results contribute to our understanding of the evolutionary origin and maintenance of non-sperm ejaculate components, and provide insight into female mate choice and optimal mating patterns.

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.

Genetic benefits enhance the reproductive success of polyandrous females.

Although it is generally accepted that females can gain material benefits by mating with more than one male, the proposal that polyandry provides genetic benefits remains controversial, largely because direct experimental support is lacking. Here, we report the results of a study testing for genetic benefits to polyandry in the pseudoscorpion Cordylochernes scorpioides. In an experiment that controlled for male mating experience and the number of spermatophores accepted by a female, twice-mated females received either one sperm-packet from each of two different males (the "DM" treatment) or two sperm-packets from a single male (the same male or "SM" treatment). Over their lifetime, DM females gave birth to 32% more offspring than did SM females, primarily because of a significantly reduced rate of spontaneous abortion. This result could not be attributed to male infertility nor to lack of sexual receptivity in males paired with previous mates. Spermatophore and sperm numbers did not differ between males presented with a previous mate and males paired with a new female. Because SM and DM females received the same quantity of ejaculate, it was possible to eliminate material benefits as a contributor to the enhanced reproductive success of DM females. The reduction in embryo failure rate achieved by DM females is most consistent with the genetic incompatibility avoidance hypothesis, i.e., that polyandry enables females to exploit postcopulatory mechanisms for reducing the risk and/or cost of fertilization by genetically incompatible sperm. This study, which rigorously controlled for material benefits and excluded inbreeding effects, demonstrates that polyandry provides genetic benefits that significantly enhance female lifetime reproductive success.

Snail sperm production characteristics vary with sperm competition risk

Sperm competition is widespread and influences both male investment in spermatogenic tissue and ejaculate characteristics. Sperm competition models assume trade-offs between sperm size and number, although such trade-offs may be difficult to detect. This study examines the effects of sperm competition risk on the sperm production characteristics of the freshwater snail Viviparus ater. In this prosobranch, females mate frequently and store sperm, generating sperm competition. Males produce two sperm morphs, fertile eupyrene sperm and non-fertilizing oligopyrene sperm. Non-fertilizing sperm may play a role in sperm competition and therefore, like fertilizing sperm, the number produced could vary relative to sperm competition risk. In addition, trade-offs between sperm number and sperm size may be expected. We manipulated the sex ratio of sexually mature snails and found the presence of rivals affected the ratio of oligopyrene/eupyrene sperm males produced. In experimental and natural populations, the number of oligopyrene sperm produced, but not the number of eupyrene sperm, was significantly higher when the sex ratio was male biased. Testis mass did not vary between experimental treatments. We also found a negative relationship between the number and size of oligopyrene sperm produced, which is consistent with evolutionary models of sperm competition, and is, to our knowledge, the first intraspecific demonstration of a trade-off between these traits.

Mating performance of paddock-mated rams. I. Changes in mating performance, ejaculate characteristics and testicular size during the joining period

A series of field experiments was undertaken to examine the possible relationship between the major factors thought to influence the paddock-mating performance of rams (sperm producing capacity, sperm output and mating behaviour) and flock fertility. Also the effect of mating on these factors was examined. Six mating groups were used, four ram groups were subjected to conventional paddock-mating conditions, using paddocks ranging in size from 2.5 to 30 ha and were joined for 6 to 7 weeks to 110 (two rams), 112 (two rams), 204 (three rams) and 336 ewes (six rams) respectively at a rate of 7.6, 10.3, 6.3 and 6.5 g testicular tissue per ewe. Rams of the remaining two groups, of three rams each, were selected for High (High TV) and Low (Low TV) testicular volume and were joined to 152 and 150 ewes each at a rate of 5.5 and 4.1 g testicular tissue per ewe for 16 days, following which they were immediately rejoined with a second group of 140 ewes each for 34 days. In all groups the proportion of ewes mated during the first 17 days was high (87–92%); this level of sexual activity had no apparent adverse effect on the fertility of the rams as reflected by percentage of ewes returning to first service. Semen collections were taken from the Working rams and the Control rams prior to, during and after the joining period. Semen samples were evaluated for the ejaculate quantity parameters of volume, sperm density, and total number of sperm, and for the ejaculate quality parameters of motility score, % live sperm and % morphologically abnormal sperm. For the paddock mated rams, volume, density, and total sperm per ejaculate were high during the pre-joining period with mean values ranging from 0.79–1.10 ml, 3.16 · 10 9–4.25 · 10 9 sperm/ml and 3.59 · 10 9–4.09 · 10 9 sperm respectively. The values decreased to a stable minimum level during the peak mating period with mean values ranging from 0.35–0.49 ml, 0.97 · 10 9–1.29 · 10 9 sperm/ml and 0.37 · 10 9–0.56 · 10 9 sperm respectively, and increased to near pre-joining levels during the latter stages of the joining period. For all mated rams combined, there were no significant relationships between prejoining testicular size and ejaculate quantity characteristics recorded during the joining period. At male to female breeding ratios of 2.0% it does not seem warranted to select for increased testicular size prior to joining. The effects of mating on semen motility, % live sperm and % morphologically abnormal sperm were not as clear cut as those on ejaculate volume or density. Motility score for mated rams followed a pattern similar to that for ejaculate density, but no consistent pattern was observed in the percentages of live or abnormal sperm. The relationships between the characteristics of ejaculates collected during the period of high mating activity and flock fertility were not significant for individual semen characteristics or for all characteristics combined. Incorporating the estimated number of services per ewe did not significantly improve this relationship. Testicular volume and scrotal circumference decreased significantly to 56–86% and 80–92% of pre-joining levels respectively in all the mated ram groups excepting Low TV rams. The rate of decrease was linearly related to pre-joining testicular size of the rams and was not solely attributable to liveweight change. It was concluded that mating had a direct and adverse effect on the testicular size of rams which appears to be accelerated by the sudden decrease in liveweight often experienced by paddock-mated rams.