Decreased Semen Volume Research Articles

Lifestyles Associated With Human Semen Quality: Results From MARHCS Cohort Study in Chongqing, China.

Decline of semen quality in past decades is suggested to be potentially associated with environmental and sociopsychobehavioral factors, but data from population-based cohort studies is limited. The male reproductive health in Chongqing College students (MARHCS) study was established in June 2013 as a perspective cohort study that recruited voluntary male healthy college students from 3 universities in Chongqing. The primary objectives of the MARHCS study are to investigate the associations of male reproductive health in young adults with sociopsychobehavioral factors, as well as changes of environmental exposure due to the relocation from rural campus (in University Town) to metro-campus (in central downtown). A 93-item questionnaire was used to collect sociopsychobehavioral information in manner of interviewer-interviewing, and blood, urine and semen samples were collected at the same time. The study was initiated with 796 healthy young men screened from 872 participants, with a median age of 20. About 81.8% of this population met the WHO 2010 criteria on semen quality given to the 6 routine parameters. Decreases of 12.7%, 19.8%, and 17.0%, and decreases of 7.7%, 17.6%, and 14.7% in total sperm count and sperm concentration, respectively, were found to be associated with the tertiles of accumulated smoking amount. Fried food consumption (1-2 times/wk or ≥3 times/wk vs nonconsumers) was found to be associated with decreased total sperm count (10.2% or 24.5%) and sperm concentration (13.7% or 17.2%), respectively. Coffee consumption was found to be associated with increased progressive and nonprogressive motility of 8.9% or 15.4% for subjects consuming 1-2 cups/wk or ≥3 cups/wk of coffee, respectively. Cola consumption appeared an association with decreased semen volume at 4.1% or 12.5% for 1-2 bottles/wk or ≥3 bottles/wk. A cohort to investigate the effects of environmental/sociopsychobehavioral factors act on semen quality was successfully set up. We found smoking, coffee/cola/fried foods consumption to be significantly associated with semen quality from the baseline investigation.

Sexual behavior and seminal characteristics of fertile mature New Zealand White male rabbits of different body weights

Body weight in different mammalian species influences reproductive potential. The aim of the present study was to determine the relationship of body weight at the time of semen collection with libido, seminal characteristics and number of semen doses for artificial insemination (AI) in New Zealand White mature fertile male rabbits. Data came from 728 semen collections of 14 rabbits, 15-months of age that were sexually experienced with proven semen quality and fertility. Semen collection was performed twice a week with two ejaculates at each collection time and lasted 14 weeks. A second ejaculation was collected at 1–2h after the first. Data from each male from first and second ejaculates from 1 day of semen collection throughout the trial were averaged (n=324) and partial correlation coefficients and regression equations were estimated to describe the relationship of male body weight to ejaculation reaction time and 12 semen and sperm characteristics. As body weight increased there was a linear (P<0.05) increase in reaction time, abnormal sperm with an intact membrane and abnormal sperm with a damaged membrane and a linear (P<0.05) decrease in semen volume, sperm concentration per ejaculate, normal sperm with an intact membrane, number of normal motile sperm with an intact membrane and suitable semen doses for AI. Body weight of the mature male rabbit at semen collection had some influence on libido, semen and sperm characteristics, with a general trend toward a lesser reproduction potential as body weight increases.

Increased pregnancy after reduced male abstinence

This study was conducted to test the hypothesis that continuous epididymal sperm depletion after recurrent ejaculations (REC) in contrast to a period of abstinence (ABS) results in a decreased level of sperm DNA fragmentation (SDF) and a consequent increased rate of pregnancy. Forty couples undergoing intra-cytoplasmic injection (ICSI) were asked to abstain from ejaculation for a period of 4 days and then ejaculate once per day for a period of 4 days, followed by a period of abstinence for 12 hours; sperm samples obtained after ABS and REC were assessed for volume, concentration, motility, and SDF and compared in 25 of the patients. Additionally, and in a different experiment, the pregnancy rate of this experimental group (40 couples) was compared to a control group of 150 couples in which the males had abstained from ejaculation for 4 days prior to ejaculation. Sperm selection was performed using density gradient centrifugation prior to ICSI. Semen quality in the REC group that was assessed over the course of the ejaculation schedule showed a decrease in semen volume (67%) and SDF (27%) following sperm selection; there was no difference for sperm motility or sperm concentration. When the pregnancy rate between the 40 couples in the REC group and 150 couples in the control ABS group were compared, the REC group had a pregnancy rate of 56.4% (25/40), whereas the ABS rate was only 43.3% (65/150) (p = 0.030). We conclude that recurrent ejaculation every 24 hours for four days with a final abstinence of 12 hours, combined with sperm selection using density gradient centrifugation, produces a significant increase in pregnancy rate when using ICSI. As ICSI was the strategy selected for fertilization, we propose that the observed reduction in SDF was the primary factor leading to improved reproductive outcome.

Semen Quality and Sperm Function Loss by Hypercholesterolemic Diet Was Recovered by Addition of Olive Oil to Diet in Rabbit

Fat increment (0.05% cholesterol, chol) in standard diet promoted a significant increase in serum and sperm membrane chol, which ultimately altered membrane-coupled sperm specific functions: osmotic resistance, acrosomal reaction, and sperm capacitation in White New Zealand rabbits. These changes were also associated with a reduction in motility percentage and appearance of abnormal sperm morphology. The present study was carried out to evaluate the effect of dietary olive oil (OO, 7% v/w) administration to several male hypercholesterolemic rabbits (hypercholesterolemic rabbits, HCR) with altered fertility parameters. These HCR males were achieved by feeding normal rabbits with a high-fat diet (0.05% chol). HCR were associated with a modest non-significant increase in body weight (standard diet, 4.08±0.17 Kg, versus high-fat diet, 4.37±0.24 Kg). Hypercholesterolemic rabbits presented a marked decrease in semen volume, sperm cell count, and percentage of sperm motility, associated with a significant increase in sperm cell abnormalities. Moreover, sperm capacitation measured by the characteristic phosphorylated protein pattern in and induced acrosomal reaction were also altered suggesting sperm dysfunction. However, the administration of OO (for 16 weeks) to rabbits that were fed with 50% of the high-fat diet normalized serum chol. Curiously, OO supply succeeded to attenuate the seminal and sperm alterations observed in HCR group. Administration of OO alone did not cause any significant changes in above mentioned parameters. These data suggest that OO administration to HCR male rabbits recovers the loss of semen quality and sperm functionality.

Association between a biomarker of exposure to polycyclic aromatic hydrocarbons and semen quality

Growing evidence supports the reproductive and developmental toxicity of polycyclic aromatic hydrocarbons (PAHs) from prenatal and postnatal exposure, but the results of epidemiological studies regarding harmful effects of PAHs exposure on male reproductive system still remain limited and inconclusive. The aim of the present study was to investigate the relationship between 1-hydroxypyrene, a biomarker of polycyclic aromatic hydrocarbons exposure and semen quality. The study population consisted of 277 men attending an infertility clinic for diagnostic purposes and having normal semen concentration of 20-300 mln/ml or slight oligozoospermia (semen concentration: 15-20 mln/ml) (WHO 1999). All the men were healthy and under 45 years of age. All participants were interviewed and provided a semen sample. The interview included questions concerning demographics, socio-economic status, medical history related to past diseases which may have an impact on semen quality, lifestyle factors and occupational information. Concentrations of 1-hydroxypyrene (1-OHP) in the urine samples were analyzed using high performance liquid chromatography (HPLC). A positive association was found between the level of 1-OHP in urine and sperm neck abnormalities as well as the percentage of static sperm cells (p = 0.001, p = 0.018, respectively). Additionally, exposure to PAHs measured by 1-OHP in urine decreased semen volume and the percentage of motile sperm cells (p = 0.014, p = 0.0001, respectively). Presented findings indicate that the environmental level of PAHs exposure adversely affects male semen quality. The future large-scale studies should incorporate different biomarkers to generate a more accurate and full assessment of the effects of PAHs exposure on male fertility.

Prostate Effect in Dogs with the Aldosterone Receptor Blocker Eplerenone

Eplerenone (Inspra) is an aldosterone receptor antagonist approved for the treatment of hypertension and heart failure after a myocardial infarction. In vitro receptor binding and transactivation studies showed eplerenone had high selectivity for the mineralocorticoid receptor over other steroid receptors (glucocorticoid, androgen, and progesterone). The most sensitive off-target effect of orally administered eplerenone preclinically was prostate atrophy in dogs. Dose-related prostate atrophy was observed at eplerenone dosages ≥15 mg/kg/day for 13 weeks or longer. The no observed adverse effect level (NOAEL) for the prostate effect in dogs was 5 mg/kg/day. The maximal effect was seen by 13 weeks and the atrophy was reversible even after 1 year of daily treatment. An additional study demonstrated dogs with eplerenone-induced prostate atrophy (confirmed by intrarectal ultrasound) had slightly decreased semen volume but no compound-related effects on libido, semen protein content, sperm motility, daily sperm production, or epididymal sperm transit time. Four possible mechanisms for prostate effect were investigated: (1) inhibition of testosterone synthesis and secretion; (2) inhibition of 5α-reductase, the enzyme within the prostate that converts testosterone into the more active growth factor dihydrotestosterone (DHT); (3) competitive antagonism of the androgen receptor; and (4) inhibition of 5α-reductase or competitive antagonism of the androgen receptor by aldosterone, which increased in dogs treated with eplerenone. Data from these studies supported blockade of androgen receptors at suprapharmacological concentrations of eplerenone. Another mineralocorticoid blocker, spironolactone, had greater antiandrogenic activity than eplerenone both in vivo and in vitro, and it has well known clinically significant antiandrogenic effects in humans, whereas eplerenone does not.

Imaging Diagnosis, Transurethral Endoscopic Observation, and Management of 43 Cases of Persistent and Refractory Hematospermia

The goal of this study was to explore minimally invasive transurethral imaging and surgery for the treatment of severe, persistent hematospermia in cases that were refractory to conservative treatments. The study included 43 patients (aged 22-77 years; average, 44.6 years) with long-lasting, severe hematospermia, accompanied by discomfort or pain in the lumbosacral or perineal region, dysuria, frequent micturition, decreased semen volume, and/or azoospermia. Patient symptoms had persisted for 1 to 10 years (average, 5.3 years). Computed tomography or magnetic resonance imaging of each patient was evaluated, and transurethral surgery was performed. The causes of hematospermia were identified in all 43 patients, and their ejaculatory duct obstruction or seminal vesiculitis was successfully treated. No serious intraoperative or postoperative complications occurred. Pathologic analyses revealed that all of the resected or biopsied seminal vesicle tissues had chronic nonspecific inflammation in the seminal vesicle wall, and no tumors were identified. Preoperative symptomology of hematospermia disappeared in all patients followed up for 2 to 30 months (average, 16 months). A single patient experienced recurrence at 11 months and had a second minimally invasive surgery that was curative. A total of 95.3% (41 of 43) of the patients experienced normal orgasmic intensity after surgery. Magnetic resonance imaging is a valuable and accurate diagnostic method for the identification of causative factors underlying hematospermia. Transurethral dilation of ejaculatory ducts, incision of the verumontanum or the distal end of the ejaculatory ducts, and incision or resection of the relevant cysts represent simple, safe, and reliable approaches for the management of refractory cases of hematospermia that do not respond to conservative treatments.

Severe oligozoospermia in a patient with myxedema coma

A case of severe oligozoospermia with myxedema coma is herein presented. The patient was referred to a male infertility clinic with a 5-year history of primary infertility. Decreased serum testosterone and elevated serum prolactin without abnormal MRI findings in the hypothalamus, and decreased semen volume and sperm motility were noted. A GnRH test revealed a decreased luteinizing hormone response, whereas the HCG test showed a normal testosterone increase. Because a urinalysis after ejaculation indicated retrograde ejaculation, imipramine administration was started. However, the semen quality deteriorated, so the patient was referred to an ART clinic. Twenty-one months from the initial visit, the patient developed a loss of consciousness and edema due to myxedema coma, a life-threatening state of hypothyroidism. The patient recovered after 1 month of thyroid hormone replacement therapy (HRT) with corticosteroids. Three months after the myxedema coma, a semen analysis showed a decreased semen volume (0.2 mL) and severe oligozoospermia (two spermatozoa/ejaculate). Elevated prolactin and decreased testosterone levels were still present. These parameters gradually improved after restoration of euthyroidism by HRT. In conclusion, physicians should confirm the thyroid function in the management of male infertility, especially in patients with elevated prolactin levels.

Quality of 4-hourly ejaculates - levels of calcium and magnesium

A four-hourly ejaculation study was conducted in which eleven normal healthy subjects participated. Five of them discontinued after submitting three samples. One alone was present for submission at the end of 16h (fifth ejaculate), which was his last submission. Physical exhaustion was the sole reason for all participants for their discontinuation from the study. The result showed a decrease in semen volume and sperm count from first to last ejaculate. The increase in motility was probably due to reduction in exposure time to sperm motility inhibitory factors. In general, total motile spermatozoa as well as actively motile spermatozoa progressively increased from first to last ejaculate at the cost of sluggish spermatozoa. A significant increase in seminal plasma calcium and magnesium was seen as well as a significant increase in magnesium inside the cell from the first to the fourth ejaculate. Considering the quality of semen, which was good in sperm count and excellent in motility, calcium and magnesium may be helpful in cleaning motility inhibitory factors of spermatozoa.

Semen and hormonal parameters in men with chronic hepatitis C infection

Male patients with chronic hepatitis C virus (HCV) infection (n = 57) demonstrated a statistically significant decrease in semen volume, sperm count, and progressive sperm motility and a statistically significant increase in abnormal sperm morphology compared with healthy controls (n = 40). The duration of the HCV infection was negatively correlated with semen volume and sperm motility where the HCV RNA viral load was negatively correlated with sperm count and sperm motility. Chronic HCV patients had statistically significantly lower total serum testosterone and higher serum E(2) and prolactin levels compared with healthy controls.

The effects of vasectomy on viscosity, pH and volume of semen in man.

The effects of vasectomy on seminal viscosity, volume and pH have been investigated in freshly emitted semen of 21 healthy men before operation and three months later. Viscosity and the pH range were decreased significantly, but the decrease of the seminal volume was not significant. Reasons of changes have been discussed.

Decreased Semen Volume and Spermatozoa Motility in HIV‐1‐Infected Patients Under Antiretroviral Treatment

Inconsistent results have been reported for the semen quality in HIV-infected men, due to the biases inherent in some studies. The objective of the present study was to investigate the semen parameters in HIV-1-infected patients and to compare their sperm characteristics with those of a control group of fertile, noninfected men. Factors implicated in semen alterations in HIV-1 patients were also analyzed. HIV-infected men (n=190), of whom 91% were undergoing antiretroviral therapy, and 218 fertile men were studied. Infertility risk factors were recorded and clinical examinations were performed for both groups. Records of history of HIV infection, antiretroviral treatment, and HIV-1 RNA detection in the blood as well as HIV-1 genome detection in the semen were obtained for the infected patients. Semen volumes, percentages of progressive motile spermatozoa, total sperm counts, and polymorphonuclear cell counts were decreased, while the pH values and spermatozoa multiple anomaly indices were increased in HIV-infected patients. Even after adjustment for possible sources of bias, the decreases in semen volume and progressive motility and the increase in pH remained significant. The present study demonstrates sperm motility and ejaculate volume alterations in HIV-1-infected patients, most of whom were receiving antiretroviral therapy. In HIV-1 patients, further longitudinal studies are required to analyze the impact of treatment regimen on sperm parameter alterations.

Semen quality in a population of volunteers from the province of Barcelona

A prospective study was carried out on 1005 male volunteers residing in the province of Barcelona. Participants were asked to complete a questionnaire concerning their health status and lifestyle, and provided a semen sample for analysis. Sperm concentration and percentages of motile, and normal forms were evaluated. The effect of smoking, alcohol consumption, stress and previous disease on semen parameters was also evaluated. Normal parameters were found in 22% of volunteers and sperm counts and/or percentage motility below normal threshold values were found in 78%. Asthenozoospermia was detected in 62% and oligozoospermia in 17% of volunteers. No statistically significant association was found between semen quality and age, with the exception of a decrease in semen volume (P = 0.04) and progressive motility (P = 0.01). No statistically significant differences in semen parameters were found between smokers and non-smokers or between males who consumed alcohol versus those that did not. However, stress had a negative effect on sperm concentration. In conclusion, the prevalence of normal semen parameters in the study population evaluated was markedly lower than that reported for the general population (60–70%). Since sperm concentration did not appear to decrease with age, the decrease observed in the last decades may be related to exposure to environmental toxicants during the fetal period, as previously suggested.

Androgen receptor gene GGN repeat length and reproductive characteristics in young Swedish men

The human androgen receptor (AR) gene contains two polymorphisms of CAG and GGN repeats respectively. The GGN repeat function is still largely unknown and to date there are no in vivo data on this segment with respect to the general population. We investigated the impact of CAG and GGN repeats on male reproductive function, one by one and in interaction with each other, in 220 adolescent men from the general Swedish population. Physical examination and semen analysis, including accessory sex gland markers and measurement of reproductive hormone levels, were performed. Lifestyle-associated factors, including maternal smoking during pregnancy, were recorded. GGN and CAG repeat lengths were determined by sequencing. GGN<23 was associated with lower semen volume when compared to GGN=23 (mean difference -0.6 ml, P=0.02) and GGN>23 (mean difference -0.9 ml, P=0.002). Men with GGN<23, exposed to maternal smoking during pregnancy, had higher body mass index compared to men with other GGN lengths, no matter whether their mother had smoked or not during pregnancy (mean difference 4.8 kg/m2, P<0.001). Short GGN repeats seem to be associated with decreased semen volume, possibly due to suboptimal AR activity. Body composition may be influenced by the combination of fetal exposure to maternal smoking and certain AR genotypes.

Cigarette smoking is related to a decrease in semen volume in a population of fertile men

To evaluate the semen quality and hormonal levels in fertile men according to their level of cigarette smoking. We evaluated 889 fertile men who came for a vasectomy for sterilization purposes. The men included 522 non-smokers, 143 mild smokers (<10 cigarettes/day), 154 moderate smokers (11-20/day), and 70 heavy smokers (>20/day). We evaluated sperm concentration, motility, motion variables and hormonal levels in these men. There were no significant differences among the groups in sperm concentration or motility, or in levels of follicle-stimulating hormone, luteinizing hormone, or serum total testosterone. Also, sperm motion characteristics did not differ across the groups. Semen volume was the only semen variable which tended to decrease according to the number of cigarettes smoked. Cigarette smoking had no apparent effect on sperm concentration, motility or reproductive hormonal levels, but tended to reduce semen volume.

Cigarette smoking is related to a decrease in semen volume in a population of fertile men

Cigarette smoking is very common despite worldwide anti-smoking campaigns. It is considered as one of the causes of sub-fertility in males. It may result in decreased sperm concentration, poor motility and morphology, and high rates of sperm with DNA damage. However, even though many studies have shown the association of cigarette smoking with reduced semen quality in men diagnosed with infertility, however, studies evaluating the impact of smoking on the semen quality of normal fertile men are lacking. The goal of our study was to evaluate the semen quality and hormonal levels in mild, moderate, heavy and nonsmokers fertile men undergoing vasectomy for sterilization purposes. Retrospective study at a tertiary care institution. University based center. The Institutional Review Board approved the study and all the patients provided informed consent. 889 vasectomies for voluntary sterilization purposes were performed from January 1999 to March 2003. Computer-assisted semen analysis was performed on all specimens, with a Motion Analysis (VP 50) semen analyzer. We divided the patients into four groups: non-smokers (Group A; n = 522), mild smokers (Group B, < − 10 cigarettes/day; n = 143), moderate smokers (Group C, − 11–20 cigarettes/day; n = 154), and heavy smokers (Group D, > − 20 cigarettes/day; n = 70). We evaluated sperm concentration, motility, motion parameters, and hormonal levels in these men at the time of their visit. Data was evaluated with ANOVA. No differences were seen across Groups A to D in sperm concentration (109.18 ± 76.21, 107.49 ± 86.62, 124.51 ± 87.3, and 118.41 ± 85.21; P = 0.071), motility (60.35 ± 15.67, 59.8 ± 15.79, 60.82 ± 14.42, and 53.9 ± 13.18; P = 0.678), follicle-stimulating hormone (3.67 ± 2.10, 4.021 ± 2.10, 3.40 ± 2.4, and 3.53 ± 1.57; P = 0.562), luteinizing hormone (3.32 ± 1.6, 3.66 ± 4.02, 3.03 ± 1.57, and 2.63 ± 1.17; P = 0.213), and serum total testosterone (558.59 ± 178.4, 595.26 ± 175.33, 561.23 ± 166.62, and 659.92 ± 212.67; P = 0.266). Also, sperm motion characteristics did not differ across the groups: curvilinear velocity (71.99 ± 16.44, 71.008 ± 16.37, 72.81 ± 14.41, and 70.2 ± 13.38; P = 0.828), linear velocity (40.58 ± 10.33, 39.43 ± 10.72, 39.60 ± 9.752, and 38.85 ± 7.50; P = 0.796), linearity (55.72 ± 7.86, 54.82 ± 8.73, 53.4 ± 9.16, and 54.63 ± 8.38; P = 0.211), lateral head displacement (3.03 ± 0.92, 3.1 ± 0.88, 3.28 ± 0.99, and 3.001 ± 0.94; P = 0.473), and beat cross frequency (23.79 ± 6.48, 24.01 ± 4.96, 23.47 ± 7.28, and 21.74 ± 7.96; P = 0.499). Semen volume was the only semen parameter, which tends to decrease according to the number of cigarettes smoked (2.82 ± 1.44, 2.42 ± 1.403, 2.30 ± 1.151, and 2.08 ± 0.82; P = 0.004). Semen volume tends to decrease according to the number of cigarettes smoked. A decrease in semen volume may be the first sign of semen quality impairment in cigarette smokers even before a decline in sperm concentration, percent sperm motility and normal sperm morphology.

Effect of changing female stimulus on intensive semen collection in young Murciano-granadina male goats.

The aim of this research was to study the effect of changing female stimulus on libido and semen characteristics from young Murciano-granadina male goats submitted to intensive semen collection using females not in estrus as teasers. Males were submitted to two different sexual stimulation procedures. In the first procedure, the same doe was used as the female stimulus for three consecutive presentations. In the second, the doe was replaced after the second presentation by a new female. Semen volume, concentration, forward progressive motility, and live spermatozoa were scored. To analyze reaction time (RT), three types of analysis were performed. In the first one, RT was analyzed by multifactor ANOVA, taking as a missing value 300 s when a buck did not ejaculate. In the second, RT also was analyzed by multifactor ANOVA, but data from males that did not ejaculate were removed. In the third, a Cox Survival analysis was carried out by censoring data when a buck did not ejaculate within 5 min of entering the test arena. A decrease in semen volume and sperm concentration in the successive ejaculations was observed, being highly marked in the third ejaculation independent of the stimulation procedure (0.62 vs. 0.38 and 0.43 mL, and 2,828 vs. 2,183 and 2,223 million spermatozoa/mL to the first and third ejaculation respectively; P < 0.05). No significant differences were observed either in forward progressive motility or live sperm rate. Changing the female stimulus in the third presentation had no significant effect on any seminal characteristic. Regarding libido and mounting behavior variables, there was a substantial decrease in RT in the third service when the female was changed (with both types of ANOVA). When censored data were taken into account, the relative risk showed that the probability of a male ejaculating in the third presentation increased almost fourfold when the female was replaced than when the female was the same in all services (P < 0.05). In conclusion, young Murciano-granadina bucks can be used as semen donors because none of the most important semen variables used to reject or accept an ejaculate before freezing process decreased after intensive semen collection. We also recommend changing the female stimulus to make the semen collection procedure more efficient and using survival analysis methodology to analyze time data, mainly when a high rate of censored data are scored.

Aging and infertility in women: a committee opinion

Aging and infertility in women: a committee opinion

Secular sperm trends in stallions between 1981 and 1996.

Several reports have suggested that human semen quality has declined throughout the world over the last few decades. Chemicals in the environment acting as endocrine disrupters have been implicated as a possible cause. If this is indeed the case, then similar effects may be observed in animals. We analyzed 1489 ejaculates collected from 390 Breton draught stallions between 1981 and 1996. Semen was collected from all the stallions at a single center, according to standardized semen collection protocols and laboratory methods. Semen volume decreased slightly but significantly and there was an increase in sperm concentration over the study period. However, total sperm production was unchanged. Seminal fluid volume is controlled by accessory sex glands, which are regulated by androgens. Chemicals with antiandrogenic properties have been detected in the environment. By affecting the development or function of accessory sex glands, these chemicals may be at least partly responsible for the observed decrease in semen volume.

Biochemical properties and usefulness of boar semen for liquid preservation following atropine administration.

Four sexually mature boars were used in two different experiments. In Experiment I, two boars were injected once subcutaneously with atropine and, ejaculates were collected after 30, 60 and 90 min. In Experiment II, each boar was injected weekly with 25, 37.5 and 50 mg of atropine, and ejaculates were collected after 30 min. Ejaculates obtained in Exp. II were diluted with Kortowo-3 extender (Olsztyn, Poland), with and without the addition of low density lipoprotein fraction (LDF) isolated from hen egg yolk,and stored at 5 degrees C and 16 degrees C for 5-6 days. Atropine caused a decrease in semen volume and an increase in sperm concentration with fewer agglutinated spermatozoa. Changes in sperm motility were not significant. There was a significant increase in the content of fructose, zinc, citric acid and protein in the seminal plasma of atropine-injected boars. Furthermore, increased antiproteolytic and antiperoxidant activity as well as seminal phosphatases were also observed. No significant changes were observed in the content of free sialic acid, whereas bound sialic acid was significantly increased in Exp. II. A decrease in osmolality and pH of seminal plasma was observed. Electrophoretic studies revealed that there were alterations in the molecular forms of seminal phosphatases and proteinase inhibitors. There were no significant changes in the percentage of morphologically abnormal spermatozoa, osmotic plasmalemma resistance at the acrosomal region (ORT) and malondialdehyde production in the spermatozoa. AspAT activity recovered from cold shocked spermatozoa was significantly reduced, whereas disturbances in plasma membrane permeability to fluorochrome HO 258 were observed in Exp. I. Semen of atropine-injected boars had increased sperm viability during liquid preservation at 5 and 16 degrees C.