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)     

Seasonal analysis of semen characteristics,serum testosterone and fecal androgens in the ocelot (Leopardus pardalis), margay (L. wiedii) and tigrina (L. tigrinus)

Captive adult male ocelots (Leopardus pardalis, n = 3), margays (L. wiedii, n = 3) and tigrinas (L. tigrinus, n = 4) in two locations in southern Brazil were studied for 14 consecutive months to evaluate the effect of season on testicular function. Reproductive evaluations, including testicular measurements, electroejaculation and blood collection were conducted monthly. Fecal samples were collected weekly for androgen metabolite analysis to assess testicular steroidogenic activity. Ocelots had the highest number of motile spermatozoa in the ejaculate (114.7+/-15.8 x 10(6); P < 0.05), the highest percentage of morphologically normal spermatozoa (82.4+/-1.2%; P < 0.05) and the highest concentration of fecal androgens (1.71 vs. 0.14 microg/g; P < 0.05). Margays and tigrinas had lower numbers of motile spermatozoa (23.4+/-2.8 x 10(6), 74.2+/-8.9 x 10(6), respectively), lower percentages of morphologically normal spermatozoa (57.4+/-2.8, 59.2+/-3.5%, respectively), and lower fecal androgen concentrations (0.15+/-0.01, 0.23+/-0.01 microg/g, respectively). Serum testosterone concentrations were similar among the three species. Fecal androgen concentrations were not affected by season, with the exception of the ocelot where concentrations were higher (P < 0.05) in the summer. Ejaculates were collected throughout the year; however, peaks in average sperm production were observed during the summer for all species. In summary, this study has identified several species differences in male testicular traits among ocelots, margays and tigrinas. Results of longitudinal reproductive assessments suggest males of each species are capable of breeding throughout the year.     

Sexual development of dairy bulls in the Mexican tropics

Sexual development and pubertal traits were studied in Holstein Frisian (Ho) and Brown Swiss (BS) bulls born and maintained under tropical conditions. Characteristics evaluated every 2 weeks, from 27 to 63 weeks of age, included live weight, scrotal circumference, testicular diameter, semen quality and sexual behavior. Puberty was defined as the age at which a bull first produced an ejaculate containing at least 50 x 106 spermatozoa, with a minimum of 10% progressive motility. Testicular growth was linear in Ho bulls and quadratic in BS bulls. There was no breed difference in age at puberty (Ho, 333 +/- 15.8 days; BS, 311 +/- 10.5 days). However, at puberty, live weight and scrotal circumference tended to be greater in Ho (276 +/- 16.9 kg and 28.4 +/- 1 cm, respectively) than in BS bulls (233 +/- 11.3 kg and 25.9 +/- 0.7 cm, respectively), and testicular diameter was larger for Ho (5.5 +/- 0.24 cm) than for BS bulls (4.8 +/- 0.16 cm). Pooled data for all bulls for semen characteristics at puberty were: volume, 6.3 +/- 0.6 ml; progressive motility, 26.8 +/- 4.4%; sperm concentration, 58.5 +/- 13.9 x 10(6) spermatozoa/ml, and 351.5 +/- 91.2 x 10(6) spermatozoa/ejaculate. These values improved until at least 18 weeks after puberty. Eighty-five percent of bulls mounted heifers by 206 days of age, but only a few bulls had mounts with ejaculation during the study. It was concluded that reproductive development was similar between Ho and BS bulls, but slower than that reported for dairy bulls in temperate areas. Variation in some characteristics, such as scrotal circumference, was observed among bulls within each breed group, which might be of benefit for genetic selection.     

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.     

Comparison of seminal quality in Holstein bulls as yearlings and as mature sires

Semen quality was compared in 5 Holstein bulls from samples collected as young sires (yearlings) and again as mature bulls after a mean interval of 1,265 d. At both sampling periods, the semen was examined for ejaculate volume, sperm numbers, post-thaw progressive motility and sperm viability. Sperm viability was assessed on cryopreserved samples with fluorescent SYBR-14 to stain living spermatozoa and propidium iodide (PI) to identify dead spermatozoa. The fluorescent populations of stained spermatozoa were quantified by flow cytometry. The percentages of living spermatozoa for the individual bulls, as determined by green fluorescence of SYBR-14, ranged from 44 +/- 3.1 to 54 +/- 0.3 for yearlings, and from 38 +/- 1.5 to 55 +/- 1.0 for mature sires. No differences in sperm viability were found between samples taken from yearling bulls and those of mature bulls. The percentage of spermatozoa stained with SYBR-14 was negatively correlated (r = -0.97; P = 0.0001) with the percentage of dead spermatozoa as indicated by PI staining. Comparisons of identical samples run on 2 different flow cytometers indicated that either flow instrument could be used to assess sperm viability. Although the individual bulls differed (P < 0.05) in ejaculate volume and sperm numbers as yearlings, they did not differ in these parameters as mature bulls. The average number of spermatozoa per ejaculate changed as a result of maturation, increasing from 6.2 +/- 1.0 to 10.7 +/- 1.1 x 10(9). Aging was significantly correlated with ejaculate volume (r = 0.76; P = 0.01) but not with the total number of spermatozoa per ejaculate (r = 0.51; P = 0.13). The maturational changes that occurred in the 5 bulls were minimal with the exception of the increased volume of the ejaculate and the number of spermatozoa per ejaculate.     

Influence of ejaculation frequency of stallions on characteristics of semen and output of spermatozoa.

Approximately 1 week was required to stabilize the extragonadal sperm reserves in stallions ejaculated daily for 10 weeks. The true daily sperm output of a stallion was equal to the mean daily sperm output of seven ejaculates +/- 1-35 X 10(9) spermatozoa. Mean concentrations of spermatozoa/ml and number of spermatozoa/ejaculate were higher (P less than 0-01) for X1 and X3/week ejaculation frequencies than for a X6/week frequency. Sperm output/week was nearly identical for a X6/week frequency. Sperm output/week was nearly identical for the X3 and X6 frequencies and higher (P less than 0-01) than the X1 frequency. Increase of ejaculation frequency from one to two ejaculates/day twice weekly significantly (P less than 0-01) raised the output of spermatozoa/week. Gel-free semen volume, spermatozoa/ml, and number of spermatozoa/ejaculate were higher (P less than 0-01) in the first, than in the second, ejaculate. Collection of semen on alternate days would be a practical ejaculation frequency for inseminating mares. Two ejaculates collected twice a week would be a practical ejaculation frequency for long-term storage of stallion semen.     

Frequent semen collection and sperm reserves of the male Angora goat (Capra hircus).

Semen was collected from six mature and sexually rested Angora bucks at one-hour intervals five times a day on each of 5 consecutive days in the breeding season. There was a marked decline in semen volume (P less than 0.001), sperm concentration (P less than 0.05) and number of spermatozoa (P less than 0.001) on consecutive days. Successive ejaculates within days differed only in number of spermatozoa (P less than 0.001). The following year at the beginning of the breeding season, the weights of testes and epididymides and the reserves of spermatozoa in these parts were examined after slaughter of the six bucks. The mean number of spermatozoa in the paired testes, capita, corpora and caudae of the epididymides were (22.8 +/- 1.24) x 10(9), (9.4 +/- 1.19) x 10(9), (3.4 +/- 0.22) x 10(9) and (35.0 +/- 2.21) x 10(9), respectively. Epididymal reserves of spermatozoa were correlated with testicular weight (r = 0.50, P = 0.01) and number of spermatozoa in the testes (r = 0.42, P = 0.07), but not with epididymal weight. The daily production of spermatozoa per animal in the breeding season was estimated to be 4.0-6.4 x 10(9).     

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.     

Reproduction of French Angora rabbits: ovulation in the female, semen production in the male]

Ovulation rate and semen quality in French Angora rabbits were investigated to determine the potential of improving breeding practices in this breed. The proportion of does ovulating and their ovulation rate were studied in 40 females, as well as sexual behaviour and semen quality in 8 males. The experiments took place in autumn 1987 and were repeated in winter. Three groups of does were injected with 25, 50 IU hCG or 0.8 microgram GnRH (groups 1, 2 and 3, respectively). Another group was mated and served as a control (group 4). Hormonal treatments improved the proportion of does which ovulated (95, 90, 74 and 28% in groups 1-4, respectively; P less than 0.05) but did not change their ovulation rate (10.9 +/- 0.7, 10.7 +/- 0.7, 11.3 +/- 0.8 and 8.9 +/- 1.3 corpora lutea per ovulating female, groups 1-4, respectively; m +/- SEM, NS). In males, two ejaculates were collected twice weekly for 3.5 weeks from 8 bucks. Ejaculates obtained in March were better than those collected in November (volume: 0.33 vs 0.23 ml, P less than 0.01; raw motility: 5.2 vs 3.9, P less than 0.01; individual motility: 2.7 vs 2.1, P less than 0.05; number of living spermatozoa per ejaculate: 71 vs 28 x 10(6), P less than 0.01, respectively). These results suggest that artificial insemination may be utilized to improve reproductive performance in French Angora rabbits.     

Reproductive parameters of miniature stallions

Breeding soundness evaluation (BSE) of stallions is a routine component of stud farm practice. Guidelines for assessing satisfactory breeding potential have been developed using data derived from stallions of full-size breeds. In view of the increasing popularity of miniature stallions, knowledge of normal semen parameters of these stallions is important. Therefore, testicular measurements and semen parameters from 216 sexually rested miniature stallions were obtained. Semen was collected twice, 1.5 to 3 h apart, using an artificial vagina. Values were averaged over the 2 collections because of the sexual inexperience of the stallions. The smaller stallions (Group A, 72 to 86 cm; Group B, 87 to 96 cm) had smaller testicles (P<0.05), and Group A stallions had the lowest ejaculate volume (P<0.05) compared with Group C (97 to 104 cm) stallions. Thus, although there was no difference in the concentration of spermatozoa per milliliter between groups of stallions, Group A stallions had fewer total spermatozoa in their ejaculate than Group C stallions (4.31+/-0.47x10(9) vs. 5.41+/-0.30x10(9), P<0.05). Moreover, miniature stallions had smaller testicles and fewer total spermatozoa in their ejaculate than is commonly accepted as normal in full-size stallions. Average total scrotal width of miniature stallions was found to be 7.13, 7.38 and 7.95 cm for Groups A, B and C, respectively. The average total number of spermatozoa in the ejaculates of miniature stallions in this study was 4.94+/-0.22x10(9) cells, with 1.75+/-0.09x10(9) total normal, motile spermatozoa. When only stallions <96.5 cm in height were considered (conforming to requirements of the American Miniature Horse Association Registry), the average total number of spermatozoa in the ejaculates was 4.59+/-0.30x10(9) cells, with 1.70+/-0.11x 10(9) total normal, motile spermatozoa. Based on these findings, different criteria should be used to evaluate the potential breeding soundness of miniature stallions than are commonly applied to full-size stallions.     

Epididymal maturation affects calcium regulation in equine spermatozoa exposed to heparin and glucose

Spermatozoal function is affected by the ability to regulate intracellular calcium concentrations ([Ca2+]i), and may be influenced by epididymal maturation as well as environmental components. Regulation of [Ca2+]i in ejaculated and epididymal stallion spermatozoa was monitored over time in various media. Spermatozoa from each of 5 pony stallions (3 ejaculate samples and 1 caput and cauda sample) were labeled with the fluorescent calcium indicator probe Indo-1 in a calcium-free modified Tyrode's buffer. Fluorescent emissions were monitored by a dual wavelength spectrofluorometer over 5 h. Calcium (1 mM) was added at T = 15 min, and heparin (HEP; 10 micrograms/ml) or heparin plus glucose (hGLUC; 5 mM in 10 micrograms/ml heparin) was added at T = 30 min. Spermatozoal Ca2+ content and regulation differed among males (P = 0.0066). Relative initial [Ca2+]i differed significantly among all stages of maturity (0.84 +/- 0.104, 0.76 +/- 0.023, 1.20 +/- 0.036 LSM of relative Ca2+ units for caput, cauda and ejaculate spermatozoa respectively; P = 0.001). Rate of Ca2+ uptake was similar for ejaculate and cauda spermatozoa (0.021 +/- 0.005 and 0.026 +/- 0.002 relative Ca2+ units/sec) but slower for caput spermatozoa (0.012 +/- 0.001; P = 0.0006). There was no immediate effect of HEP or hGLUC in any stage (P > 0.05), and caput spermatozoa did not differ from cauda spermatozoa for any treatment or time period. A significant increase in [Ca2+]i was seen in ejaculate spermatozoa treated with HEP from 2 h on (P < 0.05). This study demonstrates that both the absolute Ca2+ concentration and the rate of Ca2+ internalization in equine spermatozoa is dependent on the stage of maturation. Ejaculate spermatozoa respond to heparin through increased [Ca2+]i, which may play a role in the fertilizing ability of ejaculate spermatozoa.     

Development of macroscopic and microscopic characteristics of ejaculates from Chios, Serres and Karaguniki breed lambs

The developmental characteristics in the volume of the ejaculate, motility (percentage of motile spermatozoa) and grade of motility (vitality), density, total number of spermatozoa per ejaculate and percentage of dead (stained) and of morphologically abnormal spermatozoa were studied in 14-to 46-week-old lambs of the Chios (n=10), Serres (=10) and Karaguniki (n=10) breeds, born in October 1984. The first appearance of spermatozoa in the ejaculate of the Chios, Serres and Karaguniki lambs occurred at 20.1+/-0.31 (x +/-SEM), 20.4+/-0.37 and 20.6+/-0.54 weeks of age, respectively, when the lambs had attained a body weight of 36.4+/-, 36.5+/-0.70 and 34.9+/-0.99 Kg, respectively. The volume of the ejaculate, the motility and the grade of motility of spermatozoa increased at a rapid rate up to the age of 32 weeks, when the relevant values were the same as those found in the adult animal. Density of the semen and the total number of spermatozoa per ejaculate increased at a slower rate up to the age of 46 weeks, while the percentages of dead (stained) and of morphologically abnormal spermatozoa decreased significantly between 20 and 32 weeks of age. It is concluded that the quality of the semen at the time when the first spermatozoa appear in the ejaculate is not satisfactory, but it improves in the course of the ensuing 2 to 3 months. The optimal age at which the lambs may be used for artificial insemination are 32, 36 and 34 weeks for the Chios, Serres and Karaguniki breeds, respectively.     

Testicular shape and its relationship to sperm production in mature Holstein bulls

This study was conducted to determine the relationship between testicular shape, scrotal circumference (SC) and sperm production. Twenty-seven mature Holstein bulls were evaluated subjectively and objectively for testicular shape as indicated by testicular length and width, then placed in 1 of 3 groups. Group 1 contained 17 bulls with a normal ovoid testicular shape and a length to width ratio of 1.61:1 +/- 0.01 (SEM). Group 2 was composed of 4 bulls with a long, slender testicular shape and a length to width ratio of 1.95:1 +/- 0.06 (SEM). Group 3 was comprised of 6 bulls with spheroid-shaped testicles and a length to width ratio of 1.3:1 +/- 0.03 (SEM). All the groups were statistically different for length to width ratios (P < 0.05). Length measurements from cranial to caudal pole of the testis proper were also different between groups (P < 0.05). Width or testicular diameter was different between Group 2 and Group 3 at P < 0.05; however, there was no difference between Group 1 and Group 2 or between Group 1 and Group 3. Predicted volumes and weights of testicles were not significantly different between groups. Scrotal circumference measurements were significantly different between groups (P < 0.05). Group 1 had an average SC of 43.07 +/- 0.36 cm (SEM), Group 2 of 39.33 +/- 1.18 cm (SEM) and Group 3 of 46.22 +/- 0.69 cm (SEM). Sperm production for a twice daily, 2-day-per-week collection schedule revealed a statistically significant difference for sperm output. A total of 2742 ejaculates was evaluated. A total of 1818 ejaculates was evaluated in Group 1, 440 ejaculates in Group 2 and 484 ejaculates in Group 3. The mean spermatozoal harvest per day for Group 1 bulls was 13.62 +/- 0.09 x 10(9) (SEM). Group 2 bulls with the longer-shaped testicles produced 14.82 +/- 0.18 x 10(9) (SEM) spermatozoa per day, and Group 3 bulls, with the more rounded testicle shape and the significantly larger SC produced 11.72 +/- 0.64 x 10(9)(SEM) sperm cells per day. All 3 groups were statistically different at the P = 0.05 level. The results suggest that prediction of sperm production may be dependent on factors other than SC, testicular volume, or weight. Testicular shape may influence sperm output in mature Holstein bulls.     

Trypanosomiasis-induced infertility in dromedary (Camelus dromedarius) bulls: changes in plasma steroids concentration and semen characteristics

The effect of Trypanosomiasis on concentrations of plasma steroids and semen characteristics was studied in 24 dromedary bulls. Based upon the parasitological and serological diagnosis, 18 bulls were found infected with Trypanosoma evansi (Group 2) and six were found to be free from infection and served as controls (Group 1). The infected animals exhibited signs of anaemia indicated by the decrease of packed cell volume (PCV) and haemoglobin concentration (Hb), pale mucus membranes, weight loss, lethargy, weakness and dullness. However, five animals (27.8%) of the infected group revealed elevated rectal temperatures and three animals (16.7%) revealed testicular degeneration upon palpation of their scrotal contents. Concentrations of plasma oestradiol-17beta (86.5 +/- 8.6 pg/ml versus 232.5 +/- 74.4 pg/ml) and testosterone (4.8 +/- 0.7 ng/ml versus 2.7 +/- 1.5 ng/ml) were significantly different (P < 0.05) between the control and infected bulls. Evaluation of the semen collected by electroejaculation and evaluated by a computerized cell motion analyzer revealed normal semen characteristics in the control animals compared to deteriorated ones in the infected bulls. There were highly significant (P < 0.01) decreases in sperm count (12.2 +/- 1.3/ml versus 6.5 +/- 4.9 x 10(6)/ml), motility percentage (68.2 +/- 6.7% versus 27.4 +/-15.6%), percentage of live spermatozoa (73.2 +/- 8.3% versus 35.8 +/- 8.2%) and increases in percentage of morphological abnormalities (3.3 +/- 0.6% versus 15.9 +/- 1.0%) in the infected group. An examination of the plasma hormonal profiles and semen characteristics in the infected bulls indicated that altered Sertoli cell function due to formation of immune complexes in four bulls (Group 2A), pituitary dysfunction in six bulls (Group 2B), testicular degeneration in three bulls (Group 2C) and finally trypanotolerancy in five bulls (Group 2D) are possible factors responsible for poor semen characteristics and infertility induced by T. evansi infection in dromedary bulls.     

Seminal carnitine and acetylcarnitine content and carnitine acetyltransferase activity in young Maremmano stallions

The reproductive characteristics and seminal carnitine and acetylcarnitine content as well as carnitine acetyltransferase activity of young Maremmano stallions (n=25) are reported. The stallions were subjected to semen collection in November and January; in each trial two ejaculates were collected 1h apart. The total motile morphologically normal spermatozoa (TMMNS) and the progressively motile spermatozoa at collection and during storage at +4 degrees C were evaluated. Seminal L-carnitine (LC), acetylcarnitine (AC), pyruvate and lactate were measured using spectrophotometric methods, whereas carnitine acetyltransferase activity was measured by radioenzymatic methods. Since there were no major significant differences in seminal and biochemical characteristics between the November and January trials, data were also pooled for the first and second ejaculates. Significant differences (P<0.001) were observed between the first and second ejaculates for sperm count (0.249+/-0.025 versus 0.133+/-0.014x10(9)/ml), total number spermatozoa by ejaculate (12.81+/-1.23 versus 6.36+/-0.77x10(9)), progressively motile spermatozoa (48.6+/-3.0 versus 52.6+/-3.0%) and TMMNS (3.35+/-0.50 versus 2.02+/-0.37x10(9)). In the raw semen the LC and AC were significantly higher in the first ejaculate than in the second (P<0.001), whereas, pyruvate and pyruvate/lactate ratio were higher in the second ejaculate (P<0.05). Seminal plasma AC and LC concentrations resulted higher in the first ejaculate (P<0.001). The pyruvate/lactate ratio was higher in the second ejaculate (P<0.05). Both raw semen and seminal plasma LC and AC concentrations were positively correlated with spermatozoa concentration (P<0.01); in raw semen AC was also correlated to TMMNS (P<0.01). Lactate levels of raw semen was correlated to progressively motile spermatozoa after storage (P<0.01). In the second ejaculate, significant correlations were also observed among AC/LC ratio in raw semen and progressively motile spermatozoa after 48 and 72h of refrigeration. Furthermore, AC levels were correlated to lactate concentration. The positive correlation between LC, AC and spermatozoa concentration, and between AC and TMMNS indicated carnitine as potential semen quality marker. Moreover, the correlation between AC/LC ratio and progressive spermatozoa motility after refrigeration, suggests that carnitine may contribute towards improving the maintenance of spermatozoa viability during in vitro storage.     

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.     

The expression of the aryl hydrocarbon receptor in reproductive and neuroendocrine tissues during the estrous cycle in the pig

The sprouted wheat (SW) contains the 6-methoxy-2-benzoxazolinone (6-MBOA), a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of short-term supplemental dietary SW on libido, semen and sperm characteristics of rabbit bucks. Five-month old New Zealand White pubertal rabbits (n=18) were randomly allocated to one of two treatments: supplementation or not (control) supplemented with SW. The experimental design was completely random with nine replications, experimental unit was one buck. Semen collection for each male was conducted once a week with two ejaculations during 20 weeks. The SW was given during four consecutive days prior to each semen collection. Analysis of variance was under a mixed model: treatment, ejaculate number and season were fixed and rabbit random effects. There was no effect of treatment (P>0.05) on reaction time, gel presence, volume, pH, sperm motility, sperm number per ml and sperm number per ejaculate. The percentage of normal alive spermatozoa was 13.5% greater in SW-supplemented bucks than in the control and the percentage of abnormal alive spermatozoa was 44.1% greater in the control than in the SW-supplemented bucks. The morphology of dead spermatozoa, integrity of acrosome, number of normal alive motile sperm and semen doses per ejaculate were not influenced (P>0.05) by SW supplementation. The proportion of presence of gel and semen volume in the first ejaculate was greater than the second ejaculate (+140% and +56.4%). However, the semen quality in the latter was greater (P=0.0001) than the former in terms of an increase in motility (+29.7%). Reproductive traits were more desirable (P<0.05) in winter than autumn. Dietary wilted SW as a source of biological 6-MBOA enhanced sperm characteristics in terms of a greater percentage of normal alive and lesser percentage of abnormal alive spermatozoa but did not affect the number of normal motile live sperm and suitable semen doses in rabbit bucks in autumn and winter.     

Effect of relaxin on facilitation of parturition in dairy heifers

Purified pig relaxin (3000 U/mg) was injected i.m. into pregnant Holstein dairy heifers on Day 276 or 277 to determine its effect on parturition and sequential measurements of the pelvic area, cervical dilatation, and peripheral blood-plasma concentrations of progesterone and relaxin. Treatments included phosphate-buffer saline (2 ml, Group C, N = 7), relaxin once (1 mg, Group 1R, N = 7), and twice (2 mg, 12 h apart; Group 2R, N = 7). Intervals (mean +/- s.e.) between the first injection of relaxin or PBS and calving were 64 +/- 17, 80 +/- 19 and 125 +/- 34 h for Groups 2R, 1R and C, respectively. The calving intervals were reduced in Groups 2R (P less than 0.01) and 1R (P less than 0.05) compared with Group C. The incidence of dystocia was 29% (2 of 7) in Group 2R and 43% (3 of 7) in Group 1R compared with 57% (4 of 7) in Group C (P less than 0.01). Body weights and ratios of males to females of the calves were similar (P greater than 0.05) between groups. Progesterone plasma concentrations decreased (P less than 0.01) earlier in Groups 1R and 2R compared with Group C, and this acute decrease began within 6 h of treatment. At 24 h after relaxin or PBS injection, progesterone concentrations were 2.7 +/- 1.1 ng/ml for Group 2R, 3.5 +/- 0.9 ng/ml for Group 1R, and 6.0 +/- 0.1 ng/ml for Group C. Relaxin reached peak blood-plasma levels of 19 +/- 2.2 ng/ml 1 h after injection of relaxin, but remained unchanged, 0.3 +/- 0.01 ng/ml, in Group C. Pelvic area was increased 26%, 22% and 14% and cervical dilatation was increased 109%, 76% and 53% 48 h after injection in Groups 2R, 1R and C, respectively, but these responses were similar among groups at the time of parturition. We conclude that two i.m. injections of relaxin facilitated earlier calving, acutely decreased progesterone secretion, increased cervical dilatation and pelvic area expansion, and decreased the incidence of dystocia in dairy heifers.     

Year-round testicular volume and semen quality evaluations in captive Chinchilla lanigera

In mammals, reproductive performance is usually associated with seasons. Chinchilla lanigera, an endemic South American rodent, reproduces throughout the year in captivity but its seasonal breeding pattern is not fully understood. The present study was designed to evaluate (bi-weekly) over 1 year: (1) testicular volume variations and (2) seminal volume, sperm concentration and functional activity changes. Five animals were studied; they were individually housed indoors (22.2 +/- 1.0 degrees C) under natural photoperiod in Argentina (Córdoba, 31 degrees S-64 degrees W). Semen was obtained by electroejaculation; a total of 116 ejaculates was evaluated. Monthly values for paired testicular volume were less in the middle of the summer than in other seasons (p < 0.006), while those for seminal volume and total spermatozoa/ejaculate were not significantly different; these variables ranged between 7.2-30.9 cm(3), 10-130 microL and 0.9-432.6 x 10(6), respectively. Spermatozoa concentration was (x 10(6)/mL) 2145.9 +/- 365.3 and the pH of semen was 7.3 +/- 0.0. Spermatozoa functional activity showed no significant differences between monthly evaluations; confidence intervals were calculated for the means of: motility, 92.2-95.8%; viability, 92.2-96.1%; swollen cells (hypo-osmotic swelling test), 81.2-87.7% and viable intact acrosome, 83.5-89.0%. The present study represents the first longitudinal reproductive assessment in the chinchilla male. In conclusion, males produce spermatozoa continuously that exhibit high quality functional activity.     

Aldosterone and prolactin response to exercise in the heat in circumpubertal boys.

Thermoregulatory responses to exercise in the heat, especially sweating pattern, differ between children and adults. To determine whether such differences may be related to hormonal responses and to assess the possible association between this response and physical maturation, three groups of circumpubertal boys cycled at 50% of maximal O2 uptake (three 20-min bouts with 10 min of rest between bouts) in 42 degrees C at 20% relative humidity. On the basis of Tanner staging, 11 were prepubertal (PP), 12 midpubertal (MP), and 7 late pubertal (LP). Water ingestion was encouraged to minimize dehydration. Venous blood was sampled before and immediately after the session. Changes in heart rate, rectal temperature, and percent decrease in plasma volume did not differ among groups. There was no change in plasma osmolality in any of the groups. Resting testosterone concentrations were higher with increased level of physical maturity (PP = 0.4 +/- 0.1, MP = 8.2 +/- 1.9, LP = 13.8 +/- 1.2 nmol/l; P less than 0.05). In all groups, both aldosterone (ALD) and prolactin (PRL) markedly increased after exercise in the heat (ALD: PP = 161 +/- 40 vs. 1,289 +/- 263, MP = 173 +/- 47 vs. 1,245 +/- 153, LP = 250 +/- 76 vs. 1,681 +/- 400 pmol/l; PRL: PP = 8.1 +/- 1.2 vs. 24.9 +/- 4.2, MP = 8.8 +/- 1.0 vs. 22.0 +/- 8.9, LP = 8.4 +/- 0.8 vs. 39.0 +/- 3.6 micrograms/l; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)