A whole genome scanning for quantitative trait loci on traits related to sperm quality and ejaculation in pigs

To identify quantitative trait loci (QTL) for traits related to semen and ejaculation, phenotype data including semen volume, sperm concentration, total sperm per ejaculate, sperm motility, sperm abnormality rate, semen pH value, ejaculation times and ejaculation duration were measured on 206 F(2) boar at 240 days in a White Duroc x Erhualian intercross. A genome-wide scan was performed and the entire White Duroc x Erhualian intercross was genotyped for 183 microsatellite markers covering the whole pig genome. QTL analysis was performed using a composite regression interval mapping method via QTLExpress. A total of 18 QTL were detected, including 4 genome-wide significant QTL each for semen pH on pig chromosome (SSC) 2 and SSC12, for semen volume on SSC15, and for ejaculation times on SSC17. Fourteen suggestive QTL were found on SSC1, 2, 3, 4, 6, 9, 17 and 18. To our knowledge, this is the first report about the QTL for semen and ejaculation traits in pigs, providing a start point to decipher the genetic basis of these complex traits.     

Effect of prostaglandin F2 alpha on libido, seminal quantity and quality of buffalo bulls

Four mature Murrah buffalo bulls on a regular semen collection schedule of twice a day, two days per week, were injected with 30 mg prostaglandin F2 alpha THAM salt(PGF) intramuscularly 30 minutes prior to each alternate first ejaculation for six weeks. Effects of PGF on time to initial false mount on the decoy, time to ejaculation after two false mounts (reaction time), seminal volume, sperm concentration, total sperm output, motility of fresh and thawed semen and the semen doses obtained per collection were evaluated. Treatment caused significant (P < 0.01) reduction in the time to first false mount and the reaction time for the first ejaculations but had no effect (P > 0.05) on these for the second ejaculations. Values for other quantitative and qualitative parameters did not differ (P > 0.05) due to PGF treatment. It is concluded that PGF at the dosage and frequency of administration used may be of some value in improving libido in low-libido bulls but does not alter the reproductive capacity of buffalo bulls.     

Effect of mating on sperm distribution in the reproductive tract of the male rat

Extragonadal sperm reserves in male rats were measured in different regions of the genital tract before and subsequent to normal ejaculation. In sexually rested rats, the sperm count (million spermatozoa for the paired organs) in different regions was: distal vas, 18; proximal vas, 9.8; cauda epididymidis, 229; caput + corpus epididymidis, 154. Following mating, the sperm count was reduced in the proximal and distal vas deferens and in the cauda epididymidis. The reproductive tract of mated females was found to contain 29% (no copulatory plug) or 59% (with copulatory plug) of the estimated mean ejaculate, which was estimated from the difference between the sperm counts in the sexually rested rat and following ejaculation. It is concluded that in the rat the immediate source of spermatozoa for ejaculation is the cauda epididymidis, with a smaller contribution arising from the vas deferens.     

Determination of onset of puberty in Zebu bulls under tropical conditions of northern Nigeria

Age at puberty and related phenomena were investigated in White Fulani (Bunaji - WF), Sokoto Gudali (SG) and Friesian X Bunaji (FRXWF) Zebu bulls from 28 weeks to 72 weeks of age. Pubertal traits studied included body weight, heart girth, scrotal circumference and sperm production. Puberty was defined as the age at which an ejaculated semen contained at least 50 x 10(6) spermatozoa with a minimum of 10% motility. Age at puberty was 66.89 +/- 1.0, 73.4 +/- 2.2 and 62.4 +/- 10.7 weeks for WF, SG and FRXWF bulls respectively. The Bunaji bulls were significantly younger than the Sokoto Gudali bulls at production of first motile sperm cell and also at puberty (P<0.01). The SG bulls were significantly heavier (P<0.01) and had larger heart girth (P<0.05) than the FRxWF at production of first motile sperm cells. Body weight and heart girth for all the breeds were not different at puberty (P>0.1). Scrotal circumference of the bulls between the breeds at production of first motile sperm cells and at puberty, did not differ (P 0.>1), despite the variations in age, weight and heart girth at production of first motile sperm cell and at puberty. It is concluded from the data obtained that the indigenous breeds of bulls (Bos indicus ) seem to attain puberty later than exotic breeds (Bos taurus ). The inter-play of genetic, nutritional and environmental factors as a contribution to this delay in attainment of puberty could not be ruled out.     

Effects of meldonium on sexual performance,sperm motility,testes morphology and blood biochemical markers in boars

The objective of this study was to evaluate effects of long term (90-day) administration of meldonium [3-(2,2,2-trimethylhydrazinium) propionate] (mildronate, quaterin, MET-88) on sexual performance, sperm motility, testes morphology and biochemical blood markers in boars. Boars were treated with 2.0 g of meldonium daily for 90 days. Administration of meldonium improved sexual performance and sperm motility. Thus, the reaction time (time from exposure to the dummy to the start of ejaculation) was reduced and the progressive motility of spermatozoa was significantly increased in the meldonium-treated boars compared to that of the boars of control group. In addition, the spermatogenic epithelium was thicker and proliferation of interstitial endocrine cells (Leydig cells) was observed in meldonium-treated boars. The concentration of blood serum testosterone was higher in the meldonium-treatment group than in the control group. Meldonium did not affect the concentration of creatinine, total bilirubin, total cholesterol, glucose and aspartate aminotransferase/AST, alanine aminotransferase/ALT activity in blood plasma. In conclusion, 90-day administration of meldonium improved sexual performance and sperm motility of boars and it also increased concentration of testosterone in blood serum. Further studies are necessary to substantiate the potential use of meldonium as a sperm motility and/or sperm quality-enhancing agent in livestock.     

Intrinsic post‐ejaculation sperm ageing does not affect offspring fitness in Atlantic salmon

Post‐meiotic sperm ageing, both before ejaculation and after ejaculation, has been shown to negatively affect offspring fitness by lowering the rate of embryonic development, reducing embryonic viability and decreasing offspring condition. These negative effects are thought to be caused by intrinsic factors such as oxidative stress and ATP depletion or extrinsic factors such as temperature and osmosis. Effects of post‐ejaculation sperm ageing on offspring fitness have so far almost exclusively been tested in internal fertilizers. Here, we tested whether intrinsic post‐ejaculation sperm ageing affects offspring performance in an external fertilizer, the Atlantic salmon Salmo salar. We performed in vitro fertilizations with a split‐clutch design where sperm were subjected to four post‐ejaculation ageing treatments. We varied the duration between sperm activation and fertilization while minimizing extrinsic stress factors and tested how this affected offspring fitness. We found no evidence for an effect of our treatments on embryo survival, hatching time, larval standard length, early larval survival or larval growth rate, indicating that intrinsic post‐ejaculation sperm ageing may not occur in Atlantic salmon. One reason may be the short life span of salmon sperm after ejaculation. Whether our findings are true in other external fertilizers with extended sperm activity remains to be tested.     

Pubertal development of ram lambs: Physical and endocrinological traits in combination as indices of postpubertal reproductive function

The feasibility of using combinations of prepubertal measurements of body weight (BW), testicular size, and blood hormone concentrations (LH, FSH, PRL and testosterone) as indices of postpubertal reproductive function of rams was investigated. Data obtained on a group of 14 Suffolk rams born in March was analyzed by step-wise regression. Between the ages of 30 and 190 d, BW and testicular diameter (TD) were measured every 10 d, and a series of blood samples were collected (20-min intervals for 6 h) from the jugular vein every 20 d. Assessments and blood collections were repeated at about 13 and 17 mo. Additionally, daily sperm output (DSO, sperm voided in urine) or total sperm per ejaculate (TSPE), and ejaculation frequency (EF) were determined at about 6, 13 and 17 mo of age. Juvenile data, singly and in combinations of up to 4 traits, were related to individual reproductive traits at each of the 3 postpubertal ages. Mean testosterone concentration (150 d) and TD (170 d) at the ages indicated were the traits most consistently related to testicular size and sperm output in the postpubertal period. At the other juvenile ages, multi-variable models involving combinations of testicular and endocrine measurements were usually more indicative of reproductive functions postpubertally. Even though TD or testosterone measurement near the time of puberty onset provided the best long-range prediction of adult reproductive function, multi-trait models were generally more reliable for a specific age. We believe the multi-variable approach should be considered further.     

Adjustments of ejaculation rates in response to risk of sperm competition in a fish,the bitterling (Rhodeus sericeus)

Game theory models of sperm competition predict that within species, males should increase their sperm expenditure when they have one competitor, but decrease expenditure with increasing numbers of competitors. So far, there have been few tests or support for this prediction. Here, we show that males of a freshwater fish, the European bitterling, Rhodeus sericeus, do indeed adjust their ejaculation rate to the number of male competitors by first increasing and then decreasing their ejaculation rates as the number of competitors increases. However, this occurred only under restricted conditions. Specifically, the prediction was upheld as long as no female had deposited eggs in the live mussels that are used as spawning sites. After one or more females had spawned, males did not decrease their ejaculation rates with the number of competitors, but instead they became more aggressive. This indicates that decreased ejaculation rate and increased aggression are alternative responses to increased risk of sperm competition.     

Sperm accumulation in the ampullae and cauda epididymides of bulls

Bulls that appear to have an abnormality of sperm transport accumulate large numbers of senescent sperm in the excurrent ducts of the reproductive tract. Six bulls that accumulated sperm were used to determine the number of physiological ejaculations required to deplete accumulated senescent sperm, semen traits during depletion, the period of time to re-accumulate senescent sperm after depletion, the sites of sperm accumulation, and the effect of sperm accumulation on fertility during natural service. Semen was collected from three bulls (HH, PH1, and CH1) three times daily using internal artificial vaginas placed in cows in estrus. These bulls started to produce semen with >or=70% morphologically normal sperm on the third, fifth, and seventh day, respectively. The percentage of live sperm increased from 5% to 68%, 5% to 63%, and 18% to 68% in HH, PH1, and CH1, respectively. Two weeks later the same bulls were electroejaculated every second day for five electroejaculations to deplete stores of senescent sperm. Each time, electroejaculation was continued until the semen produced had a dilute appearance. The three bulls re-accumulated senescent sperm after 1 month of sexual rest. After re-accumulation of senescent sperm, the total volumes of semen in both ampullae recovered at slaughter from HH, PH1, and CH1 were 5.0, 5.0, and 9.5 ml, respectively. The volumes of semen in ampullae recovered at slaughter from two control bulls (RA and CHC) were 1.7 and 1.9 ml, respectively. The number of sperm recovered from both cauda epididymides of HH, PH1, CH1, RA and CHC was 37.3x10(9), 23.3x10(9), 15.0x10(9), 6.9x10(9), and 7.4x10(9), respectively. Bull CH1 and a fourth bull (LM) that also accumulated sperm, started to produce semen with >or=70% morphologically normal sperm, and >or=60% progressively motile sperm on the third electroejaculation after depletion of senescent sperm by repeated electroejaculations. Pregnancy rates achieved by two bulls that accumulated senescent sperm (CH2 and PH2) were less (P<0.05) during the first week of a 21-day breeding period and there was a tendency for lesser pregnancy rates at the end of the breeding period when compared with two normal control bulls. The present study indicates that bulls that accumulate senescent sperm may achieve greater pregnancy rates approximately 1 week after beginning a period of frequent ejaculation. Re-accumulation of an increased percentage of senescent sperm would likely occur after 1 month of sexual rest.     

Bower‐building behaviour is associated with increased sperm longevity in Tanganyikan cichlids

We investigated the evolutionary relationship between spawning behaviour and sperm motility traits among Tanganyikan mouth‐brooding cichlid species that have developed diverse mating behaviours and male sexual traits. Mouth‐brooding behaviour is common among these fish, but different species demonstrate a range of spawning behaviours, bower construction, male sexual traits and timing of gamete release. We observed spawning behaviours and compared sperm motility traits of 28 Tanganyikan mouth‐brooding cichlids to elucidate the evolutionary correlations between these traits. Sperm longevity was considerably longer in bower‐building species that construct crater‐shaped spawning sites compared with species that do not build bowers. Male bower builders released sperm in the pit of the bower prior to spawning, and the time from ejaculation to fertilization was longer. Conversely, most mouth‐brooding cichlids deposited semen directly into the female buccal cavity, and spawned eggs were immediately picked up to be placed inside the cavity; thus, the time from ejaculation to fertilization was short. These observations suggest that increased sperm longevity is favoured in bower builders. Comparative phylogenetic analyses suggested that bower‐building behaviour and greater time from ejaculation to fertilization are associated with the extension of sperm longevity, whereas sperm competition rank does not play a major role. In addition, bower‐building behaviour preceded the emergence of increased sperm longevity. These results indicate that the extension of sperm longevity as a result of the emergence of bower builders may have acted as an evolutionary attractor for sperm longevity.     

Effect of semen collection practices on sperm characteristics before and after storage and on fertility of stallions

This study analyzed effects of different methods and intervals of semen collection on the quantity and quality of fresh, cool-stored, and frozen-thawed sperm and fertility of AI stallions. In Experiment 1, ejaculates were obtained from six stallions (72 ejaculates per stallion) using fractionated versus non-fractionated semen collection techniques. Initial sperm quality of the first three jets of the ejaculate was not different from that of total ejaculates. Centrifugation of sperm-rich fractions before freezing improved post-thaw motility and sperm membrane integrity when compared to non-centrifuged sperm-rich fractions or non-fractionated centrifuged ejaculates (P<0.05). In Experiment 2, semen from four stallions (60-70 ejaculates per stallion) was collected either once daily or two times 1h apart every 48 h. The first ejaculates of double collections had significantly higher sperm concentrations, percentages of progressively motile sperm (PMS) after storage for 24h at 5 degrees C and lower percentages of midpiece alterations than single daily ejaculates. Semen collected once daily showed significantly lower values of live sperm after freezing and thawing than the first ejaculate of two ejaculates collected 1h apart every 48 h. In Experiment 3, semen was collected from 36 stallions (> or =12 ejaculates per stallion) during the non-breeding season and the time to ejaculation and the number of mounts was recorded. When time to ejaculation and the number of mounts increased, volume and total sperm count (TSC) also increased (P<0.05), whereas a decrease was observed in sperm concentration, percentage of PMS after storage for 24 h at 5 degrees C, percentage of membrane-intact sperm in fresh semen (P<0.05) as well as motility and percentage of membrane-intact sperm of frozen-thawed sperm (P<0.05). In Experiment 4, AI data of 71 stallions were retrospectively analyzed for the effect of number of mounts per ejaculation and frequency, time interval of semen collections on pregnancy, and foaling rates (FRs) of mares. Semen volume increased, but sperm concentration and percentage of PMS after 24-h cool-storage decreased with increasing number of mounts on the phantom (P<0.05). A statistically significant inter-relationship was demonstrated between frequency and interval of semen collection and FR. Mares inseminated with stallions from which semen was collected frequently (> or =1 on an average per day) showed significantly higher FRs than mares inseminated with semen from stallions with a daily collection frequency of 0.5-1 or <0.5. FR of mares inseminated with stallions having 0.5-1 days between semen collections was significantly better than FR of mares that were inseminated with stallions having semen collection intervals of 1-1.5 days or >2.5 days.     

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

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

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.     

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.     

Effect on ejaculatory performance and semen parameters of sexually-satiated male goats (Capra hircus) after changing the stimulus female

The association between stimulation of sexual activity and semen characteristics of sexually mature goats was evaluated. Nine 2-year-old criollo bucks were used. Each buck was subjected to 8-weekly trials in which one of the following two treatments was alternately applied. In treatment 1, males were individually exposed to the same estrus-induced female during a 4-h period, and ejaculates were collected and analyzed throughout. Treatment 2 was the same, except that a different doe replaced the stimulus animal for the third and fourth hours. The total number of ejaculations and total sperm number for four sets of data was different (P<0.01) for treatments 1 and 2 (184 versus 252 ejaculations with a total of 354.3 versus 477.1 billion sperm, respectively). In treatment 2, when first and last ejaculation of each male with the (original) stimulus animal were compared, total sperm per ejaculate decreased (P=0.08) from 4.14+/-3.8 x 10(9) to 0.77+/-0.7 x 10(9), while this value increased (P=0.05) to 3.04+/-2.3 x 10(9) after a new female was introduced, which represented a recovery of 67.35%. All males achieved a first ejaculation with the original stimulus animal while on average, only three achieved a seventh service. After changing the stimulus animal, all males ejaculated again. It is concluded that changing the stimulus animal after a 2-h continuous exposure to an estrous female stimulates sexual activity and increases sperm output in male goats.     

Influence of exogenous testosterone on sperm production, seminal quality and libido of stallions.

The effect of exogenous testosterone on sperm production, seminal quality and libido was studied in 24 stallions. Based on pretreatment data, a stallion was assigned to 1 of 3 groups each containing 8 animals. One member of each group received 0 (Group 1), 50 (Group 2), or 200 micrograms (Group 3) testosterone propionate per kg body weight every 2 days for 88 days. The lower dose of testosterone had no significant effect on most of the parameters studied: the higher dose depressed total scrotal width at Day 90 post-treatment (P less than 0.01), total spermatozoa ejaculated between Days 60 and 90 (P less than 0.01) and 96 progressively motile spermatozoa between Days 60 and 90 (P less than 0.10). One half of the stallions from each treatment were castrated on Day 90. In the operated stallions, the mean number of spermatids per g testicular parenchyma in the controls (Group 1) was significantly (P less than 0.05) higher than that in Group 3 whereas the difference between the number of spermatids/testis in the same stallions of these two groups was significant only at P less than 0.1. Testosterone propionate treatment did not influence time to erection, interval from first mount to ejaculation or number of mounts per ejaculation. The treatment of normal, intact stallions with testosterone propionate did not enhance libido and caused a severe depression of reproductive capacity.     

Oral imipramine and intravenous xylazine for pharmacologically-induced ex copula ejaculation in stallions.

This study is part of ongoing work toward developing pharmacological methods for enhancing and inducing ejaculation in stallions with ejaculatory dysfunction or disabilities that interfere with normal breeding behavior. The objective was to evaluate a treatment regimen involving oral imipramine followed by intravenous xylazine that, in uncontrolled field clinical trials, had shown promise for a higher rate of ejaculation and fewer side effects using a more easily obtained and administered form of imipramine. Eight stallions each underwent eight trials in which treatment consisted of imipramine hydrochloride (3mg/kg, orally in a small portion sweet feed) followed 2h later by xylazine hydrochloride (0.66 mg/kg, intravenously). Trials were conducted with the stallion in a stall. Semen was collected using a collection bag secured over the prepuce with a girth band. Overall, 44 of the 64 attempts (68%) resulted in ejaculation. Within-stallion ejaculation rate ranged from 3 of 8 to 7 of 8 attempts. Interval from xylazine treatment to ejaculation ranged from 1.2 to 14 min. As is typical for induced ejaculations in which imipramine is included in the treatment regimen, ejaculates were of low volume, high sperm concentration, and with a higher total number of sperm than for in copula ejaculates of these stallions. These results represent a modest improvement in rate of ejaculation over previous treatment regimens.     

Éjaculation provoquée par le vibromassage ou l’électrostimulation endorectale chez le blessé médullaire: injection intracytoplasmique de spermatozoïdes obtenus par stimulation endorectale chez neuf couples

800 to 1,000 cases of traumatic spinal cord injury (S.C.I.) are observed in France each year. At present time, there are more than 35,000 survivors of S.C.I. in France. Studies show that 80% of injuries occur in men and 82% occur in individuals between the ages of 16 and 45 years. It is well known that more than 80% of men with S.C.I. suffer from ejaculation dysfunction. Since most of these couples are young, many desire a family and seek help to remedy their infertility. Two methods are mainly used to retrieve sperm from S.C.I. men: penile vibratory stimulation and rectal electrostimulation. Penile vibratory stimulation to induce ejaculation is recommended as first-line treatment, and S.C.I. men should only be referred for electroejaculation after failure of this technique. More than 70% of patients respond to penile vibratory stimulation with anterograde ejaculation. Patients who fail to ejaculate by penile vibratory stimulation are treated by electroejaculation. Their ejaculates often have normal sperm counts, but with a higher proportion of immotile sperm than in men without S.C.I. The authors report the pregnancy outcome of a series of 9 couples undergoing combined electroejaculation and in vitro fertilization with intracytoplasmic sperm injection: 25% pregnancies per cycle and 33% pregnancies per couple.     

Early puberty in local Naga boar of India: assessment through epididymal spermiogram and in vivo pregnancy

Male Naga pig of India, a miniature breed is known for its meat quality and early puberty. No scientific efforts were made to verify the farmers' view that this breed reaches puberty at around 2 months of age. A preliminary study was, therefore, conducted with the objectives: (a) to find out the age at puberty based on mature spermiogram and in vivo pregnancy and (b) to record the sperm morphology in different parts of the epididymis. Animals were selected from two different age groups: group I aged 53 days and 2.4 kg and group II of 85 days and 3.0 kg. Semen samples collected from different sections of epididymis were analyzed for sperm motility, live spermatozoa, and morphological abnormalities. Motility increased (P<0.01) and live spermatozoa and total morphological abnormalities decreased (P<0.001) from caput through cauda epididymis in both the groups. Sperm motility, live spermatozoa and morphologically normal spermatozoa in each section of the epididymis were higher (P<0.01) in group II than I. Boars with >60% progressive motility, >70% live spermatozoa, <15% total morphological abnormalities and <10% abnormal acrosomes in cauda epididymal spermatozoa were considered mature spermiogram. As per this definition, pigs of group II had only mature spermiogram. In vivo pregnancy confirmation indicated that Naga boar could impregnate female as early as 90 days of age. In conclusion, Naga boar attained puberty by not later than 3 months with 3.0 kg, which is the lowest body weight at puberty in this species reported so far, as reflected by mature epididymal spermiogram and in vivo pregnancy confirmation.     

Chromatin integrity of ram spermatozoa. Relationships to annual fluctuations of scrotal surface temperature and temperature-humidity index

The objective of the present study was to explore the potential relationships of ovine sperm chromatin integrity, quantified using the sperm chromatin structure assay (SCSA), to the heat load of the scrotum and the discomfort felt by the animals because of fluctuations of microclimatic factors at different time periods before ejaculation. Ejaculates were collected once per week from five Chios rams and four East Friesian rams for 12 months and stored in liquid nitrogen. Frozen-thawed semen samples were analyzed using the SCSA, to determine the DNA fragmentation index (DFI) and the percentage of cells outside the main sperm population (%DFI) in each one of the samples. Scrotal surface temperature (SST) of each ram was measured using an infrared thermometer on a daily basis. Ambient air temperature and relative humidity were recorded at hourly intervals throughout the experimental period and temperature-humidity index (THI) was used to assess the discomfort felt by the rams. Mean values of SST (SST_mean) and THI (THI_mean) were computed for eight different time periods (up to 61 days) preceding each ejaculation day (Day 0). A linear mixed-effect model analysis was performed to describe the relation of SCSA parameters to collection month, SST_mean, and THI_mean of different time periods before ejaculation. The results of the statistical analysis revealed a relation of %DFI to the SST_mean of the last 12 days preceding ejaculation, namely the period that resembled the phase of epididymal maturation. On the contrary, the variation of DFI was most adequately described by the linear mixed-effect model applied for Days 54 to 48 before ejaculation, which resembled the phase of spermatogonial mitoses. The effect of collection month was significant for DFI and %DFI, with semen samples collected in September and February exhibiting the lowest DFI values; a less profound seasonal pattern was detected for %DFI. The effect of THI_mean on DFI and %DFI was proven nonsignificant in regard to all time periods. In conclusion, a relation of SCSA parameters to SST_mean of different periods before ejaculation was shown in the present study, implying an effect of scrotal microenvironment on intratesticular and epididymal sperm population. In contrast, we failed to detect any effect of microclimate-induced discomfort felt by the animals on the chromatin integrity of frozen-thawed ram spermatozoa.