Semen quality and fertility after heat stress in boars

Sperm morphology and the fertilizing capacity of ejaculated spermatozoa were examined in 6 Swedish Landrace boars before and after heat stress. The boars were exposed to 35° C during 100 h in a climatic room. Fertility was measured by insemination of gilts before and at various times after heat stress. Each gilt (n = 44) was inseminated with a total of 5×10⁹ spermatozoa diluted to 10O ml with EDTA-glucose diluent and fertilization was assessed by examining recovered ova 2 days after insemination.Changes in semen quality varied among the boars from a very weak response in 2 boars to pronounced semen alterations occurring 2–6 weeks after heat stress in the other boars. A close relationship was found between seminal changes and fertilization rates, all ejaculates which had high fertilization rates being of the same quality as the pre-exposure ejaculates. The ejaculates that had poor fertility were characterized by lowered sperm motility and increased numbers of spermatozoa with abnormal heads, proximal cytoplasmic droplets and nuclear pouch formations.     

Endocrine effects of heat stress in boars

The purpose of this study was to describe the temporal changes in peripheral plasma levels of testosterone and Cortisol in boars during and after heat stress. A total of 8 boars were utilized, 4 of them were exposed to 35°C, for 100 h in a climatic room, and 4 served as controls and were kept at 20 °C for 100 h in the climatic room.Blood samples were obtained via permanent vein catheters 3 times daily from 5 days before heat stress until 20 days after termination of heat stress. Testestorone levels were determined by radioimmunoassay and Cortisol by a competitive protein binding technique.For both hormones the pre-exposure levels were similar in both groups of boars. The control boars had significantly higher testosterone levels, while being in the climatic room, than during any other period. The experimental boars had slightly increased testosterone levels during the first day of heat stress and thereafter continuously decreased levels. In the control boars the testosterone levels returned to pre-exposure levels immediately after removal from the climatic room, whereas in the experimental boars the testosterone levels were dramatically increased during the first 5 days after exposure. The differences in Cortisol levels, between the 2 groups of boars were restricted to the period spent in the climatic room. During this period the experimental boars had significantly higher Cortisol levels.Key words: boars, heat stress, testosterone, cortisol     

Alkaline and Acid Phosphatase Activity, pH and Osmotic Pressure of Boar Semen

Alkaline phosphatase activity was recorded in forty ejaculates of the sperm rich fraction of boar semen as 9,790 ± 5,250 Klein-Babson-Read units per 100 ml. of seminal plasma. Acid phosphatase activity in the same ejaculates was 681 ± 304 Babson-Read units per 100 ml. of seminal plasma. No alkaline phosphatase activity was detected in the seminal plasma of vasectomized boars.

The pH of the sperm rich fractions was 7.69 ± 0.33 and the osmotic pressure was 313.56 ± 7.98 milliosmols.

     

Effect of male accessory gland secretions on sensitivity of porcine sperm acrosomes to cold shock, initiation of motility and loss of cytoplasmic droplets

Hyaluronidase release was used as an index of acrosomal membrane damage during cold shock of epididymal boar sperm and ejaculated sperm from intact and vesiculectomized boars. Sperm were also incubated with seminal plasma from intact and vasectomized boars to examine the contributions of male accessory gland secretions. Acrosomal membranes of epididymal sperm were more resistant to cold shock than those of ejaculated sperm. Only 36% of the hyaluronidase released by ejaculated sperm was released by the epididymal sperm in spite of similar hyaluronidase content of the sperm. Preincubation of epididymal sperm in seminal plasma from both intact and vasectomized boars increased resistance to cold shock by 60 to 80%. Initial dilution of epididymal sperm with seminal plasma, rather than Ringer-fructose buffer, was associated with low progressive motility and with retention of cytoplasmic droplets. In contrast, acrosomal membranes of ejaculated sperm from intact and vesiculectomized boars exhibited similar sensitivity to cold shock, releasing hyaluronidase capable of forming .20 and .19 mumol N-acetylglucosamine from hyaluronic acid/10(8) sperm in 8 min. Moreover, seminal plasma from vasectomized boars had no effect on acrosomal sensitivity to cold shock of ejaculated sperm from vesiculectomized boars.     

长白公猪血清和精浆中元素含量对精液品质的影响

本试验旨在研究不同精液品质特征长白公猪血清和精浆中元素含量的差异,分析血清和精浆中元素含量对精液品质的影响。基于107头长白公猪的1402次精液品质记录,将公猪群按照精液可利用率划分为3组:低利用率组(利用率<60%,n=21)、中等利用率组(60%≤利用率≤80%,n=27)和高利用率组(利用率>80%,n=59)。采集每头长白公猪的血清和精浆样品,采用电感耦合等离子体质谱法检测血清和精浆中营养元素和毒性元素含量。结果表明:1)低利用率组长白公猪的有效精子数和精子活力显著低于中等利用率和高利用率组(P<0.01),精子畸形率显著高于中等利用率和高利用率组(P<0.01)。2)不同利用率组间长白公猪的血清和精浆元素含量无显著差异(P>0.05);但在血清和精浆元素含量与精液品质参数相关性分析中发现,精浆铅元素含量与精子活力呈显著负相关(P<0.05),与精子畸形率呈显著正相关(P<0.05)。3)对精浆铅含量分组进一步分析发现,精浆铅含量为0μg/L时长白公猪的精子畸形率显著低于精浆铅含量>10.0μg/L时(P<0.05),精子畸形率降低约6.11%。总的来说,长白公猪精浆中毒性元素铅的存在会通过损害精子活力和形态,影响公猪精液品质。     

The effect of exogenous administration of oestrogens on the function of the epididymis and the accessory sex glands in the boar.

Three normal, sexually mature young boars of Swedish Yorkshire breed were treated with daily intramuscular injections of diethylstilboestrol and/or oestradiolbenzoate for a total period of 13–15 weeks. Whole ejaculates were collected on a dummy sow with an artificial vagina twice a week. The ejaculate was examined as regards semen volume, sperm concentration, sperm motility and sperm morphology. The seminal plasma was analysed for Na, K, Cl, Mg, inorganic phosphate, total protein and fructose. Testicles, epididymides and the accessory sex glands were obtained at slaughter. Material from epididymal segments A, B, D_b, F_a and F_b was collected and examined for sperm morphology. Spermatocrit, osmotic pressure and plasma concentrations of Na, K, Gl, total protein and GPC were assessed in material from epididymal segment F_a. The sex glands and the accessory sex glands were examined maeroscopically and microscopically.The semen volume, the sperm concentration and consequently the total sperm count per ejaculate showed a gradual increase during the course of the investigation. This is to be expected as the boars used were comparatively young at the beginning of the experiment. These values were all within normal limits for adolescent boars.Taking all the characteristics examined into consideration no conclusive evidence was found that an exogenic administration of oestrogens to intact boars has any influence on the function of the epididymis and the accessory sex glands.     

A comparative study on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen in boars

A comparative study was carried out on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen of boars. A total of 22 boars were used in this study. The boars, which ranged in age from 8 to 14 months, were of Swedish Landrace and Swedish Yorkshire breed. All boars used presented a normal semen picture. A dummy sow and an artificial vagina were employed for semen collection. The semen was collected as whole semen and as semen fractions in 10 nil volumes. The contents of the cauda epididymidis was removed post mortem.The following parameters were investigated: sperm concentration, dry weight of spermatozoa and of seminal plasma, osmotic pressure, sodium, potassium, chloride, inorganic phosphorus, calcium, magnesium, total protein, GOT, GPT, and alkaline phosphatase in seminal plasma. Paper electrophoresis was carried out on seminal plasma. Tlxe results of the analysis are summarized in Tables 1–6.The sperm concentration was approximately 3.2 mill./mm3 in the cauda epididymidis, 1 mill./mm³ in the sperm-richest fraction (II) and 0.25 mill./mm3 in whole semen. The dry weight (expressed in per cent dry matter) of spermatozoa was highest in the cauda epididymidis (25.47 %), showing a tendency to decreasing in semen fractions I—IV and was lowest in whole semen (15.29 %). The per cent dry weight in plasma was higher in the cauda epididymidis (4.56 %) than in semen fraction I (2.20 %). In semen fractions I—IV the per cent dry weight rose from 2.20 (U to 4.51 % and reached the level of approximately 3.80 % in the sperm-free fractions V—VII. The osmotic pressure was significantly higher in the cauda epidi-dymal plasma than in the whole seminal plasma or the seminal plasma fractions. The same phenomenon was observed in a boar where the cauda epididymal content was collected in vivo from a patent established fistula. There appears to be a connection between the per cent dry weight of spermatozoa and the osmotic pressure, which means that the per cent dry weight of the cauda epididymal spermatozoa decreases when mixed with the accessory gland secretions, which have a lower osmotic pressure. The fall in per cent dry weights is thought to be caused by an intake of water.The amount of sodium, chloride and magnesium was higher in ejaculated seminal plasma than in cauda epididymal plasma. The reverse was true for inorganic phosphorus and potassium. Moreover the sperm-free fractions contained more sodium, chlorides and magnesium than the sperm-containing fractions, while the concentration of potassium and inorganic phosphorus was comparatively higher in the sperm-containing fractions. A connection is apparent between sperm concentration and the potassium, inorganic phosphorus and magnesium levels. Statistical analysis of the values of chloride and magnesium revealed significant differences between individual boars for most of the semen fractions.The concentration of plasma proteins in the cauda epididymidis was approximately the same as in whole semen and in the semen fractions except for fraction I, which contained a relatively low concentration. As regards total protein there were significant differences between individual boars in most of the semen fractions as well.The paper electrophoretic pattern of epididymal plasma was different from that of semen plasma. Thus there were three or four distinct components in the cauda epididymidis numbered 1, 2, 3, and 4, and three distinct components in whole seminal plasma numbered 3, 4, and 5, while the sperm-richest semen fractions contained four components (2, 3, 4, and 5) and the others three components, namely 3, 4, and 5.The level of GOT was high in the cautlu cpiflidymill contents (99.1 i. u./ml) compared with that for whole seminal plasma (99.1 i.u/ml). In semen fractions there was a clear positive correlation between the level of GOT and the sperm concentration. The GPT concentration wis as a whole low and. in contrast to GOT. somewhat higher in the sperm-free fractions than in the sperm-containing fractions. The concentration of alkaline phosphatase was very high in cauda epididymal plasma (31,463 i. u./ml) as well as in the sperm-rich fractions (e.g. 7,096 i. u./ml in fraction II). Preliminary investigation has moreover revealed a very low alkaline phosphatase concentration in seminal plasma of vasectomized boars, which condition suggests thai the main origin for alkaline phosphatase in boars is the testis and epididymis.     

Effect of Anserine and Carnosine on Sperm Motility in the Japanese Quail

Sperm motility is considered as one of the most important traits for successful fertilization, but the motility of an ejaculated sperm decreases with time when stored as liquid. It is reported that seminal plasma serves as a nutrient rich medium for sperm and plays an important role in sperm motility and its fertilization ability. Several studies have reported that imidazole dipeptides such as anserine and carnosine affect sperm motility and its fertilization ability in mammals. In this study, we report the presence of anserine and carnosine in the male reproductive tract of the Japanese quail. Abundant levels of anserine (44.46 µM) and carnosine (41.75 µM) were detected in the testicular fluid and seminal plasma respectively using the amino acid analyzer; however, seminal plasma solely contained carnosine. When the ejaculates were incubated with anserine or carnosine, we found that both the dipeptides improve sperm motility parameters such as straight line velocity, curvilinear velocity, average path velocity and amplitude of lateral head displacement after in vitro sperm storage at 15°C. These results indicate that imidazole dipeptides are present in the male reproductive tract and may improve sperm quality during in vitro sperm storage in the liquid states.     

牛磺酸对种公猪精液品质、血清激素含量及精浆抗氧化能力的影响

本试验旨在研究牛磺酸(Tau)对种公猪性欲、精液品质、血清激素含量及精浆抗氧化能力的影响。选用24头年龄、体重相近的健康成年大约克夏种公猪,随机分为4个组,每组6个重复,每个重复1头猪。各组分别饲喂牛磺酸添加水平为0(对照组)、2、4、6 g/kg的饲粮,试验期90 d,分为1~45 d和46~90 d 2个阶段。结果表明:1)试验46~90 d时,添加6 g/kg牛磺酸显著提高了种公猪的性欲(P0.05)、采精量(P0.01)、精子活力(P0.05),4 g/kg牛磺酸改善了精子密度和精子畸形率(P0.05);2)与对照组相比,6 g/kg牛磺酸水平组极显著提高了种公猪血清促黄体素(LH)含量(P0.01),显著提高了睾酮(T)含量(P0.05);3)试验46~90 d时,6 g/kg牛磺酸显著降低了种公猪精浆丙二醛(M DA)含量(P0.05),显著提高了超氧化物歧化酶(SOD)活力(P0.05),4 g/kg牛磺酸显著提高了谷胱甘肽过氧化物酶(GSH-Px)活力(P0.05)。由此可见,饲粮中长期添加牛磺酸可以调控种公猪血清激素含量,增加精浆抗氧化能力,进而增强种公猪性欲,提高种公猪精液品质,本试验条件下牛磺酸适宜添加水平为6 g/kg。     

Effect of vitamin supplements on some aspects of performance, vitamin status, and semen quality in boars

The aim of the present study was to determine the effects of dietary supplements of vitamins on vitamin status, libido, and semen characteristics in young boars under normal and intensive semen collection. Sixty Landrace, Yorkshire, and Duroc boars were allocated randomly from 6 to 10 mo of age to one of the following diets: 1) basal diet (industry level) for minerals and vitamins (Control, n = 15); 2) basal diet supplemented with vitamin C (ASC, n = 15); 3) basal diet supplemented with fat-soluble vitamins (FSV, n = 15); and 4) basal diet supplemented with water-soluble vitamins (WSV, n = 15). After puberty (approximately 12 mo of age), semen was collected at a regular frequency (three times every 2 wk) for 5 wk. Thereafter, all boars were intensively collected (daily during 2 wk). A recovery period (semen collection three times every 2 wk) followed and lasted for 10 wk. Sperm quality (percentage of motile cells and percentage of morphologically normal cells) and quantity (sperm concentration, semen volume, and total sperm number) were recorded as well as direct and hormone related measurements of boar libido. Blood and seminal plasma samples were taken to monitor vitamin status. High concentrations of B6 (P < 0.05) and folic acid (P < 0.05) were observed in the blood plasma of WSV boars, whereas greater concentrations of vitamin E (P < 0.01) were obtained in FSV boars. In the seminal plasma, folic acid concentrations tended to be greater in WSV boars (P < 0.08). During the intensive collection period, there was a tendency (P < 0.06) for semen production to be greater in WSV boars, the effect being less pronounced (P < 0.10) in FSV boars. During the recovery period, the percentage of motile sperm cells was greater in WSV boars (P < 0.03) and, to a lesser extent, in FSV boars (P < 0.10) compared with Control boars. Sperm morphology and libido were not affected by treatments. These results indicate that the transfer of vitamins from blood to seminal plasma is limited and the dietary supplements of water-soluble and fat-soluble vitamins may increase semen production during intensive semen collection.     

The chemotactic properties of porcine seminal components toward neutrophils in vitro

Our objectives were to investigate the mechanisms of postbreeding inflammation in swine by examining the chemotactic properties of polymorphonuclear neutrophilic granulocytes (PMN) and of various populations of spermatozoa and seminal plasma. Epididymal spermatozoa from two boars obtained under sterile conditions, washed ejaculated spermatozoa from two boars, and pooled seminal plasma from eight boars of known fertility were examined for chemotaxis to PMN. The chemotaxis of blood-derived PMN in response to sperm and seminal plasma was evaluated and expressed as a percentage of a positive control (lipopolysaccharide-activated blood plasma). The mean chemotactic effect of washed sperm alone (4.4+/-0.04) and of epididymal sperm alone (3.4+/-0.06) was not different from that of the negative controls (3.1+/-0.05) of McCoy's medium with 10% heat-inactivated fetal calf serum. A marked chemotactic effect was detected when washed ejaculated and epididymal sperm were incubated with blood plasma, compared with blood plasma without spermatozoa (P < 0.001). Washed sperm in blood plasma (86.2+/-5.6) and epididymal sperm in blood plasma (83.9+/-7.7) were different from blood plasma alone (11.2+/-1.5), but no differences were detected between the two populations of sperm. This effect, however, was not completely inhibited by heat inactivation of the blood plasma. The chemotactic response of washed ejaculated and epididymal spermatozoa incubated in lipopolysaccharide-treated, heat-inactivated blood plasma were greater than that of the negative control (P < 0.05). Polymorphonuclear neutrophilic granulocyte migration toward seminal plasma was similar to the negative control (4.0+/-0.04 vs 3.1+/-0.05). It seems that porcine epididymal sperm and ejaculated sperm activate chemotactic components in porcine blood plasma and heat-inactivated blood plasma, suggesting that, at least partially, a heat-stable (noncomplement) blood plasma component may be involved in sperm-induced PMN chemotaxis. In contrast, porcine seminal plasma was not chemotactic to PMN. These results support the hypothesis that spermatozoa play an active role in initiating postbreeding endometritis.     

骨桥蛋白在长白公猪生殖细胞中的表达及其与繁殖性能的相关性

本试验旨在研究骨桥蛋白（osteopontin,OPN）在长白公猪生殖细胞中的表达和定位,并探究其与公猪繁殖性能的相关性。试验采集了长白公猪精液和不同阶段（3日龄、3月龄、6月龄和12月龄）的睾丸组织,通过蛋白印迹的方法检测OPN蛋白在精液和不同月龄睾丸中的表达,通过免疫组化的方法对OPN蛋白在公猪睾丸细胞中进行定位;同时,根据配种胎次≥ 20胎,3次配种公猪为同一头的标准,筛选并采集17头长白种公猪精液,统计相对应的1 388头母猪的生产成绩,计算得到公猪繁殖性能指标（包括窝产总仔数、窝产活仔数、分娩率和繁殖力）。低温离心精液分离得到精子和精浆,丙酮法提取精浆蛋白,Lysis buffer方法提取精子蛋白,最后运用BCA和ELISA的方法检测精子和精浆中OPN蛋白的含量,分析OPN蛋白与公猪繁殖性能的相关性。蛋白印迹结果显示,OPN在精子、精浆和各月龄阶段的长白公猪睾丸中均以两种形式表达（67.4和33.7 ku）,且67.4 ku的形式在3月龄公猪睾丸中表达量最高;免疫组化的结果显示,OPN在长白公猪的初级精母细胞、次级精母细胞和精子细胞中表达,在精母细胞、支持细胞和间质细胞中无表达;BCA和ELISA结果显示,精子中的OPN蛋白含量是精浆中的7倍（P<0.05）,精液中的OPN蛋白与公猪窝产活仔数显著正相关（P<0.05）。本试验结果表明,OPN在各阶段的长白公猪睾丸中都有表达,且在精子和精浆中也有表达,这可能与公猪的繁殖性能有关,从而为后期OPN蛋白在公猪受精力的研究奠定基础。     

Relationship between sperm quality traits and field-fertility of porcine semen

An investigation involving seven boars, active in artificial insemination, and 1,350 multiparous sows was conducted at a private farm and aimed at examining the relationship between sperm quality traits and boar fertility in terms of farrowing rate and litter size. This experiment was done for 6 months. The semen samples were evaluated for subjective sperm motility and concentration. Ejaculates with at least 1 × 10⁸ sperm/mL and 70% sperm progressive motility were extended with a commercial medium to 30 × 10⁶ sperm/mL and used for artificial insemination (AI). AI dose was 100 mL semen containing 3 × 10⁹ spermatozoa. Aliquots of diluted semen were assessed for live morphologically normal spermatozoa (LMNS, eosin-nigrosin stain exclusion assay) and sperm chromatin instability (SCI, acridine orange assay). Farrowing rates according to different boar sperm varied (p < 0.001) from 59.3 to 88.92%. The mean values of LMNS (47.2~76.5%) and SCI (0.16~4.67%) differed significantly among boars. LMNS (r = 0.79, p < 0.05) and SCI (r = -0.90, p < 0.02) accounted for 62.2 and 81.7% of the variability in farrowing rates, respectively. After the combination of sperm traits, the relationship between percentage of LMNS with stable chromatin structure and farrowing rate was significant (r = 0.86, p < 0.05). The number of live piglets per parturition was not significantly correlated with sperm quality attributes. In conclusion, boar fertility after AI with freshly diluted semen can be predicted based on the evaluation of sperm morphology and chromatin integrity.     

The infestiveness of heat and cold exposed diphyllobothrium latum plerocercoids on golden hamster

The infestiveness of heat (56°C/5 min. and 50°C/5 min.), and cold (−10°C and −6°C) exposed Diphyllobothrium latum plerocercoids was studied by administration to golden hamsters (Mesocricetus auratus). The cold exposed larvae were subjected to an exposure, analogous the freezing of fish and which is cut off when the temperature has declined either to −6°C or −10°C. The plerocercoids were administered to the hamsters under inhalation anaesthesia, 5 larvae per hamster. Out of 150 normal control plerocercoids administered on 30 hamsters, 74 adult worms developed, indicating 49 % infestiveness. Tests carried out with 105 56°C/5 min. exposed larvae on 21 hamsters, 45 50°C/5 min. exposed larvae on 9 hamsters, and 100 larvae exposed to −10°C on 20 hamsters all gave negative results, while out of 50 −6°C exposed larvae on 10 hamsters 3 developed to adult worms. The results show that the 56°C/5 min. and −10°C exposed larvae, which in previous studies have been considered to be inactivated on the basis of the resultant permanent immobilization, were not able to develop further in the host. Thus permanent immobility seems to be a reliable criterion of larval death.     

Serum non-esterified fatty acids and plasma glycerol as indicators of fat mobilization in pregnant sheep subjected to cold stress

Fifteen pregnant ewes in an open barn were kept on a constant hay diet during the whole gestation period. The ewes were shorn as usually in fall and spring. The serum non-esterified fatty acids (NEFA) and the plasma glycerol (PG) content were followed during the gestation.The body weight, NEFA and PG values were rather constant during the first 2 months of gestation (NEFA: 430 ± 175 µeq./l serum, PG: 39 ± 19 µmol/1 plasma) indicating an adequate feeding during this period. NEFA and PG showed thereafter a parallel increase and reached maximal values at the first sampling after shearing which coincided with a marked drop in environmental temperature. NEFA was then 450 % and PG about 340 % of the normal values, indicating a strong increase in fat mobilization in this period. The shearing reduces the isolation property of the fur considerably, and the ewes have to produce extra heat to maintain the normal body temperature at low environmental temperatures. The metabolic rate after shearing was estimated to have been 2–4 times the basal rate at the temperatures in the barn. This strong increase in the metabolic rate was not compensated by an increased food intake, but resulted in increased fat mobilization.     

Influence of Boar Seminal Plasma on the Distribution of Spermatozoa in the Genital Tract of Gilts

The main purpose of the present study was to investigate whether boar seminal plasma affects the transport of spermatozoa in the genital tract of oestrous pigs or not, with special reference to the sperm transport into the oviducts. Altogether 17 gilts were used in three experiments.Experiment I. In nine gilts one uterine horn was injected surgically with 10¹⁰ spermatozoa suspended in seminal plasma and the other uterine horn with 10¹⁰ spermatozoa suspended in TESNaK-glucose buffer solution. The sperm deposition was performed under general anaesthesia. The gilts were slaughtered 1–2 or 4–6 h after insemination. The genital tract was removed and the numbers of spermatozoa determined in oviducts and in uterine horns.Experiment II. The insemination doses were prepared exactly as in Experiment I. Approx. 24 h before insemination Polyvinylchloride cannulas were inserted into the uterine lumen of the horns, drawn via the midventral incision at linea alba subcutaneously to cutaneous incisions ventral to the vulva opening. One cannula was placed in each uterine horn. At standing heat the insemination doses were slowly injected through the cannulas. The gilts were slaughtered 1 h after insemination and the numbers of spermatozoa within the genital tract were counted.Experiment III. In three gilts under general anaesthesia the uterine horns were ligated 10 cm from the uterotubal junction. The semen doses (containing 2 × 10⁹ spermatozoa), prepared as in Experiment I, were deposited into the uterine horns anterior to the ligatures through a cannula. The gilts were slaughtered 1 h after insemination, and the numbers of spermatozoa within the oviducts and ligated part of the uterine horns were counted.In all three experiments more spermatozoa were, on average, recovered in the oviducts connected to uterine horns inseminated with spermatozoa suspended in seminal plasma. In Experiments I andII this was the case for 10 of 14 gilts and in Experiment III for all the three gilts. It is therefore suggested that boar seminal plasma pro¬motes sperm transport into the oviduct of oestrous pigs. The back¬ground mechanism for this is discussed.     

Active immunization of prepubertal boars against testosterone: testicular and endocrine responses at 14 months of age

Thirteen crossbred boars were immunized at 1 mo of age against either testosterone-3-oxime-equine serum albumin (treated boars) or equine serum albumin (control boars) to test the hypothesis that active immunization against testosterone stimulates testicular growth and development in the prepubertal boar. All boars were injected with the appropriate antigen at 2, 3, 4, 5 and 6 mo of age and were slaughtered at 14 mo of age. Active immunization against testosterone resulted in an increase (P less than .05) in tritiated-testosterone binding by plasma within 60 d after the primary immunization; the degree of binding decreased by 6 mo but remained elevated (P less than .05) relative to controls through 12 mo of age. There was no effect of treatment on body weights through 12 mo of age. Concentrations of testosterone in plasma were higher (P less than .05) in testosterone-immunized boars than in controls; this increase was likely due to antibody binding rather than increased testosterone secretion because (1) concentrations of androgen in testicular parenchyma at slaughter were not altered by treatment and (2) plasma concentrations of estrogens were generally not affected by treatment. Concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were markedly suppressed in testosterone-immunized boars during the time when concentrations of these gonadotropins were high in control boars (greater than 3 mo of age). In spite of suppression of average LH and FSH concentrations, testicular weights, daily sperm production rates and seminal characteristics were similar for the two groups of boars at slaughter. (ABSTRACT TRUNCATED AT 250 WORDS)     

Concentrations of oestrogens in blood plasma and seminal plasma of boars during the postpuberal period

Concentrations of oestrogens in the blood plasma and seminal plasma of mature boars are high. However, little is known about their concentrations after reaching sexual maturity. The aim of this study was to determine the concentration of oestrogens in blood plasma and seminal plasma of boars during the postpuberal period. Free and conjugated oestrone and oestradiol-17beta were determined by radioimmunoassay in blood from the testicular vein and artery, and peripheral circulation as well as in seminal plasma collected from 18 Polish Landrace boars. The animals were divided into three groups (n = 6) according to age (8, 12 and 16 months, respectively). Oestrone was predominant free and conjugated oestrogen. The highest values of oestrogens were measured in the testicular vein (p < or = 0.05). The concentrations of oestrogens in seminal plasma did not differ from those found in the peripheral circulation. An age-dependent increase in levels of all four oestrogens (p < or = 0.05) was observed. This can be associated with biochemical maturation of the reproductive system during the postpuberal period.     

The positive effects of seminal plasma during the freezing process on cryosurvival of sperm with poor freezability in the rhesus macaque (Macaca mulatta)

The objective was to examine the effect of seminal plasma on cryopreservation of sperm from rhesus macaques. Sperm cryosurvival was evaluated by sperm motility and acrosomal integrity. Compared with slow cooling (-0.4 C/min) from 37 C (body temperature) to 4 C, rapid cooling (-16 C/min) caused cold shock in rhesus macaque sperm. The cryosurvival of sperm was decreased regardless of the presence or absence of seminal plasma (P<0.05). However, the presence of seminal plasma during cold shock at a rapid cooling rate improved sperm motility and acrosomal integrity in individual monkeys. Male-to-male variation in sperm cryosurvival was observed after cryopreservation (P<0.05), and the presence of seminal plasma during sperm cryopreservation improved sperm motility and acrosomal integrity in individual monkeys (P<0.05). Furthermore, by adding seminal plasma from monkeys with good sperm cryosurvival to sperm freezing extender, the frozen-thawed motility and acrosomal integrity of sperm from monkey with poor cryosurvival were improved (P<0.05). The present study indicated that seminal fluid is beneficial to sperm undergoing cold shock or cryopreservation in individual monkeys. The cryosurvival of sperm from rhesus macaques with poor sperm freezability could be improved by the presence of seminal plasma from males with good sperm cryosurvival. This finding provides a useful method for genetic preservation in this important species.     

Effect of dietary selenium and vitamin E on spermatogenic development in boars

An experiment involving a total of 61 crossbred boars evaluated the effects of dietary Se and vitamin E on spermatogenic development at various stages of sexual development and the prostaglandin F2alpha (PGF2alpha) content in the seminal vesicle and prostate glands at 18 mo of age. The experiment from 5.4 to 9 mo of age was conducted as a 2 x 2 factorial in a randomized complete block design. Dietary Se at 0 or .5 ppm was the first factor and vitamin E at 0 or 220 IU/kg diet was the second. From 9 to 18 mo of age, a group of sexually active and inactive boars was a third factor. Treatment diets were fed from weaning (28 d of age) to the end of the experiment. Three boars per treatment group at 5.4 (105 kg BW), 6.2 (130 kg BW), and 9.0 (150 kg BW) mo of age were killed and the testes collected. From 9 to 18 mo of age, three boars from each dietary treatment group were used for semen collection, and another set of three to four boars from each treatment group remained sexually inactive. At 18 mo, both sets of boars were killed and their testes, prostates, and seminal vesicles were collected. The testis at each age was evaluated for sperm reserve numbers and germ and Sertoli cell populations. At 5.4 or 6.2 mo of age, testicular sperm reserves were not affected by dietary Se (P > .15), at 9.0 mo of age there was a trend for a higher (P < .10) number of sperm reserves, and by 18 mo of age the Se-fed boars had higher (P < .01) numbers of sperm reserves. Vitamin E had no effect (P > .15) on testicular sperm reserves at any age period. Boars fed dietary Se had a greater number of Sertoli cells (P < .01) and round spermatids (P < .01) at 6.2 mo of age, but by 18 mo of age the boars fed Se had more Sertoli cells (P < .05), more secondary spermatocytes (P < .01), and more round spermatids (P < .05). Vitamin E did not affect Sertoli or germ cell populations at the various ages. Boars at 18 mo of age had lower PGF2alpha concentrations in the prostate (P < .05) and seminal vesicles (P < .01) when vitamin E was fed, whereas Se had no effect. Sexually active boars had lower PGF2alpha concentrations in the seminal vesicles (P < .01) than sexually inactive boars, but there was no effect (P > .15) of sexual activity on the number of Sertoli cells, primary or secondary spermatocytes, or round spermatids. Our results indicate that Se has a role in establishing the number of boar spermatozoal reserves and Sertoli cells, whereas supplemental vitamin E did not affect these criteria.