Effect of bilateral orchidectomy on serum testosterone levels in boars]

Bilateral orchidectomy caused a marked decrease in the concentration of testosterone in the bood plasma of boars already in the early post-castration stage of three hours after the operation. In the period from 3 to 207 days after castration, the pre-operation levels of plasma testosterone decrease by 84.4%, on an average. Adreno-cortical compensation of the concentration of the hormone did not occur in the post-castration period. The conclusion is that the levels of testosterone in the blood of boars are mostly of testicular origin and can be considered as the main criterion of the incretion function of the testes. The discussion concerns the practical importance of the determination of testosterone levels in the blood of boars for clinical evaluation of the hormonal function of the testes and for diagnostics of incretion hypogonodism.     

Effect of chorionic gonadotropin administration on the concentration of testosterone in the blood of boars]

In intact boars, intravenous administration of 100 to 6000 I. U. chorionic gonadotropin elicited a pronounced rise in the plasma level of testosterone, depending on the time interval from the administration of chorionic gonadotropin and on the size of the administered dose. In the blood of castrated boars such an application of choronic gonadotropin did not influence the concentration of testosterone. It was inferred that the rise in the levels of blood testosterone in boars after administration of chorionic gonadotropin was specific for testicular incretion and indicated the endocrine reserve of the testes. There is a discussion concerning the importance of the functional testing of the incretion capacity of testes for differential diagnosis different forms o incretion hypogonadism.     

The effect of LH releasing hormone on testosterone levels in the blood of boars with sexual dysfunctions]

The levels were assessed of testosterone in the blood plasma before and 90 minutes after i.v. application of 1 mg of synthetic LH-releasing hormone to 57 boars with disorders of sexual functions and to 43 boars without sexual dysfunctions. The group of animals with sexual disorders included boars with inferior ejaculate quality and low fertility (24 animals) and cases with disturbed sexual potency (33 boars). In animals with the studied changes of sexual functions, compared with boars without sexual dysfunctions, no statistically significant difference was found in the basal concentration of testosterone in the blood. LH-releasing hormone application increased significantly the testosterone levels in the group of boars without sexual disorders by 99.5% on an average and in the whole group of animals with changes in sexual functions approximately by only 65.8%. At the same time in the subgroup of inferior ejaculate quality and low fertility the post-application increase of testicular incretion reached 60.4% and in potency disorders 61.6% and was statistically insignificant in the latter. On the basis of these findings it was derived that in boars with reproduction deviations there existed a decreased incretion reserve of the system hypophysis - testicle and the involvement of this factor in the formation of the studied sexual disorders is assumed. The obtained results are discussed in view of the earlier findings about the incretion reserve of the testicles in boars with changes in sexual functions.     

The effect of chorionic gonadotropin administration on testosterone levels in the blood of boars with sexual function disorders]

Thirty-three boars with sexual dysfunctions and twenty-six boars clinically sound as to their reproductive capacity were evaluated for the testosterone levels in the blood plasma before i.v. administration of 500 i.u. of chorionic gonadotropin and two hours after the administration. A group of animals with reproduction disorders comprised boars with an impaired quality of ejaculate and low fertility ability (18 boars) and with sexual dysfunctions (15 boars). No statistically significant difference in the basal concentration of testosterone in the blood was found in the boars with the studied sexual dysfunctions, as compared with the boars with no sexual dysfunctions. Administration of chorionic gonadotropin increased significantly the plasma testosterone levels in both groups. If the effect of chorionic gonadotropin on the studied level of this hormone was compared in boars with sexual dysfunctions and in boars without any disorders, no significant differences were proved. It has been inferred from the above findings that there are no significant disorders of androgen supply and incretion reserve of the gonads in the boars with sexual dysfunctions.     

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.     

Immunoelectrophoretic and immunodiffusion studies on the seminal plasma proteins in boars

The proteins of boar seminal plasma have been studied with immunoelectrophoresis and immunodiffusion tests. Four different proteins could be identified with immunoelectrophoresis of which all seemed to be specific for seminal plasma. One of these proteins with an electrophoretic mobility corresponding to gammaglobulin had no identity with either IgG or fibrinogen.With immunodiffusion tests spur of serum proteins could be detected (albumin, transferrin and IgG).The spontaneous precipitation of boar seminal plasma in agar gels could not wholly be avoided with alterations of pH and ionic strength in the agar gel or with absorption of seminal plasma with swine red blood cells.One factor in seminal plasma which probably is of importance for the ability to agglutinate red blood cells was isolated and identified as a protein with an electrophoretic mobility corresponding to alphaglobulin. This protein could not be detected in blood serum.Keyword: seminal plasma, swine     

Sexual behavior and seminal quality of Piau boars

The objective of this study was to assess parameters of sexual behavior, seminal characteristics, testicular measurements, and their correlations in Piau boars. A total of 169 observations of the sexual behavior and prelude duration (courting) of 10 Piau boars aged from 0.8 to 6.4 years were made; semen was also collected from these animals. The testicular length (TL), testicular width (TW), testicular shape (TS; 1-5), and testicular volume (TV) of these animals were measured. The seminal physical and morphological characteristics of 60 ejaculates from 6 boars were assessed for volume of ejaculate (VOL), volume of the gelatinous portion (VOLGEL), aspect (ASP), sperm motility (MOT), spermatic vigor (VIG), spermatic concentration per milliliter (CONCML), total concentration (CONCT), and morphological characteristics (major defects [MAJDEF]; minor defects [MINDEF]; and total defects [TDEF]). The animals were subdivided into 3 age groups: G1 (0.8-2.0 years old), G2 (2.1-3.6 years old), and G3 (3.7 and 6.4 years olds). The physiological signs observed included duration of prelude (12.1 ± 4.1 minutes), time to collect semen (5.2 ± 1.8 minutes), nasonasal or genital contact behavior (71.6%), saliva emission (85.2%), urination during prelude (10.1%), penile exposure before collection (26.6%), flank stimulus (81.7%), chewing behavior (95.3%), and biting of the female or dummy (74.6%). The mean values of TL, TW, and TV were 11.8 ± 2.2 cm, 6.2 ± 1.3 cm and 754.1 ± 283.5 cm³, respectively. The older animals had the highest mean values of testicular measurements (P < 0.05) but the lowest mean values of CONCML and CONCT (P < 0.05). All the animals presented similar patterns of ejaculates (P > 0.05); the mean values of VOL, VOLGEL, MOT, VIG, and CONCT were 149.1 ± 51.1 mL, 29.7 ± 10.0 g, 76.2% ± 9.5%, 3.3 ± 0.5, and 29.4 ± 19.5 × 10⁹ total sperm in the ejaculate, respectively. The prevalence rates of defects were 5.9% ± 2.6% for MAJDEF, 10.2% ± 4.0% for MINDEF, and 16.2% ± 5.5% for TDEF; all animals were classified as being sound for breeding. The assessed characteristics were similar to those observed in swine of commercial lineages and within the standards established by the Brazilian College of Animal Reproduction for the species.     

Effect of divergent selection for testosterone production on testicular morphology and daily sperm production in boars

The objective of this study was to characterize correlated responses in testicular morphology and daily sperm production to divergent selection for testosterone production. Duroc boars from high and low lines (HTL and LTL, respectively) divergently selected over 10 generations for testosterone production in response to a GnRH challenge followed by random selection were used. Testicular tissues were sampled from all available males of generation 20 (HTL, n = 46; and LTL, n = 13). Volume densities for Leydig cells, seminiferous tubules, and Sertoli cells were estimated along with sperm production. The HTL boars had greater volume densities of Leydig cells than did LTL (P < 0.01). Volume density of seminiferous tubules tended to differ between lines (P < 0.07), but Sertoli cell volume densities did not differ (P < 0.27). Sperm production traits, adjusted for age, did not differ significantly between lines. Body, testicular, and epididymal weights were recorded for boars from HTL (n = 82) and LTL (n = 44) from generations 20 and 21. After adjustment for BW, average paired testicular weights for HTL and LTL were 417 and 457 g (P < 0.01), respectively. Epididymal weights, adjusted for BW, were heavier for HTL (P < 0.01) than for LTL. To demonstrate that the selection lines still differed for testosterone production, lines were evaluated in generation 21. Endogenous testosterone production of the HTL (n = 54) and LTL (n = 44) testosterone production line averaged 49.0 ng/mL and 27.8 ng/mL (P < 0.01), respectively. Plasma FSH concentrations did not differ between lines (P < 0.30). Selection for testosterone production in response to a GnRH challenge was an effective method of changing testosterone concentrations, testicular size, epididymal weight, and volume density of Leydig cells. However, daily sperm production per gram of testes was unchanged. Based on the results of this study, selection for testosterone production is not recommended as a method of increasing sperm production in pigs.     

Elimination of testosterone and androstendione in the urine of boars in relation to the incretory function of the testes]

The elimination of testosterone and androstendion in the urine was tested in six sexually mature boars. The administration of chorionic gonadotropin to intact animals resulted in a marked, statistically significant, rise of the amounts of excreted testosterone and, in part of the cases, androstendion. The responses were individual. Bilateral orchidectomy caused a statistically highly significant decrease of the elimination of both steroids under study without pronounced adrenocortical compensation. The administration of the adrenocorticotropic hormone to castrated boars did not exert any significant influence on the excretion of the substances studied. The use of chorionic gonadotropin given to the castrated boars did not produce any significant changes in the elimination of hormones. It has been inferred that testosterone as well as androstendion in the urine of boars are almost exclusively of testicular origin and that the response of the values of both steroids to the administration of chorionic gonadotropin is specific after testicular incretion. The discussion concerns the importance of these findings for the evaluation of the incretion reserve of the testes and for the diagnosis of incretion hypogonadism in boars.     

Realized heritability estimates in boars divergently selected for testosterone levels(1,) (2)

SUMMARY: Data were collected from 1982 through 1992 from 100 sires and 891 Duroc boars. Testosterone production was measured from peripheral blood samples before (PRE) and after (POST) GnRH challenge. Additionally, data were collected on testes volume at 168 d (TVOL), days to 104 kg (DAYS104), number born alive (NBA) and backfat adjusted to 104 kg body weight (FAT). Realized heritabilities were estimated from the regression of response on cumulative selection differentials. Heritabilities for POST were .15 ± .18 and .24 ± .08 in the low and high lines, respectively. This compares with the estimate of .26 ± .21 from son-sire regressions. The regression of other traits on cumulative selection differentials can be viewed as realized correlated responses to selection. After 10 generations, the high line was approximately three times greater than the low line for both PRE and POST levels of testosterone. Although not significant, high line pigs required fewer days to reach 104 kg, had more backfat and larger testes than low line pigs. Litter size was significantly larger for high line than for low line. ZUSAMMENFASSUNG: Realisierte Heritabilit?tssch?tzungen von Divergenz für Testosteronspiegel selektierten Ebern Die Daten stammen aus dem Zeitraum 1982-1992 von 891 Duroc Ebern aus 100 Vatertieren. Testosteronproduktion wurde von peripheren Blutproben vor (PRE) und nach (POST) GnRH-Gaben gemessen. Zus?tzlich wurden Angaben über Hodenvolumen am Tag 168 (TVOL), Zeitraum bis 104 kg Lebendgewicht (DAYS104), Zahl lebend geborener (NBA) und auf 104 kg K?rpergewicht korrigierte Rückenspeckdicke (FAT) erhoben. Realisierte Heritabilit?tswerte wurden aus der Regression von Selektionserfolg auf kumulative Selektionsdifferenzen gesch?tzt. Heritabilit?t für POST waren 0,15 ± 0,18 und 0,24 ± 0,08 in der Minus- und in der Pluslinie. Aus Sohn-Vater-Regressionen ergab sich 0,26 ± 0,21. Die Regression anderer Eigenschaften auf kumulative Selektionsdifferenzen k?nnen als realisierte korrelierte Selektionserfolge betrachtet werden. Nach 10 Generationen hatte die Pluslinie etwa dreimal h?here PRE- und POST-Spiegel von Testosteron als die Minuslinie. Obwohl nicht signifikant, brauchten Schweine der Pluslinie weniger Tage bis 104 kg, waren fetter und hatten gr??ere Hoden als Schweine der Minuslinie. Die Wurfgr??e der Pluslinie war h?her als in der niedrigen Linie.     

Variation of the serum testosterone level in boars during 24 hours and during a period of several days]

Seven sexually mature boars were studied in two-hour intervals for 8 to 32 hours, as to the variation of testosterone levels in the blood plasma. Blood samples were obtained by means of a cannula inserted in the v. cava cranialis. The hormone level under study showed marked fluctuation. The coefficient of variation of testosterone concentration ranged from 12.7% to 35.2% in the individual animals and for the whole part of the study it was 33.0%. It appeared impossible to derive seriously any regular periodicity of testosterone concentration in boar blood in the 24-hour period from the analysis of the variation of the levels of the hormone in individual animals during the period under study. Further, the study revealed a marked fluctuation of testosterone levels in the blood plasma of twelve sexually mature boars in the course of several days' study. The coefficient of variation of testosterone concentration in individual animals ranged from 18.1% to 106.5%, reaching 77.0% for the whole part of study. The analysis of variance showed statistically significant differences of hormonal levels in individual boars in which the fluctuation of testosterone was studied in the 8- to 32-hour period as well as in several days' period. This proved the role of the animals' individuality in determining the concentration of testosterone in their blood. The discussion concerns the importance of these findings for the evaluation of the role of basal testosterone levels in the blood in classifying the incretion function of the gonads and in the diagnosis of incretion hypogonadism of boars.     

Effect of active immunization against GnRH on testosterone concentration,libido and sperm quality in mature AI boars

Background

The aim of the present study was to investigate the efficacy of the Improvac on testosterone concentration in blood serum, sexual behavior and sperm quality in matured AI boars. A total of nine Danish Landrace AI boars were included in the analysis.

Methods

The trial period lasted for 15 weeks and was divided into four periods: Control period: three weeks before vaccination; Period I – four weeks after first vaccination; Period II – four weeks after second vaccination, Period III – four weeks after third vaccination. Blood and sperm samples were collected at weekly intervals. Freshly collected sperm samples were analyzed.

Results

Testosterone concentration correlated with libido (r = 0.531; p < 0.001), volume of ejaculate (r = 0.324; p < 0.001) and the percentage of morphologically normal spermatozoa (r = 0.207; p < 0.05). Testosterone concentration rised significantly (p < 0.05) in 5–6 week of trial, e. i. after the first dose of Improvac and after this peak the level of testosterone further progressively decreased (p < 0.05).

Conclusions

Results from this study indicate that active immunization of sexually matured boars against GnRH has negative impact on testosterone concentration, sexual behavior, volume of ejaculate and total number of normal spermatozoa in ejaculate.     

Effects of vasectomy on fructose levels in the ejaculate of rams.

Fructose concentration was studied in the ejaculates of 20 intact and 19 vasectomised rams over a two year period. In intact rams the concentration ranged from 222-740 mg/100 ml of seminal plasma during the breeding season (October to December), with lower values (0-300 mg/100) during the rest of the year. In vasectomised rams the seasonal pattern was less marked with very high values (800-1260 mg/100 ml) as well as low values (0-20 mg/100 ml) being encountered during both the breeding and non-breeding seasons, indicating changes in accessory gland function.     

Endocrine and spermatogenic testicular function. 9. Correlations between plasma testosterone and morphometric parameters of the testis in boars of different ages]

Close, statistically fully secured correlations were found to exist in boars, aged between four and four-a-half as well as seven and nine months, between the testosterone content in the blood of the V. spermatica interna, on the one hand, and morphometric parameters essential to quantitative sperm production, on the other (testicular volume, volume of germinativum, overall length of tubules, diameter of tubules, and cell density of the germinal epithelium).     

Intratesticular administration of testosterone in the therapy of disorders of the quality of ejaculates in boars

The clinical effect of the bilateral intratesticular administration of a microcrystalline water suspension of testosterone was studied in ten boars of Duroc breed exhibiting semen quality disorders. The ejaculate quality disorders included separate or combined deviations of the values of sperm concentration (hypozoospermia to oligozoospermia), sperm activity (asthenozoospermia), or the occurrence of abnormal spermatozoa (teratozoospermia) from the spermiological standard. After intratesticular infiltration, all the criteria of spermiogram were completely restored in four cases and the boars could be returned to insemination use. A partial improvement of the spermiogram (the number of spermiological criteria with positive responses and the development of their values) without fully meeting all the requirements of the spermiological standard was recorded in four breeding boars. No positive response of ejaculate quality characteristics was obtained in two boars. As to the evaluated criteria of the spermiogram, sperm activity was the most frequent positively influenced parameter in the cases of idiopathic or combined asthenozoospermia, and the increased percentage of abnormal spermatozoa was the least frequent positively influenced parameter in the cases of idiopathic or combined teratozoospermia. It is supposed that the easily practicable methods of intratesticular infiltration with a microcrystalline testosterone suspension could expand the therapeutic possibilities available to veterinary andrologists in the treatment of ejaculate quality disorders in boars.     

Changes of fructose concentrations in seminal plasma and glucose and testosterone concentrations in blood plasma in rams over the course of a year

The present study was performed to examine seasonal changes in the fructose concentrations of seminal plasma and glucose and testosterone concentrations of blood plasma over the course of a year (from November 2004 to November 2005) using 5 Suffolk rams. Osmolality of the seminal plasma was also measured. The fructose concentrations in the seminal plasma increased as the breeding season approached, with the maximum in October (179.8 mg/dl) and the minimum in May (6.9 mg/dl), although there were no significant differences during the year. Osmolality of the seminal plasma in February (304 mOsm) was significantly (P<0.05) lower than in January (325 mOsm), July (327 mOsm), and August (325 mOsm). It was also significantly (P<0.05) lower in November (308 mOsm) than in January and August. The blood plasma glucose concentration in October (79.3 mg/dl) was significantly (P<0.05) higher than in January and February (43.2 and 43.7 mg/dl, respectively). The blood plasma testosterone (T) concentrations were significantly (P<0.05) higher in September (8.5 ng/ml) and October (10.2 ng/ml) than in other months. The fructose concentrations in the seminal plasma appeared to be related to the glucose and T concentrations in the blood plasma. These results show that fructose concentrations in the seminal plasma and blood plasma glucose and T concentrations tended to increase during the breeding season, with the highest concentrations in October.     

种公牛精清中睾酮含量与精液品质相关性探讨

本实验采用放射免疫分析法（ＲＩＡ）检测了种公牛精清中睾酮（Ｔ）含量２９头次，并对其相对应的每份精液进行了品质评定。结果表明，精清中睾酮含量平均为１４９．４９±１４１．９６ｎｇ／ｄｌ。在每头种公牛之间存在显著的个体差异，同一头种公牛，在不同的采精日期的同一时刻采精，其Ｔ含量也有显著差异，说明种公牛Ｔ的分泌具有脉冲性的特点，种公牛精清中Ｔ的含量与精液量、精子密度、活力、活率及畸形率均未见显著的相关性。