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.     

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.     

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.     

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。     

Effects of chronic gonadotropin-releasing hormone agonist treatment on serum luteinizing hormone and testosterone concentrations in boars.

Mature boars were subjected to chronic treatment with a gonadotropin-releasing hormone (GnRH) agonist, goserelin (D-Ser[But]6, Azgly-NH210), and serum luteinizing hormone (LH) and testosterone concentrations were measured. Ten sexually mature boars were randomly assigned to treatment (n = 5) or control (n = 5) groups. On day 0, boars were implanted sc (day 0) with 2 GnRH agonist implants (1 mg of GnRH/implant) or sham implants. Blood samples were collected at 12-hour intervals on days -2 and -1, at 6-hour intervals on days 0 through 4, and at 12-hour intervals on days 5 through 8. In addition, blood samples were collected at 15-minute intervals for 6 hours on days -1, 0, 4, and 8. Serum testosterone and LH concentrations were determined by radioimmunoassay. Maximal LH (7 +/- 1 ng/ml) and testosterone (26 +/- 3 ng/ml) concentrations were observed at 5 and 18 hours, respectively, after GnRH agonist treatment. Subsequently, LH and testosterone concentrations decreased to pretreatment values (0.3 +/- 0.1 ng/ml and 1.8 +/- 0.4 ng/ml, respectively) by 24 and 48 hours, respectively, after GnRH agonist implantation. Few differences in the characteristics of pulsatile LH release were observed between the groups. Testosterone and LH concentrations in samples collected at 6- and 12-hour intervals and pulsatile LH release did not change after sham treatment of control boars. Whereas previous reports indicated that chronic GnRH administration suppressed serum LH and testosterone concentrations in rams, rats, and dogs, our results indicate that chronic GnRH agonist treatment induced transitory increases, without subsequent suppression, in LH and testosterone concentrations in mature boars.     

Relationships of gonadotropins, testosterone, and cortisol in response to GnRH and GnRH antagonist in boars selected for high and low follicle-stimulating hormone levels

Considerable variation exists in the serum levels of gonadotropins in boars; this results in differential testicular function. Boars (Chinese Meishan, European White composite, and crosses of the two breeds) selected for high and low circulating FSH concentrations were used to define possible differences in pituitary sensitivity to GnRH and GnRH antagonist and gonadal and adrenal responses. After a 2-h pretreatment sampling period, boars were injected with GnRH or GnRH antagonist and repetitively sampled via jugular cannula for changes in serum concentrations of FSH, LH, testosterone, and cortisol. In response to varying doses of GnRH or GnRH antagonist, FSH, LH, or testosterone changes were not different in high- or low-FSH boars. Declines in LH after GnRH stimulation were consistently faster in boars selected for high FSH. Chinese Meishan boars had considerably higher cortisol concentrations than White composite boars (132.2 +/- 28.5 vs 67.4 +/- 26.8 ng/mL, respectively; P < .01). When select high- and low-gonadotropin Meishan:White composite crossbreds were sampled, cortisol levels were elevated but comparable between the two groups (126.5 +/- 13.7 vs 131.4 +/- 13.4 ng/mL, respectively). After GnRH antagonist lowered LH concentrations, administration of hCG resulted in increased testosterone and cortisol concentrations. Although testosterone concentrations remained high for 30 h, cortisol concentrations returned to normal levels within 10 h after hCG injection. The mechanism by which boars selected for high gonadotropins achieve increased levels of LH and FSH may not be due to differences in pituitary sensitivity to GnRH but to differences in clearance from the circulation.     

Serum testosterone levels and response to administration of chorionic gonadotropins in bovine hermaphrodites]

The concentration of testosterone in the blood and its response to administration of chorionic gonadotropin was examined in two bovine intersexes (testicular pseudo-hermaphroditism) and two control bulls without disorders in sexual differentiation. The levels of testosterone in the blood were markedly lower in both intersexes than in the control bulls. Both intersexes, unlike the control bulls, also showed a response of the blood testosterone level to the administration of chorionic gonadotropin. The conclusion is that in the given type of intersexuality the incretion function of the testes is mardedly deficient as to androgen production and functional hormonal reserve.     

种公猪营养与繁殖性能

营养与繁殖性能的关系越来越受到人们关注,而种公猪的繁殖性能对养猪生产至关重要。研究表明营养是影响种公猪繁殖性能的主要因素,营养缺乏使得种公猪繁殖性能低下。文中主要综述了能量、蛋白质与氨基酸、维生素、矿物质等营养素与种公猪繁殖性能关系以及种公猪的营养需要等。     

Effect of ACTH administration on biochemical and immune measures in boars

The effects of stress induced by adrenocorticotropic hormone (ACTH) on biochemical and immune changes in Swedish Landrace boars aged approximately 6-7 months were observed during ACTH administration and for 16 days after the cessation of treatment. Adrenocorticotropic hormone treated animals (n = 7) were given intravenously 10 microg/kg body mass of ACTH for 3 days. Control group of animals (n = 7) received intramuscularly 1 ml of sterile 0.9% saline. Total protein and globulin levels were significantly elevated during the induced stress period and for the next 16 days (P < 0.01 to P < 0.0001, respectively). Also, serum immunoglobulin IgG concentration was significantly elevated during and after ACTH injection (P < 0.001 to P < 0.0001). Adrenocorticotropic hormone treatment had no effect on serum albumin, IgA and IgM concentrations. Glucose concentration was significantly decreased on the second day of ACTH administration (P < 0.001) and on day 9 after treatment (P < 0.001). Calcium level was significantly decreased only for 24 h after the last ACTH dosage (P < 0.01). Also, serum phosphorus level was significantly decreased on the first (P < 0.05) and third (P < 0.001) days of ACTH challenge but remained unaffected after the cessation of ACTH treatment. It is concluded that the administration of ACTH to boars results in immune humoral and biochemical changes during stress and the post-stress period.     

Changes in lipid levels in the blood of pregnant sows]

Variations of plasma volume (PV) and variations of triglyceride, cholesterol, total lipid, beta-lipoprotein and phospholipid concentrations in the blood plasma were investigated in trials with ten sows, crossbreds of the White Thoroughbred and Landrace breeds, at the age of 2-3 years, kept on a defined diet; the trials were performed before the sows became pregnant and during their pregnancy (days 1-40, 41-60, 61-80, 81-100 and 101-120). The PV in nonpregnant sows is 9.8 +/- 0.33 1. Following a decrease to the values of 7.8 +/- 0.33 l (p less than 0.01) in the first 40 days of pregnancy the plasma volume increases in the successive periods and it makes 15.4 +/- 0.19 l at the end of pregnancy (p less than 0.001). Total lipaemia decreases during pregnancy from 2.80 +/- 0.054 in nonpregnant sows to 2.49 +/- 0.245 g per 1 in sows at the end of pregnancy. Cholesterol concentrations in the blood plasma also decrease from 2.48 +/- 0.53 in nonpregnant ones to 1.88 +/- 0.173 mmol per 1 (p less than 0.001) in sows at the end of pregnancy, beta-lipoprotein concentrations from 3.95 +/- 1.134 in nonpregnant ones to 3.47 +/- 0.199 g per l in sows on days of pregnancy 81-100 (p less than 0.05), phospholipid concentrations in the first 60 days of pregnancy from 1.62 +/- 0.079 before insemination to 1.29 +/- 0.05 mmol per l in sows of 41-60 day pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同佐剂GnRH疫苗主动免疫对公猪睾丸发育和血清睾酮的影响

为探讨铝胶佐剂与白油Span佐剂的GnRH疫苗对公猪睾丸发育和血清睾酮的影响,12头初生公猪随机分为GnRH疫苗铝胶佐剂免疫组和GnRH疫苗白油Span佐剂免疫组(下简称铝胶组和白油组).9周龄初免,17周龄加强免疫,25周龄屠宰.游标卡尺测量猪阴囊直径和睾丸大小,石蜡切片观察睾丸组织发育,ELISA法和放射免疫分析(RIA)法分别检测GnRH抗体水平和血清睾酮水平.结果表明,铝胶组与白油组GnRH抗体效价差异不显著(P0.05).铝胶组血清睾酮水平于17,21周龄(P＜0.05)和25周龄(P＜0.01)显著地低于白油组,阴囊直径,睾丸直径、横径、周长及睾丸血量均显著地低于白油组(P＜0.05).铝胶组与白油组猪睾丸曲精小管均出现不同程度的空泡化,白油组零星分布少量精子,铝胶组无精子产生.这表明在公猪免疫去势的效果上,辅以铝胶佐剂的GnRH疫苗比辅以白油Span佐剂的GnRH疫苗好.     

Effect of ACTH and CRH on plasma levels of cortisol and prostaglandin F2alpha metabolite in cycling gilts and castrated boars

The present study was designed to evaluate the effects of synthetic ACTH (1-24, tetracosactid) and porcine CRH on the plasma levels of cortisol and PGF2alpha metabolite in cycling gilts (n = 3) and castrated boars (n = 3). The experiments were designed as crossover studies for each gender separately. Each animal received, during three consecutive days; 1) ACTH (Synacthen Depot) at a dose of 10 microg/kg body weight in 5 ml physiological saline, 2) porcine CRH at a dose 0.6 microg/kg body weight in 5 ml physiological saline or 3) physiological saline (5 ml). The test substances were administered via an indwelling jugular cannula in randomized order according to a Latin square. The administration of ACTH to cycling gilts resulted in concomitant elevations of cortisol and PGF2alpha metabolite with peak levels reached at 70.0 +/- 10.0 and 33.3 +/- 6.7 min, respectively. Similarly, the administration of ACTH to castrated boars resulted in concomitant elevation of cortisol and PGF2alpha metabolite with peak levels reached at 60.0 +/- 0.0 and 20.0 +/- 0.0 min, respectively. Cortisol peaked at 20 min after administration of CRH in both cycling gilts and castrated boars with maximum levels of 149.3 +/- 16.5 nmol/l and 138.3 +/- 10.1 nmol/l, respectively. It can be concluded that administration of synthetic ACTH (tetracosactid) to pigs caused a concomitant elevation of cortisol and PGF2alpha metabolite levels in both cycling gilts as well as castrated boars. The administration of CRH to pigs resulted in an elevation of cortisol levels in both cycling gilts and castrated boars. Conversely, PGF2alpha metabolite levels were not influenced by the administration of CRH either in cycling gilts or in castrated boars.