Relationships of testicular iron and ferritin concentrations with testicular weight and sperm production in boars

The inverse relationship of testicular size and circulating follicle-stimulating hormone (FSH) concentrations has been documented, and accompanying this relationship is the change in color of the parenchymal tissue of the testes. Large testes (300 to 400 g) are pink to light red and small testes (100 g) are dark maroon with color gradations for weights in between. It was hypothesized that this color most likely represented an iron protein. Chromatographic analysis of testicular tissue indicated that the Fe was associated primarily with ferritin, and immunohistochemistry showed that Leydig cells were the primary location of ferritin storage within the testes. Concentrations of Fe and ferritin were higher in small testes and decreased as testes weight increased (P < 0.05). As testicular Fe concentrations increased, daily sperm production (DSP) and total DSP declined (P < 0.05). Genotyping six generations of Meishan x White composite boars (n = 288) for a quantitative trait locus that is indicative of elevated FSH and small testes in boars indicated that the Meishan genotype had elevated testicular iron concentrations and darker color in conjunction with reduced total DSP (P < 0.01). It is not thought the elevated iron concentrations affect testicular weights but are probably a result of elevated FSH and FSH inducement of Fe transport. The storage of Fe in Leydig cells may provide a reservoir of Fe for easy access by Sertoli and germ cells, but still provide a degree of protection to germ cells from ionic iron.     

Genetic parameters for testosterone production in boars

Data were collected in 1982 through 1989 from 66 sires and 358 Duroc boars. Testosterone production was measured from peripheral blood samples before (PRE) and after (POST) GnRH challenge. Additionally, data were collected on testes length at 168 d (TL168), testes width at 168 d (TW168), testes volume at 168 d (TVOL), birth weight (BWT), average daily gain (ADG), days to 104 kg (DAYS104), and backfat adjusted to 104 kg (FAT). Overall means for these traits were 24.6 ng.ml-1.h-1, 75.7 ng.ml-1.h-1, 12.3 cm, 11.6 cm, 422.0 cm3, 1.5 kg, .5 kg, 189.3 d, and 18.5 mm, respectively. Son-sire regressions were used to calculate genetic parameters. Heritabilities for PRE, POST, TL168, TW168, TVOL, BWT, ADG, DAYS104, and FAT were .37, .26, .33, .34, .33, .21, .42, .35, and 0, respectively. Moderately favorable genetic correlations were obtained for PRE and POST with growth measurements. Large positive genetic correlations were present for both PRE and POST with TL168, TW168, and TVOL, and testes measurements had large positive genetic correlations with growth traits. Selection for testes size or testosterone production should be equally effective. However, it seems that selection for testes size would result in larger changes in measures of growth than selection for testosterone. This study suggests that testes measurements are good predictors of both basal and challenge testosterone levels. Selection for increased testis size or increased testosterone levels would be expected to enhance growth.     

Effect of temperature and humidity on sperm morphology in duroc boars under different housing systems in Thailand

The aim of this study was to investigate the effect of season, temperature, humidity, age of the boar, and semen collection interval on sperm morphology in Duroc boars in Thailand, kept either in a conventional open air system (CONV) or in an evaporative cooling system (EVAP). In total, 1176 ejaculates from 110 sexually mature boars in six CONV herds and five EVAP herds were morphologically examined during a one-year period. Analysis of variance was applied to the data. Minor differences in the sperm morphology traits analyzed were found between the housing systems. There was a significant seasonal effect (two-month periods) on the percentage of morphologically normal spermatozoa (normal1), morphologically normal spermatozoa including spermatozoa with distal cytoplasmic droplets (normal2), proximal cytoplasmic droplets (prox), and sperm head abnormalities (P相似文献   

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.     

Correlated responses in growth, carcass, and meat quality traits to divergent selection for testosterone production in pigs

The objective of this project was to characterize changes in growth, carcass yield, and meat quality traits in castrates and gilts in response to divergent selection for testosterone production. In generation 21, endogenous testosterone concentrations in Duroc boars of the high (HTL) and low (LTL) testosterone lines averaged 49.0 and 27.8 ng/mL (P < 0.01), respectively. Eight LTL and 10 HTL boars were used to sire 29 LTL and 33 HTL litters. To remove the effects of inbreeding, these same boars were mated to females of a Large White x Landrace composite (WC) to generate 11 WC by LTL litters (WLT) and 23 WC by HTL litters (WHT). Castrates and gilts were then allotted to LTL (n = 53), HTL (n = 61), WLT (n = 102), and WHT (n = 101) for testing. Growth and carcass traits analyzed included days to 114 kg (D114), ADG, backfat adjusted to 114 kg (ABF), LM area adjusted to 114 kg and predicted percent lean (PPL). Fat-O-Meater data collected were adjusted fat depth (AFD), adjusted loin depth, and percent lean. Meat quality traits characterized at 24 h postmortem included marbling score, percent lipid, pH, drip loss, color score, and Minolta L*, a*, and b*. Data were analyzed with a mixed model including fixed effects of line, mating type (purebred or crossbred), sex, and the random effect of sire nested within line. All possible interactions among fixed effects were tested. The HTL had fewer D114 (P < 0.05), greater ADG (P < 0.01), greater ABF (P < 0.01), and lower PPL (P < 0.01) than LTL. The WHT and WLT did not differ for D114, ADG, or ABF. The WHT had smaller LM area adjusted to 114 kg (P < 0.05) and greater drip loss (P < 0.05) than WLT. The WLT had lower adjusted loin depth (P < 0.05) than LTL and HTL. The LTL and HTL had greater subjective scores for marbling (P < 0.05) compared with WLT and WHT. The least squares mean for percent lipid for HTL and LTL was 4.00. The WHT had greater means for L*, a*, and b* (P < 0.05) than WLT. Pigs selected for increased testosterone production grew faster and produced fatter carcasses than pigs selected for decreased testosterone. Changes in growth, carcass yield, and meat quality traits were detected in castrates and gilts in response to divergent selection for testosterone production.     

Effects of breed and ejaculate volume on sperm morphology and semen parameters of boars

The aim of the study was to determine the relation between the semen quality, frequency of sperm defects, sperm dimensions and shape, and the ejaculate volume of Large White and Landrace boars. A total of 648 ejaculates collected from 31 Large White and 30 Landrace boars were divided into three groups according to the criterion of the ejaculate volume. In this study Landrace boars produced ejaculates with higher volume, sperm concentration, and total numbers of spermatozoa than Large White boars. Landrace boars also showed a lower frequency of sperm with morphological abnormalities (P < 0.05). Landrace boars sperm had larger heads, which were by 0.15 μm longer, and by a larger perimeter and area (P < 0.05). Landrace boar spermatozoa also had a longer flagellum and were generally larger and by 2.07 μm longer than Large White boar sperm (P < 0.05). Significant differences were also found in the shape of sperm of the two breeds (P < 0.05). Landrace boars sperm had more elongated heads, and the ratio of head size to flagellum length was lower than in Large White boars sperm (P < 0.05). Sperm from ejaculates with low volume had a shorter flagellum and a greater head length/flagellum length ratio than sperm from medium- and high-volume ejaculates (P < 0.05).     

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.     

Effects of social interactions on empirical responses to selection for average daily gain of boars

Effects of social interactions on responses to selection for ADG were examined with records of 9,720 boars from dam lines (1 and 2) and sire lines (3 and 4) provided by Pig Improvement Company. Each line was analyzed separately. Pens contained 15 boars. Average daily gains were measured from about 71 to 161 d of age and BW from 31 to 120 kg. Models included fixed effects of contemporary groups and initial test age as a covariate and random direct genetic (a), social genetic (c), social environmental (ce), and litter (lt) effects. Estimates of direct heritability with model 1 (the full model with a, c, ce, and lt) were 0.21, 0.28, 0.13, and 0.15 for lines 1 to 4. Estimates of heritability of social effects were near zero. Estimates of total heritable variance were 55, 52, 38, and 96% of phenotypic variance for lines 1 through 4. Empirical responses to selection with model 1 were calculated using the parameter estimates from model 1. For response of 1 genetic SD for both components (a and c), the proportions of expected total gain due to social effects (with economic weights of 1 and pen size-1 = 14) were 54, 28, 65, and 65% for the 4 lines. Genetic superiorities of the top 10% of boars were calculated for boars ranked using reduced models, but with EBV calculated using the full model (model 1). Average total breeding values (ETBV = EBV(a)+14EBV(c)) for the top 10% of boars selected with model 1 were 74.08, 94.26, 31.79, and 92.88 g for lines 1 through 4, respectively. For rankings based on model 2 (a, ce, and lt), but EBV calculated with model 1, average total breeding values for the top 10% were 68.15, 94.03, 7.33, and 84.72 g with empirical correlated responses for genetic social effects from selection for direct effects of 0.93, 1.89, -2.19, and 3.52 g for lines 1 to 4.     

A new preparation protocol for measurement of testicular sperm production

In studies of male reproductive toxicity, measuring daily sperm production is a quite important criterion. However, the accuracy of the values measured by the basic protocol is still controversial. In order to enhance the homogeneity of countable testicular sperm/spermatid heads, this report introduces a new enzymatic method with a subsequent detergent treatment. The testis of rat was firstly homogenized in phosphate-buffered saline. The homogenate (buffer mix) was then treated with collagenase and trypsin, and then sodium dodecyl sulfate (SDS) was added to produce detergent-resistant sperm/spermatid heads (detergent mix). After examination by hemocytometer, the coefficient of variation (CV) of the number of sperm/spermatid heads was compared with that obtained from the buffer mix. In addition, a MicroCell chamber was applied to the examination, and the CV was compared with other cases. In both examinations, homogeneity was improved by the detergent mix preparation. Counting with the hemocytometer showed an increased number of sperm/spermatid heads compared with that of the buffer mix (P<0.001), and the CV was decreased (P<0.05). In addition, when the MicroCell chamber was applied, the numbers increased about 3-hold compared with that of the buffer mix (P<0.001). The CV of the detergent mix was 23.7%, while that of the buffer mix was 38.9%. These results clearly demonstrate that the new preparation protocol generated in this study can provide more actual and accurate values when measuring daily sperm production.     

Seasonal changes of testicular weight, sperm production, serum testosterone, and in vitro testosterone release in Korean ring-necked pheasants (Phasianus colchicus karpowi)

To study the biology of reproduction of male Korean ring-necked pheasants kept under natural conditions of temperature and photoperiod, testicular weight, serum testosterone concentrations, testosterone release from the luteinizing hormone (LH)-stimulated testis in vitro and sperm production were measured. Significant changes associated with seasonal cycles were found. Testis weight decreased dramatically in August, remained low until February, rapidly increased from March to high levels to June, and decreased subsequently. Serum testosterone concentrations remained little from August until February, but increased sharply in March to reach the highest levels in April. Thereafter, the concentrations decreased significantly from June. The testosterone release was low from August to February, increased abruptly in March to reach the highest levels in May, and showed rapid decrease thereafter. Sperm production decreased to nondetectable levels from August to February, increased markedly in March, reached a peak in May, and sharply decreased thereafter. Thus, the pheasants breed from late March to late June. These results indicate that the Korean ring-necked pheasant, under natural conditions, exhibits characteristics of a seasonal cycle in reproduction.     

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)     

Experimentally induced testicular alterations in boars: hormonal changes in mature and peripubertal boars

Eleven sexually mature boars and 10 peripubertal boars were used to study the effects of elevated testicular temperature on plasma hormonal levels. The scrotum of the boars was covered with a textile-aluminium foil insulation device for 100 h. Insulation of the scrotum in the peripubertal boars took place at an age of 100 days. Blood samples were drawn 3 times daily for 12 days in the mature boars, starting 3 days before scrotal insulation. In the peripubertal boars, blood sampling was performed once a day for 11 days, starting the first day of scrotal insulation. During scrotal insulation, the plasma levels of testosterone, oestradiol-17 beta and oestrone sulphate decreased continuously in the mature boars. After removal of the scrotal insulation device there was a continuously increase, back to normal levels of oestradiol-17 beta and oestrone sulphate. The plasma levels of testosterone showed an immediate rise of brief duration after removal of the device in 5 of the boars, while in the other 6 boars the rise in testosterone levels came 4 days after removal and lasted for 3 days. In the peripubertal boars, there were no significant differences in the hormone levels between the experimental and control animals during and after scrotal insulation. However, the decrease in testosterone concentration over time, during scrotal insulation, was significant within the experimental group.     

Effect of bilateral vasectomy on testosterone levels in the seminal and blood plasmas of boars]

In two sexually mature boars subjected to bilateral vasectomy the content of testosterone was followed in the semen and blood plasma prior to the operation and in the course of 26 days after the operation. In the third boar only the operation without actual vasectomy as the control was made to eliminate the possible effect of narcosis and of the surgical stress. Bilateral vasectomy induced an average decrease in the initial levels of testosterone in the semen plasma of the first and second animal by 63.24% and 47.67% respectively, and 47.17% and 56.46% respectively in the blood plasma. In the control boar no analogous post-operation drop of testosterone concentration in the semen plasma was observed, the content of testosterone in the blood plasma decreased over the followed period on an average only by 14.38%. The results imply that bilateral vasectomy in boars results, in the first followed month after the surgical procedure, in a decrease of semen and plasma testosterone, which proves that the operation under investigation affects testicular incretion.     

Effect of sperm concentration in an ejaculate on morphometric traits of spermatozoa in Duroc boars

The experimental material consisted of 75 ejaculates collected form 8 Duroc boars. The ejaculates were divided into three groups according to sperm concentration in an ejaculate. An ejaculate was obtained from each boar monthly and it was used to make microscopic preparations to examine spermatozoa morphology. In each preparation morphometric measurements were taken of fifteen randomly selected spermatozoa characterized by normal morphology. The following measurements of spermatozoa were taken: length and width of the spermatozoa head, head area, length of the flagellum, perimeter of the spermatozoon head and total spermatozoon length. The results were used to calculate indicators of spermatozoa morphology. Moreover, assessments were made of frequency of morphological defects to isolate spermatozoa with primary and secondary abnormalities following the Blom classification system. It was found that the concentration of spermatozoa in the ejaculate influenced the morphometric characteristics of spermatozoa. Ejaculates with low sperm concentrations are characterized by larger spermatozoa as compared to ejaculates with high sperm concentrations. However, sperm concentration in the ejaculate does not much influence the shape of spermatozoa.