Evaluation of spermatological parameters in ochratoxin A--challenged boars

Exposure to certain mycotoxins has been proved to contribute to fertility problems in pigs. Although ochratoxin A (OA) is one of the most common naturally occurring mycotoxins, there is little data concerning the possible effects of this toxin on sperm quality of boars.After a 4-week control period, animals were given 20 microg OA per os daily for 6 weeks, followed by a 9-week withdrawal period. Serum and seminal plasma were monitored for OA with enzyme-linked immunosorbent assay (ELISA). Spermatozoal motility was measured at 0, 24, 48, 72 and 96 h, and ejaculation volume, initial viability and progressive motility were recorded. Samples of testis and epidydimidis were evaluated histologically. Viability, initial forward motility, and motility after 24h storage were significantly reduced in the experimental group in the withdrawal period only. There were no major histological differences in number and morphology of Leydig cells and epydidimal structures between experimental and control boars. Results of the present study demonstrate that OA may affect sperm production and boar semen quality only after a lag period. Further research is required to elucidate the possibility of a direct or indirect interaction between the toxin and germ cells (spermatogonia).     

Seminal plasma damages sperm during cryopreservation, but its presence during thawing improves semen quality and conception rates in boars with poor post-thaw semen quality

To determine the effects of seminal plasma during and after cyopreservation on post-thaw sperm functions in semen from poor freezability boars, seminal plasma was removed immediately after collection, and sperm was subjected to cooling and freezing. Removal of seminal plasma did not significantly affect post-thaw sperm motility in good freezability boars; however, in boars with poor freezability, it increased post-thaw motility relative to control sperm cooled with seminal plasma (64.5+/-3.4% vs. 30.9+/-3.1%, P<0.01). Freezing sperm without seminal plasma increased both loss of the acrosome cap (37.5+/-1.6% vs. 18.4+/-2.8%, P<0.01) and expression of a 15 kDa tyrosine-phosphorylated protein (capacitation marker) in thawed sperm relative to controls; the addition of 10% (v/v) seminal plasma to the thawing solution significantly suppressed both changes and increased conception rate to AI (70% vs. 9% in the control group, P<0.05). In conclusion, our novel cryopreservation and thawing method increased the success of AI with frozen-thawed porcine semen, particularly from boars with poor post-thaw semen quality.     

Lipid profiles of sperm and seminal plasma from boars having normal or low sperm motility

Sperm plasma membrane lipids have an important role to play in determining membrane fluidity and sperm motility. The objective of the present study was to determine whether there are differences in the lipid and fatty acid (FA) composition of boar sperm and seminal plasma in the ejaculates of boars having different sperm motilities. Semen was collected from two groups of boars having normal (> 60%; n = 53) or low (< 60%; n = 53) motility sperm and the semen was evaluated for motility, morphology and vitality. The semen was then centrifuged to separate the sperm from the seminal plasma and both were kept at −20 °C until analyzed for lipid content and FA profile by gas chromatography. Total antioxidant status (TAS) of seminal plasma was determined using a commercial kit. There were differences (P ≤ 0.05) in sperm total lipids, cholesterol, saturated fatty acids (SFA), phospholipids, n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the ratio of n-6:n-3 PUFA between boars with normal and low motility sperm. Total lipids, cholesterol, phospholipids, PUFA, DHA and n-3 PUFA were positively correlated with sperm motility, viability, normal morphology and normal plasma membrane. In contrast, SFA and the ratio of n-6: n-3 PUFA were negatively correlated (P ≤ 0.05) with sperm motility, viability, normal morphology and normal plasma membranes. The TAS of seminal plasma from boars having normal motility sperm was higher (P ≤ 0.05) than that of boars having low motility sperm and TAS was positively correlated (P = 0.0001) with sperm motility, viability, normal morphology and normal plasma membranes. In summary, differences in sperm motility were related to n-3 PUFA content in the sperm plasma membrane and extracellular antioxidants in seminal plasma which protect sperm plasma membranes from lipid peroxidation during periods of oxidative stress.     

Liquid storage of miniature boar semen.

The effects of liquid storage at 15 degrees C on the fertilizing ability of miniature pig semen were investigated. Characterization of ejaculated semen from 3 miniature boars was carried out. Semen volume and pH were similar among these boars. In one of the boars, sperm motility was slightly low, and sperm concentration and total number of sperm were significantly lower than in the others (P < 0.01). Seminal plasma of the semen was substituted with various extenders (Kiev, Androhep, BTS and Modena) by centrifugation and semen was stored for 7 days at 15 degrees C. Sperm motility was estimated daily at 37 degrees C. For complete substitution of seminal plasma, Modena was significantly more efficient than the other extenders (P < 0.001) in retaining sperm motility. Semen from each of the 3 miniature boars that had been stored for 5 to 7 days at 15 degrees C in Modena was used for artificial insemination of 15 miniature sows. The farrowing rates were 100, 100 and 60%, and litter sizes were 6.4 +/- 1.5, 5.8 +/- 0.8 and 5.0 +/- 1.0 for each boar semen, respectively. The boar that sired the smallest farrowing rate was the same one that showed lower seminal quality with respect to sperm motility, sperm concentration and total number of sperm. These results suggest that miniature boar semen can be stored for at least 5 days at 15 degrees C by the substitution of seminal plasma with Modena extender.     

Influence of seminal plasma on the fecundity of chicken spermatozoa

This study was undertaken to investigate the influence of seminal plasma on the fecundity of chicken sperm. Sperm diluted with either incubated seminal plasma (5 or 37 degrees C for 24 h) or seminal plasma from incubated whole semen (5 or 37 degrees C for 24 h) had lower fertility levels and motility scores than sperm diluted in either fresh seminal plasma or a synthetic diluent. The number of sperm with damaged membranes increased with seminal plasma derived from 37 degrees C incubation. The depressive effect of incubated seminal plasma on semen fertility was eliminated by microfiltering .(0.22 mum) the seminal plasma either before or after incubation. Filtration of seminal plasma was only effective in eliminating the depressive effect on sperm motility when filtering was done after incubation. Filtration of seminal plasma reduced the percentage of damaged sperm in all treatments. It can be concluded that there are factors in seminal plasma that are deleterious to the fecundity of chicken spermatozoa and they may be derived from degenerating sperm and/or various fluids, cells and debris collected with the semen during manual semen collection.     

Dialysis of boar semen prior to freezing-thawing: its effects on post-thaw sperm characteristics

Low-molecular weight components of the seminal plasma have a detrimental effect on sperm function. The present study was undertaken to evaluate the effect of the removal of low-molecular weight components by dialysis on sperm characteristics prior to and after freezing. Semen, collected from 5 boars, was extended in Kortowo-3 extender (K-3, Poland) and cooled for 3h (control non-dialysis) or dialyzed for 5h in semi-permeable dialysis bags of 12-14kDa molecular weight cut-off prior to freezing. The semen samples were diluted in lactose-hen egg yolk-glycerol extender (lactose-HEY-G) or lactose-lyophilized lipoprotein fractions-glycerol extender (lactose-LPFo-G), packaged into aluminum tubes and frozen in a controlled programmable freezer. Pre-frozen and frozen-thawed spermatozoa were evaluated for motility, plasma membrane (SYBR-14 and propidium iodide) and acrosome integrity, mitochondrial function (Rhodamine 123) and ATP content. The results of the study showed that dialysis significantly improved the sperm characteristics prior to freezing. Dialysis enhanced (P<0.05) post-thaw sperm motility, plasma membrane integrity and mitochondrial function, but had no significant effect (P>0.05) on recovery of spermatozoa with intact acrosomes. Furthermore, dialyzed spermatozoa exhibited higher (P<0.05) ATP content compared with the control after freezing-thawing. Consistent inter-boar variability was detected mainly in dialyzed semen following freezing-thawing. These results indicated that the improvement in sperm quality characteristics prior to freezing and the post-thaw sperm recovery were due to the removal of low-molecular weight components from the seminal plasma. It can be suggested that dialysis is effective in improving the post-thaw quality of boar spermatozoa and has also great practical importance in improving the protocols for cryopreservation of semen. Dialysis may also contribute to a better understanding of different mechanisms underlying cryo-induced damage to boar spermatozoa.     

Comparison of the semen characteristics of Fengjing, Meishan and Yorkshire boars

Semen characteristics of Chinese Fengjing, CHinese Meishan and American Yorkshire boars were examined. Samples were collected from 24 boars: 6 Fengjing, 12 Meishan and 6 Yorkshire. Three semen characteristics and 6 biochemical evaluations of semen or seminal plasma were analyzed. The whole semen parameters measured were gelatinous (gel) and gel-free volume and progressive motility. Fengjing boars were higher in gel volume than Meishan (P < 0.05) but not Yorkshire boars (P > 0.25), while Yorkshire boars were higher than Meishan boars in gel volume (P < 0.10). The gel-free volume was higher in Yorkshire and Fengjing boars than Meishan boars (P < 0.10), but Fengjing gel-free volumes did not differ from Yorkshire gel-free volumes (P > 0.80). However, the only difference detected for progressive motility was between Fengjing and Meishan boars (78.5 vs 74.5%; P < 0.10). Sperm concentration was higher in Meishan than Yorkshire boars (P < 0.01) although these breeds did not differ from Fengjing boars (P > 0.18). The biochemical messurements made were fructose, galactose, inositol, total carbohydrate and total protein in seminal plasma and pH in gel-free semen. Fengjing boars had higher concentrations of galactose in seminal plasma than Meishan or Yorkshire boars (P < 0.05), while Meishan seminal plasma had higher galactose concentrations than Yorkshire seminal plasma (P < 0.10). Fructose, inositol and total carbohydrate concentrations were all higher in Fengjing and Meishan seminal plasma than Yorkshire seminal plasma (P < 0.05). Fengjing seminal plasma had higher levels of inositol than Meishan seminal plasma (769 vs 566 mg/100 ml; P < 0.10). Furthermore, Fengjing and Meishan semen had similar fructose and total carbohydrate concentrations (P > 0.80). The pH level and total protein concentration did not differ among the 3 breeds (P > 0.30). This study indicated that breed differences were detected for several seminal parameters, although no single breed had consistantly higher values for all the parameters measured.     

Blood Serum and Seminal Plasma Selenium,Total Antioxidant Capacity and Coenzyme Q10 Levels in Relation to Semen Parameters in Men with Idiopathic Infertility

In this case–control study, we aimed to evaluate the serum and seminal plasma levels of Selenium (Se), total antioxidant capacity (TAC), and Coenzyme Q10 (CoQ-10) and determine their relationship with sperm concentration, motility, and morphology in men with idiopathic infertility. A total of 59 subjects were enrolled in the study. Forty four patients were diagnosed with idiopathic male infertility and had abnormal sperm parameters, and 15 subjects had normal sperm parameters with proven fertility. Serum Se, semen Se, and semen TAC levels were significantly different in the fertile and infertile groups (p?<?0.01, p?<?0.001, and p?<?0.001, respectively). However, serum TAC, serum, and seminal plasma CoQ-10 levels did not differ between fertile and infertile groups. When the levels of the measured parameters were compared in serum and seminal plasma, serum levels of Se were found to be correlated positively with the semen levels in all subjects included into the study (N?=?59) (r?=?0.46, p?<?0.01). A relationship was found between neither serum and semen levels of TAC nor between serum and semen levels of CoQ-10. Correlations among measured serum and semen parameters with sperm parameters demonstrated that both the serum and semen levels of Se were correlated positively with spermatozoa concentration, motility, and morphology. Additionally, seminal plasma levels of TAC correlated positively with all these sperm parameters. On the other hand, seminal plasma levels of CoQ-10 correlated only with sperm morphology but not with concentration or motility. No relationship was observed between serum levels of TAC or serum levels of CoQ-10 and sperm parameters. In conclusion, serum and seminal plasma Se deficiency may be a prominent determinant of abnormal sperm parameters and idiopathic male infertility. Measurement of serum Se levels may help determine nutritional status and antioxidant capacity in infertile patients, which may help distinguish those patients who will benefit from supplementation therapy.     

Effects of single nucleotide polymorphisms in the 5'-flanking region of heat shock protein 70.2 gene on semen quality in boars

This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season.     

Epididymal sperm from the African buffalo (Syncerus caffer) can be frozen successfully with AndroMed and with Triladyl but the addition of bovine seminal plasma is detrimental

Numerous diseases are carried and can be transmitted from the African buffalo (Syncerus caffer) to livestock. Buffaloes free of specific diseases (BFSD) are thus in demand amongst game farmers. Current BFSD derive from a small genetic pool and hence there is a special interest in bringing new genetic material into such herds. In this study epididymal sperm from 16 mature African buffalo bulls was frozen with Triladyl and AndroMed extender (Minitüb, Tiefenbach, Germany) with and without addition of bovine seminal plasma. Post-thaw motility, longevity and acrosomal integrity were compared. In all but one animal, post-thaw motility was higher, although not always significant, if sperm was frozen with Triladyl than with AndroMed. Seminal plasma was detrimental to the post-thaw motility. Neither semen extender nor seminal plasma had an influence on post-thaw acrosomal integrity. It can be concluded that bovine seminal plasma at a concentration of 10% is detrimental rather than beneficial for the post-thaw motility of African buffalo sperm. Even though being inferior AndroMed does, however, have the advantage that it is a defined semen extender and therefore clearly has a lower risk of contamination.     

Do sperm contribute to the buffering capacity of steelhead trout (Oncorhynchus mykiss) semen?

The motility of salmonid sperm is pH-sensitive and the buffering capacity of the seminal plasma is low. The objective of the present study was to determine the extent to which sperm contribute to the buffering capacity of whole steelhead (Oncorhynchus mykiss) semen. To determine the buffering capacity, semen and seminal plasma samples were titrated with HCl and pH measurements taken at 1-2 min. The buffering capacity of semen was not different from that of seminal plasma over the pH range 7.5 to 8.5 and was approximately 15% to 20% less over the range 6.0 to 7.0. Comparable results were obtained for the semen and seminal plasma of the chinook salmon (Oncorhynchus tshawytscha). To assess whether the intracellular environment could influence the buffering capacity, the effects of cell disruption with n-butanol and Triton X-100 (TX-100) were determined. Over the pH range 7.5 to 8.5, the presence of n-butanol or TX-100 resulted in a doubling of the buffering capacity of the semen; TX-100, but not n-butanol, increased semen buffering capacity over the pH range 6.0 to 7.0. To determine whether the sperm's intracellular compartment might contribute to the buffering capacity over a longer duration, semen and seminal plasma samples were acidified with HCl and the pH measured over several hours. These data suggest that intact sperm contribute no more than about 25% to the buffering capacity of whole semen. The buffering capacity of steelhead semen and seminal plasma were comparably and modestly temperature sensitive. The results suggest that the sperm may contribute to the buffering capacity of the semen over a physiological pH range, however, if so, the effect is relatively small.     

The removal of the seminal vesicles from the boar and the effects on the semen characteristics.

A technique is described for the removal of the seminal vesicles from the boar. The operation was carried out on twelve animals and six of the animals were subsequently trained for semen collection. The seminal plasma from the boars after surgery compared with normal litter mates had a more watery consistency and did not form the characteristic gelduring ejaculation. The sperm concentration was 49% lower while the total reduction of sperm number ejaculate was 78% in the experimental animals, but the ratio of living to dead spermatozoa remained unchanged. The concentrations of citrate and protein were significantly depressed in the seminal plasma of the animals after surgery and the pH increased; the osmolarity remained unchanged. In semination of gilts with the semen from experimental boars revealed no significant loss of fertility compared with the normal controls. Animals slaughtered up to 17 months after surgery showed no regeneration of the seminal vesicles.     

Relationship between Lipids Levels of Serum and Seminal Plasma and Semen Parameters in 631 Chinese Subfertile Men

Objective

This prospective study was designed to investigate the relationship between lipids levels in both serum and seminal plasma and semen parameters.

Methods

631 subfertile men were enrolled. Their obesity-associated markers were measured, and semen parameters were analyzed. Also, seminal plasma and serum TC, TG, HDL and LDL and serum FFA, FSH, LH, total testosterone (TT), estradiol (E2) and SHBG levels were detected.

Results

Seminal plasma and serum TG, TC and LDL levels were positively related to age. Serum TC, TG and LDL were positively related to obesity-associated markers (P < 0.001), while only seminal plasma TG was positively related to them (P < 0.05). For lipids levels in serum and seminal plasma, only TG level had slightly positive correlation between them (r = 0.081, P = 0.042). There was no significant correlation between serum lipids levels and semen parameters. However, seminal plasma TG, TC, LDL and HDL levels were negatively related to one or several semen parameters, including semen volume (SV), sperm concentration (SC), total sperm count (TSC), sperm motility, progressive motility (PR) and total normal-progressively motile sperm counts (TNPMS). Moreover, seminal plasma TG, TC, LDL and HDL levels in patients with oligospermatism, asthenospermia and teratozoospermia were higher than those with normal sperm concentration, motility or morphology. After adjusting age and serum LH, FSH, TT, E2 and SHBG levels, linear regression analysis showed that SV was still significantly correlated with seminal plasma LDL (P = 0.012), both of SC and TSC with seminal plasma HDL (P = 0.028 and 0.002), and both of PR and sperm motility with seminal plasma TC (P = 0.012 and 0.051).

Conclusion

The abnormal metabolism of lipids in male reproductive system may contribute to male factor infertility.     

Motility and fertility of alginate encapsulated boar spermatozoa

Ejaculated boar spermatozoa are vulnerable to cold shock. Prolonged storage of boar spermatozoa at low temperatures reduces survival rate, resulting in a bottleneck for the extension of artificial insemination in pig husbandry. This study evaluated whether alginate microencapsulization processing can improve the longevity of boar spermatozoa stored at 5 degrees C and the fertility of microencapsulated spermatozoa in vivo. Sperm-rich fraction semen from three purebred boars were concentrated and microencapsulated using alginate at 16-18 degrees C, and then were stored at 5 degrees C. Following storage for 1, 3 and 7 days, the microcapsule was taken out to assess sperm release under 37 degrees C incubation with or without 110 rpm stirring. The percentage of sperm released from microcapsules with 110 rpm stirring was higher than without stirring (81 versus 60%) after 24h of incubation. In another experiment, semen was also microencapsulated to evaluate the sperm motility. The motility of spermatozoa was assessed at 10 min, 8, 24, 32, 48, 56 and 72 h following incubation at 37 degrees C for nine consecutive days. The fertility of the free and microencapsulated semen was assessed by inseminating sows, and the reproductive traits (conception rate, farrowing rate, and litter size) were recorded. The motility of encapsulated spermatozoa was significantly higher than that of free semen after 8h incubation at 37 degrees C after storing for over three days (P<0.05). No significant difference existed in conception rate, farrowing rate, and litter size between the microencapsulated and non-encapsulated semen after four days of storage. In conclusion, microencapsulation can increase the longevity of boar spermatozoa and may sustain in vivo ova fertilization ability.     

Comparison of semen characteristics,sperm freezability and testosterone concentration between Duroc and Yorkshire boars during seasons

This study was carried out to investigate the effects of Duroc and Yorkshire boars and seasons influencing semen characteristics, frozen-thawed sperm viability and serum testosterone concentration. Yorkshire boars produced higher semen volume compared to Duroc boars among seasons. However, sperm concentration did not differ significantly between Duroc and Yorkshire boars among seasons. Sperm motility of frozen-thawed sperm in Yorkshire boars was higher than in Duroc boars in spring and summer. Normal acrosome of frozen-thawed sperm in Yorkshire boars was higher than in Duroc boars in winter. Serum testosterone concentrations in Duroc and Yorkshire boars were higher in spring than in summer, autumn and winter. Serum testosterone concentrations in spring and summer were higher in Yorkshire boars than in Duroc boars. In conclusion, when serum testosterone concentrations were higher in Duroc and Yorkshire boars among seasons, semen volume, sperm concentration and frozen-thawed sperm viability were higher.     

Effect of centrifugation and partial removal of seminal plasma on equine spermatozoal motility after cooling and storage

The objective of this study was to determine if centrifugation and partial removal of seminal plasma would improve spermatozoal motility in semen from stallions whose whole ejaculates have poor tolerance to cooling and storage. Stallions were divided into two groups (n = 5/group) based on the ability of their extended semen to maintain spermatozoal motility after cooling and storage. Group 1 stallions ("good coolers") produced semen in which progressive spermatozoal motility after 24 h of cooling and storage was reduced by < or = 30% of progressive motility prior to storage. Group 2 stallions ("poor coolers") produced semen in which progressive spermatozoal motility after 24 h of cooling and storage was reduced by > or = 40% of progressive motility prior to storage. The sperm-rich portion of each ejaculate was divided into 4 aliquots. Two aliquots underwent standard processing for cooled transported semen and were examined after 24 and 48 h of cooling and storage in an Equitainer. The remaining two aliquots were diluted 1:1 with semen extender, then centrifuged at 400 x g for 12 min at room temperature. After centrifugation, approximately 90% of the seminal plasma was removed, and the sperm pellet was resuspended in extender to a final concentration of 25 to 50 x 10(6) sperm/mL. These aliquots were then packaged as for the non-centrifuged aliquots and examined after 24 and 48 h of storage. The spermatozoal motion characteristics in fresh semen and after 24 and 48 h of cooling and storage was determined via computer-assisted semen analysis. Centrifugation and partial removal of seminal plasma increased the percentage of progressively motile spermatozoa and limited the reduction in progressive spermatozoal motility of "poor cooling" stallions after 48 h of cooling and storage. Results of this study indicate that centrifugation and partial removal of seminal plasma is beneficial for stallions whose ejaculates have poor tolerance to cooling and storage with routine semen dilution and packaging techniques, especially if the semen is stored for > 24 h.     

Semen changes in boars after experimental infection with porcine reproductive and respiratory syndrome (PRRS) virus

Eleven boars seronegative to porcine reproductive and respiratory syndrome virus (PRRSV) were trained for semen collection: five boars were inoculated intranasally with 6 x 10(6)TCID(50)/ml of PRRSV (Group A); four boars were inoculated intranasally with 6 x 10(4)TCID(50)/ml (Group B); and two boars were used as uninfected control (Group C). Semen samples were collected at 7-d intervals from 49 d prior to experimental inoculation with PRRSV to 70 d after inoculation, and were examined for sperm volume, sperm concentration, sperm morphology, sperm motility and for the presence of PRRSV. The infection in boars was demonstrated by the reisolation of PRRSV from the serum of all inoculated boars. Rectal temperatures and general health of the boars were clinically normal throughout the trial. Differences were observed in the quality of semen collected from boars after experimental infection with PRRSV. This infection induced a significant decrease in sperm motility and in spermatozoa with normal acrosomes. Of the semen samples tested for virus isolation in swine alveolar macrophages PRRSV was only isolated in 1 boar from Group B. The virus was detected in an additional semen sample in Group A by the production of an antibody titer in a biological assay. All attempts to detect PRRSV by RT-PCR in semen samples were unsuccessful. Nevertheless, from our study it is possible to suggest that the PRRSV can occasionally be transmitted in the semen during the initial phase of the disease.     

Identifying useable semen

The "predictors of useable semen" used in most commercial AI centers provide a very conservative estimate of the relative fertility of individual boars. Furthermore, the relatively high sperm numbers used in commercial AI practice (usually >3 x10(9) total sperm per dose of extended semen) usually compensate for reduced fertility, as can be demonstrated in some boars when lower numbers of sperm are used for AI. Differences in relative boar fertility are also masked by the widespread use of pooled semen for commercial AI in many countries. However, the need to continually improve the efficiency of pork production, suggests that commercial AI practice should involve increased use of boars with the highest genetic merit for important production traits. Necessarily, this must be linked to the use of fewer sperm per AI dose, fewer inseminations per sow bred, and hence more sows bred by these superior sires. In turn, this requires improved techniques for evaluating semen characteristics directly related to the fertilization process, such as IVM-IVF assays, analysis of seminal plasma protein markers, more discriminatory tests of sperm motility and morphology, with the goal of identifying high-index boars whose fertility is sustained when low numbers of sperm are used for AI. This paper reviews the current status of laboratory-based boar semen evaluation techniques that meet these criteria.     

Arylsulfatases are present in seminal plasma of several domestic mammals.

Mammalian spermatozoa and seminal plasma both contain high levels of arylsulfatases (AS), enzymes that remove sulfate from sulfated glycoconjugates. In ejaculated semen of boars, 85% of AS was found in seminal plasma whereas only 13% was found in spermatozoa. A comparable distribution of AS between spermatozoa and seminal plasma was observed in other domestic mammals. The presence of AS in seminal plasma was not due to leakage from spermatozoa because sperm cells had intact acrosomes and plasma membranes after their separation from seminal plasma, and because 84% of the acrosomal marker enzyme hyaluronidase was retained in washed spermatozoa. Spermatozoa in boar semen diluted with Beltsville Thawing Solution (BTS) deteriorated faster during storage at 17 degrees C than spermatozoa stored in BTS without seminal plasma. This suggests that seminal plasma has a deleterious effect on mammalian spermatozoa. We propose that (1) sulfated glycoconjugates stabilize sperm plasma membranes; (2) AS present in seminal plasma contribute to the deterioration of spermatozoa by desulfating these glycoconjugates; and (3) AS present in seminal plasma could well play a role in sperm capacitation.     

Effects of dietary supplementation with polyunsaturated fatty acids and antioxidants on biochemical characteristics of boar semen

The aim of this study was to investigate the effect of providing a supplement containing polyunsaturated fatty acids and antioxidants (PROSPERM) on the biochemical characteristics of boar semen. Two sexually mature boars were fed a standard diet with PROSPERM (250 g daily) for a 24-week period. Ejaculates collected prior to supplementation were used as the control. Semen quality and biochemical parameters were analyzed. The dietary supplementation enhanced sperm characteristics, including the percentage of spermatozoa with intact plasma membrane and osmotic resistance of the acrosomal membrane. Higher production of malondialdehyde was concurrent with increased activity of superoxide dismutase in the seminal plasma and spermatozoa after 8 weeks of supplementation. These changes were accompanied by a high content of total protein and low-molecular antioxidants of the seminal plasma. It was observed that PROSPERM supplementation enhanced the survivability of boar spermatozoa during storage in a standard semen extender supplemented with lipoprotein fractions, isolated from hen egg yolk or ostrich egg yolk, at 5 degrees C and 16 degrees C. These results indicate that PROSPERM supplementation of boars had a beneficial effect on the biological characteristics of the spermatozoa, which could be useful for semen preservation at different temperatures.