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At least 73 records · Page 4Linked to original sources
PubMed1978

Boar malpha-acrosin. Purification and characterization of the inital active enzyme resulting from the conversion of boar proacrosin to acrosin.

The preparation of highly purified malpha-acrosin is described. Purification was achieved by controlled activation of partially purified proacrosin, followed by gel chromatography over Sephadex G-100 at pH 3.0. The final malpha-acrosin preparation resulted in a single protein band with a molecular weight of 49,000 as determined by sodium dodecyl sulfate-disc gel electrophoresis. Disc arginine naphthylamide hydrolyzing band with a relative migration of 0.39 malpha-acrosin catalyzed the hydrolysis of synthetic substrates containing arginine and lysine, but not phenylalanine. Although calcium ions were not required for enzymatic activity, the addition of calcium chloride stimulated the activity through an increased substrate affinity and an increased maximal velocity. Polyamines stimulated the maximal velocity of the reaction, but were without effect on the substrate affinity. malpha-Acrosin was inhibited by lima bean, ovo-mucoid, and seminal plasma proteinase inhibitors. Diisopropyl fluorophosphate and 1-chloro-3-tosylamide-7-amino-L-2-heptanone treatment resulted in an irreversible inhibition, while L-arginine, benzamidine, and p-aminobenzamidine were competitive inhibitors with respect to substrate. These properties of malpha-acrosin are very similar to those previously reported for mbeta-acrosin and suggest that the portion of the molecule lost during the conversion of malpha-acrosin to mbeta-acrosin contributes little to the topography of either the active site or regulatory sites of the enzyme.

Acrosin↗
PubMed1996

Differential pituitary and gonadal function of Chinese Meishan and European white composite boars: effects of gonadotropin-releasing hormone stimulation, castration, and steroidal feedback.

Considerable breed differences exist in concentrations of gonadotropins between Chinese Meishan boars and meat-type crossbred boars of European origin. To define mechanisms that might be responsible, sensitivity to GnRH stimulation, hormonal clearance, and gonadal pituitary feedback effects were monitored in two experiments. In the first trial, jugular catheters were placed into mature Meishan (n = 7) and white composite boars (n = 8). Boars were repetitively sampled after administration of two doses of GnRH (150 and 1500 ng/kg BW) a week apart. Before administration of GnRH, FSH was greater in Meishan boars (554 +/- 50 vs. 102 +/- 8 ng/ml, p < 0.01). Both breeds responded with increases in FSH, LH, and testosterone; but concentrations of gonadotropins in Meishan boars were increased for a greater duration than in white composite boars. By 160 min after GnRH administration, gonadotropins were declining in white composite boars. Maximal plasma concentrations of FSH after GnRH stimulation were greater with the higher GnRH dosage than with the lower (1058 +/- 113 vs. 730 +/- 70 in Meishan and 184 +/- 40 vs. 141 +/- 14 ng/ml in white composite boars). In the second trial, boars were assigned to three groups related to their circulating FSH concentrations: European white composite boars (FSH = 100 ng/ml), Meishan boars with low FSH (FSH = < 500 ng/ml), and Meishan boars with high FSH (FSH > 750 ng/ml; n = 5 per breed group). Boars were cannulated and repetitively sampled during three protocols: 1) low GnRH stimulation (15 ng/kg BW), 2) pre- and postcastration, and 3) steroidal treatment (0.5 mg testosterone propionate and 20 micrograms estradiol cypionate/kg BW; then 24 days later, a 20-strength low-dosage steroid treatment). At the low GnRH stimulation, LH and testosterone concentrations were increased but FSH concentrations were not altered. Rate of increase of FSH and decline of testosterone concentrations were not different between the three treatment groups after castration. Castration levels of FSH were maintained and further increased with time. Rates of reduction in FSH concentration after gonadal steroidal stimulation were not different between breed groups, but Meishan boars escaped the exogenous steroid suppression earlier than white composite boars (p < 0.01). Differences in concentrations of gonadotropins in Meishan and white composite boars of European origin seem to be at the pituitary level of control and not related to gonadal factors.

Animals↗
PubMed1989

Development of the seminiferous tubules after neonatal hemicastration in the boar.

Development of the prepubertal seminiferous tubules of the right testis was characterized morphometrically every 14 days from 10 to 122 days of age in intact boars (I) and boars hemicastrated (HC) on Day 10 of life from two herds (Trial 1 and Trial 2). Comparisons were made between the remaining testis of Group HC boars and one testis in Group I boars. By 38 days of age seminiferous tubule length in Group HC boars was double (P less than 0.0001) that in Group I boars. Seminiferous tubule length did not differ between trials within treatments. The diameter of the seminiferous tubule was similar in Group HC and I boars but was greater (P less than 0.05) in Trial-1 than Trial-2 boars from Day 80 to 122 of life. Relative mass (mass of tissue/body mass) of Sertoli cells became 2-fold greater (P less than 0.0001), in Group HC than in one testis of Group I boars by 38 days of age and this difference was maintained throughout the experimental period. The relative mass of Sertoli cells was greater (P less than 0.05) in Trial-1 than Trial-2 boars within each treatment between 80 and 122 days of age. The relative mass of gonocytes was similar for all groups and treatments of boars. By 122 days of age the relative mass of spermatogenic cells was greater (P less than 0.05) in Group HC than in one testis of Group I boars and greater (P less than 0.01) in Trial-1 than Trial-2 boars within each treatment. Onset of spermatogenesis was first observed at 80 and 94 days of age in boars in Groups HC and I, respectively. Development of seminiferous tubule lumen was first observed at 94 and 108 days of age in boars in Groups HC and I respectively. Seminiferous tubule lumen, taken as a measure of fluid secretion of the Sertoli cells, occupied a greater (P less than 0.01) portion of seminiferous tubule in Trial-1 than Trial-2 boars within each treatment at the end of the experimental period. It is concluded that neonatal hemicastration of boars rapidly caused a compensatory seminiferous tubule elongation apparently due to Sertoli cell proliferation and an earlier onset of spermatogenesis. However, the gonocytes do not proliferate until they transform into spermatogonia.

Animals↗
PubMed2001

Detection and duration of porcine reproductive and respiratory syndrome virus in semen, serum, peripheral blood mononuclear cells, and tissues from Yorkshire, Hampshire, and Landrace boars.

Because transmission of porcine reproductive and respiratory syndrome virus (PRRSV) can occur through boar semen, it is important to identify persistently infected boars. However, even for boars given the same PRRSV strain and dose, variability in the duration of viral shedding in semen has been observed, suggesting that host factors are involved in PRRSV persistence. To determine whether there are host genetic factors, particularly litter and breed differences related to the persistence of PRRSV, 3 litters from 3 purebred swine breeds were used for this study. It was also determined whether PRRSV could be detected for a longer period of time in serum, semen, or peripheral blood mononuclear cells (PBMC) and if PRRSV could still be detected in tissues after these antemortem specimens were PRRSV negative for a minimum of 2-3 weeks. Three Hampshire, 3 Yorkshire, and 2 Landrace PRRSV-naive boars were obtained and inoculated intranasally with a wild-type PRRSV isolate (SD-23983). All boars within each breed were from the same litter, and litters were within 9 days of age. Serum and PBMC were collected twice weekly from each boar and analyzed for the presence of PRRSV by virus isolation and the polymerase chain reaction (PCR). Serum was also used to obtain virus neutralization titers and enzyme-linked immunosorbent assay S/P values. Semen was collected twice weekly from 7 of 8 boars and analyzed by PCR. After all specimens were PRRSV negative for a minimum of 2-3 weeks, each boar was euthanized, and 21 tissues plus saliva, serum, feces, and urine were collected. All postmortem specimens were evaluated by virus isolation. Specimens that were PRRSV negative by virus isolation were then evaluated by PCR. The mean number of days (+/-SD) for the duration of PRRSV shedding in semen was 51+/-26.9 days, 7.5+/-4.9 days, and 28.3+/-17.5 days for Landrace, Yorkshire, and Hampshire boars, respectively. Because of small sample sizes and large SDs, the differences in duration of PRRSV shedding in semen between breeds were not considered significant. However, the trend suggested that Yorkshire boars were more resistant to PRRSV shedding in semen than were Landrace boars, requiring further investigation using a larger numbers of boars. PRRSV was detected for a longer period in semen than in serum or PBMC in 4 of 7 boars. Viremia could be detected for a longer period in serum than in PBMC in 6 of 8 boars. After a minimum of 2-3 weeks of PRRSV-negative serum, semen, and PBMC, PRRSV could still be detected in the tonsil of 3 of 8 boars by virus isolation, indicating that boars still harbor PRRSV within the tonsil even though antemortem specimens are PRRSV negative.

Animals↗
PubMed1988

The influence of duration of photoperiod and hemicastration on growth and testicular and endocrine functions of boars.

Yorkshire boars were used to evaluate the influence of duration of photoperiod and hemicastration on growth and testicular and endocrine functions. At 10 wk of age, 5 hemicastrate (HC) and 5 intact (I) boars were assigned to either 8 or 16 hr of light daily until 6 mo of age. Body weights were recorded biweekly throughout the experiment. Venous cannulae were placed in all boars at 6 mo of age, and serum was collected at 30 min intervals from 0800 to 2000 hr. Gonadotropin releasing hormone (GnRH) was infused at 2000 hr (50 micrograms) and at 2030 hr (250 micrograms), and samples of serum were collected until 2400 hr. The following day, all boars were castrated, and the weights and sperm content of the testes and epididymides were determined. At castration, all pigs were given implants containing testosterone. Two weeks later, pigs were again canulated, and serum was obtained at 15 min intervals for 2 hr. Growth of boars was not significantly affected by duration of photoperiod or number of testes. Duration of photoperiod did not affect weight or sperm content of testes or epididymides. Hemi-castrated boars had greater testicular (P less than .01) and capita-corpora (C-C) epididymal weights (P less than .05) and more testicular and C-C sperm (P less than .01) per testis. Neither average concentrations of luteinizing hormone (LH) nor number and amplitude of pulses of LH were affected by photoperiod treatment. However, HC boars had greater average concentrations of LH (P less than .05) than I boars (.71 +/- .05 vs .52 +/- .05 ng/ml). Hemicastrated boars in 16 hr light daily had greater concentrations of FSH in serum (P less than .05) than 8I, 8HC, and 16I boars. Intact and HC boars had similar concentrations of prolactin (PRL) and testosterone. Similarly, concentrations of PRL and testosterone were not affected by duration of photoperiod. Secretion of LH and testosterone after treatment with GnRH was not significantly affected by duration of photoperiod. In general, HC boars released more LH in response to GnRH treatment than I boars. Concentrations of LH were greater (P less than .05) in HC than I boars at .5, 1, 2, and 3 hr after GnRH and tended (P less than .10) to be elevated at 1.5, 2.5, 3.5 and 4 hr after GnRH. The FSH response to GnRH was greater (P less than .05) for 16HC than 8I, 8HC, or 16I boars.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2000

PGF2alpha facilitates the training of sexually active boars for semen collection.

The objective was to determine the effects of PGF2alpha on the training of sexually active boars (i.e., boars experienced with natural mating) to mount an artificial sow for semen collection. Boars were moved to a semen collection pen twice weekly for 4 wk. After entering the pen, boars received im treatment with 10 mg PGF2alpha (n = 7) or 2 mL deionized water (n = 7). Boars were classified as trained when after a successful collection, the animals mounted the artificial sow and allowed semen collection on the next scheduled day without first receiving an injection of PGF2alpha or deionized water. The semen from 6 of 7 PGF2alpha-treated boars and 2 of 7 control boars was collected during the first exposure to the artificial sow (P < .03). After 4 training sessions, 7 of 7 PGF2alpha-treated boars and 4 of 7 controls were successfully trained (P < .05). The number of false mounts (mounting artificial sow but not allowing semen collection) per session was lower (P < .07) for PGF2alpha-treated boars (.6 +/- 1.0), compared to boars receiving deionized water (3.9 +/- 1.0) or trained boars receiving no treatment (3.4 +/- .7). Reaction time (elapsed time after entering collection pen until the start of ejaculation) was lower (P < .04) for PGF2alpha-treated boars (267.4 +/- 63.4 sec), compared to boars treated with deionized water (628.4 +/- 98.3 sec) or boars receiving no treatment (440.4 +/- 46.4 sec). In summary, use of PGF2alpha facilitated the training of sexually active boars to mount an artificial sow for semen collection.

Animals↗
PubMed2000

Effect of boar contact on follicular development and on estrus expression after weaning in primiparous sows.

Boar contact can induce ovarian activity, advance estrus and stimulate estrous behavior in sows. High amounts of boar contact can, however, suppress estrous behaviour. The present study with primiparous sows was designed to compare sows that had contact with a teaser boar during detection of estrus, with sows that had no boar contact at all. Number of sows detected in estrus within 9 d after weaning, onset and duration of estrus, follicular dynamics and timing of ovulation were studied. Boar contact increased the number of sows that ovulated and showed estrus from 14 of 47 to 24 of 47 (P < 0.05). Average timing of ovulation was later for sows with boar contact (165 h vs 150 h after weaning). Duration of estrus, detected without a boar, was similar in the two groups. For the sows with boar contact, duration of estrus detected with a boar was longer than estrus detected without a boar (56 vs 38 h; P < .01). Follicular dynamics were not affected by boar contact; boar contact only increased the number of sows with ovulation. Ovulatory sows showed a larger increase in follicular diameter (P < 0.01) from weaning to Day 4 after weaning (from 2.3 to 5.4 mm) than anovulatory sows (from 2.5 to 4 mm). Anovulatory sows did not show follicular growth after Day 4. It is concluded that boar contact can increase the number of sows that ovulate and show estrus after weaning. Estrous behavior does not seem to be suppressed by contact with a teaser boar, compared to sows without boar contact.

Animals↗
PubMed2000

PCR detection and evidence of shedding of porcine circovirus type 2 in boar semen.

An experimental study was conducted to evaluate the potential presence of porcine circovirus type 2 (PCV2) in the semen of infected boars. Four mature boars were inoculated intranasally with PCV2 isolate LHVA-V53 propagated on PK15 cells. Two boars inoculated with the supernatant of noninfected PK15 cells were kept as controls. Serum samples were collected from all boars at 4, 7, 11, 13, 18, 21, 25, 28, 35, and 55 days postinoculation (dpi) and from the four PCV2-infected boars at 90 dpi. Samples were tested for the presence of antibodies to PCV2 by an indirect immunofluorescence assay and for the presence of PCV2 DNA by PCR and nested PCR. Semen samples were collected from all six boars at 5, 8, 11, 13, 18, 21, 25, 28, 33, and 47 dpi and tested for the presence of PCV2 DNA by a nested PCR assay. Antibodies to PCV2 could be detected as early as 11 dpi in one boar, and all four infected boars were found positive for PCV2 antibodies by 18 dpi. Thereafter all infected boars remained positive for antibodies to PCV2 until 90 dpi. Analysis of serum samples by nested PCR demonstrated the presence of PCV2 DNA as early as 4 dpi in three of four infected boars. Serum samples from all infected boars were positive for PCV2 DNA from 11 dpi until 35 dpi but were negative at 90 dpi. PCV2 DNA was detected as soon as 5 dpi in the semen of two infected boars and intermittently thereafter in the semen of all four infected boars. The semen of two infected boars was positive for PCV2 DNA at 47 dpi. Following infection, PCV2 DNA can be detected in semen concurrently with the presence of PCV2 DNA and antibodies in the serum. The present study suggests that PCV2 may be shed intermittently in the semen of infected boars.

Animals↗
PubMed1995

Growth performance, carcass characteristics, and sensory attributes of boars administered porcine somatotropin by sustained-release implant for different lengths of time.

We investigated the effect of sustained-release implant administration of porcine somatotropin (pST) (4 mg/d) to male pigs for different lengths of time before slaughter. Crossbred white boars were assigned to six groups (n = 10/ group); B0, non-implanted boars; B6, boars implanted from 22 to 28 wk of age; B12, boars implanted from 16 to 28 wk of age; B18, boars implanted from 10 to 28 wk of age;C0, non-implanted castrates; and C18, castrates implanted from 10 to 28 wk of age. Castration was at 65 d of age. All pigs were slaughtered at 28 wk of age, and measures of offal and carcass components were recorded. Loin chops were collected for sensory evaluation. During the trial the pigs were maintained in individual pens with ad libitum access to water and a 19% CP corn-soybean meal diet containing 1.08% calculated lysine. Although pST reduced feed intake in castrates (P < .01), the effect in boars was nonsignificant. Slaughter weight was increased in a linear (P < .04) manner with length of pST treatment of boars, and slaughter weights of castrates given pST were greater (P < .01) than those of control castrates. The product of the changes in feed intake and gain resulted in greater efficiency of gain in pST-treated pigs than in control pigs (P < .01). A linear effect (P < .06) of length of pST treatment on trimmed lean cut weights of boars was noted. The weights of trimmed lean cuts produced by castrates treated for 18 wk with pST and boars treated for 12 or 18 wk were similar. Boars given pST for 18 wk had improved (P < .10) boar taint scores compared with untreated boars. Boars and castrates given pST for 18 wk had a similar rates of gain and weights of trimmed lean cuts. Efficiencies of gain were greater in pST-treated boars and castrates than in untreated boars, which were superior to untreated castrates in efficiency of gain.

Analysis of Variance↗