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Pronuclear formation in starfish eggs inseminated at different stages of meiotic maturation: correlation of sperm nuclear transformations and activity of the maternal chromatin.

Changes in sperm nuclei incorporated into starfish, Asterina miniata, eggs inseminated at different stages of meiosis have been correlated with the progression of meiotic maturation. A single, uniform rate of sperm expansion characterized eggs inseminated at the completion of meiosis. In oocytes inseminated at metaphase I and II the sperm nucleus underwent an initial expansion at a rate comparable to that seen in eggs inseminated at the pronuclear stage. However, in oocytes inseminated at metaphase I, the sperm nucleus ceased expanding by meiosis II and condensed into chromosomes which persisted until the completion of meiotic maturation. Concomitant with the formation and expansion of the female pronucleus, sperm chromatin of oocytes inseminated at metaphase I enlarged and developed into male pronuclei. Condensation of the initially expanded sperm nucleus in oocytes inseminated at metaphase II was not observed. Instead, the enlarged sperm nucleus underwent a dramatic increase in expansion commensurate with that taking place with the maternal chromatin to form a female pronucleus. Fusion of the relatively large female pronucleus and a much smaller male pronucleus was observed in eggs fertilized at the completion of meiotic maturation. In oocytes inseminated at metaphase I and II, the male and female pronuclei, which were similar in size, migrated into juxtaposition, and as separate structures underwent prophase. The chromosomes in each pronucleus condensed, intermixed, and became aligned on the metaphase palate of the mitotic spindle in preparation for the first cleavage division. These observations demonstrate that the time of insemination with respect to the stage of meiotic maturation has a significant effect on sperm nuclear transformations and pronuclear morphogenesis.

Animals↗

Cervical versus intrauterine insemination of ewes using fresh or frozen semen diluted with aloe vera gel.

This study was conducted at Belen de Escobar, Argentina, in March and April 1987. Experimental work on synchronization of estrus, deep-freeze conservation of ram semen and small fertility trials involving cervical and intrauterine (i.u.) insemination methods was undertaken. A total of 80 Corriedale ewes were used in seven insemination trials. Insemination trials were grouped into two experimental groups for comparison of 1) frozen semen diluted with an experimental extender and a control diluent inseminated cervically or i.u. in synchronized/superovulated ewes and 2) cervical insemination of fresh diluted or frozen semen in ewes inseminated at natural estrus or in ewes that were synchronized/superovulated. An overall ovulation rate of 8.7 +/- 0.5 was obtained by using a superovulatory regimen consisting of 3 mg Norgestomet implants and a total dose of 18 mg follicle stimulating hormone-pituitary (FSH-P). Numbers of ova recovered per ewe following superovulation ranged from 4.3 to 5.4. In experimental Group I, fertilization rates improved when laparoscopic intrauterine AI was used compared with cervical insemination (P<0.05). Fertility rates of i.u. and cervical insemination of frozen semen diluted with the experimental extender showed satisfactory fertilizing capacity. In experimental Group II, a lower number of fertilized ova were recovered from ewes inseminated with frozen semen (P<0.02), irrespective of their estrus manipulation.

Journal Article↗

Split ejaculate insemination with and without the addition of kallikrein.

48 couples with primary sterility and a therapy-resistant male factor (oligoasthenozoospermia, asthenozoospermia) were subjected to a split ejaculate insemination therapy with and without addition of kallikrein. In all men, in vitro stimulation of sperm motility by kallikrein was possible. 468 inseminations were performed in 341 ovulatory cycles according to the BBT and the cervical score. To the sperm-rich fraction of the split ejaculate physiological saline or physiological saline containing pancreatic kallikrein in a final concentration of 5 units/ml was added and inseminated alternatively over another cycle for a period of one year. The conception optimum was around the 7th insemination cycle. 11 conceptions were obtained after split insemination with kallikrein and 6 conceptions after split insemination without kallikrein. Conception rate was 35%, abortion rate 18%. The sex ratio showed 8 healthy girls to 4 healthy boys. Within the oligoasthenozoospermic group a conception rate of 28% was obtained, whereas the conception rate of the asthenozoospermic group was 43%. In the latter, more than the double number of conceptions were achieved with kallikrein addition. Kallikrein addition showed a beneficial effect particularly in ejaculates with less than 30% progressively motile spermatozoa. The investigation shows the usefulness of split ejaculate inseminations. Furthermore, addition of kallikrein to the ejaculate for the purpose of insemination may be beneficial particularly in patients with therapy-resistant asthenozoospermia.

Adult↗

Effect of cervical and vaginal insemination with liquid semen stored at room temperature on fertility of goats.

The effect of vaginal and cervical deposition of liquid semen stored at room temperature on the fertility of goats was tested in a field trial in which 217 Norwegian Dairy goats aged between 6 months and 7.5 years from 14 farms were inseminated after natural oestrous. Cervical insemination with 200 x 10(6) spermatozoa resulted in 25-day non-return and kidding rates of 87.0 and 78.0%, and vaginal insemination gave 85.5 and 74.3%, respectively. There was no significant difference between the cervical and vaginal inseminations (P = 0.59 for the 25-day non-return and P = 0.40 for the kidding rates). Farm had a significant effect on the 25-day non-return rate (P = 0.03) but not on the kidding rate (P = 0.07). There were no significant differences between the fertility rates for different bucks (P = 0.36 for the 25-day non-return and P = 0.15 for the kidding rates). Fertility results after vaginal insemination were encouragingly high. Vaginal insemination is a simple, less costly and time consuming technique compared to others, also bringing into focus the animal welfare aspects of the artificial insemination procedure. As the final goal is to establish a technique that could be applied similarly on a large scale by all farmers, vaginal insemination must be considered as a method that would simplify the use of liquid buck semen in Norway.

Animals↗

Effects of different artificial insemination techniques and sperm doses on fertility of normal mares and mares with abnormal reproductive history.

The effects of different artificial insemination (AI) techniques and sperm doses on pregnancy rates of normal Hanoverian breed mares and mares with a history of barrenness or pregnancy failure using fresh or frozen-thawed sperm were investigated. The material included 187 normal mares (148 foaling and 39 young maiden mares) and 85 problem mares with abnormal reproductive history. Mares were randomly allotted into groups with respect to AI technique (routine AI into the uterine body, transrectally controlled deep intracornual AI ipsilateral to the preovulatory follicle, or hysteroscopic AI onto the uterotubal junction ipsilateral to the preovulatory follicle), storage method of semen (fresh, frozen-thawed), AI volume (0.5, 2, 12 ml), and sperm dose (50 x 10(6) or 300 x 10(6) progressively motile sperm (pms) for fresh semen and 100 or 800 x 10(6) frozen-thawed sperm with >35% post-thaw motility). The mares were inseminated once per cycle, 24 h after hCG administration when fresh semen was used, or 30 h for frozen-thawed semen. Differences in pregnancy rates between treatment groups were analyzed by Chi-squared test, and for most relevant factors (insemination technique, mare, semen, and stallion) expectation values and confidence intervals were calculated using multivariate logistic models. Neither insemination technique, volume, sperm dose, nor mare or stallion had significant effects (P > 0.05) on fertility. Type of semen, breeding mares during foal heat, and an interaction between insemination technique, semen parameters, and mares did have significant effects (P < 0.05). In problem mares, frozen semen AI yielded significantly lower pregnancy rates than fresh semen AI (16/43, 37.2% versus 25/42, 59.5%), but this was not the case in normal mares. In normal mares, hysteroscopic AI with fresh semen gave significantly (P < 0.05) better pregnancy rates than uterine body AI (27/38, 71% versus 18/38, 47.3%), whereas in problem mares this resulted in significantly lower pregnancy rates than uterine body AI (5/15, 33.3% versus 16/19, 84.2%). Our results demonstrate that for problem mares, conventional insemination into the uterine body appears to be superior to hysteroscopic insemination and in normal mares, the highest pregnancy rates can be expected by hysteroscopic insemination.

Animals↗

Lambing rates and litter sizes following intrauterine or cervical insemination of frozen/thawed semen with or without oxytocin administration.

Intrauterine insemination by laparoscopy is required to achieve acceptable lambing rates in ewes when using frozen semen but the procedure has evoked welfare concerns. Oxytocin has been used to dilate the cervix as a means of accessing the uterus during conventional cervical insemination, but its effect on fertility is not well documented. Three hundred crossbred ewes were synchronised in estrus and randomly allocated to one of three insemination procedures using frozen/thawed semen containing 400 x 10(6)/ml progressively motile sperm: single cervical (0.2 ml), multiple cervical (4 x 0.05 ml) or laparoscopic (0.05 ml per uterine horn). The effects of each insemination procedure on lambing rate (percentage of treated ewes lambing) and litter size (lambs per ewe lambing) were tested with and without oxytocin (10 IU given i.m.) prior to fixed-time insemination. Oxytocin did not permit complete cervical penetration in any ewes and neither lambing rate nor litter size was influenced by the number of inseminations. Lambing percentages were 69 and 42 (P < 0.01) for the laparoscopic and cervical insemination methods, respectively, and oxytocin reduced these to 58 (NS) and 10 (P < 0.001) percent, respectively. Corresponding litter sizes for ewes not receiving oxytocin were 1.91 and 1.51 and for those receiving oxytocin, 1.83 and 1.41 (laparoscopic versus cervical, P < 0.02). Thus, in the absence of complete cervical penetration at insemination, 10 IU oxytocin decreased the number of ewes lambing but had no effect on their litter size.

Animals↗

Low dose insemination in cattle with the Ghent device.

A new artificial insemination device for semen deposition near the uterotubal junction (UTJ) in cattle (Ghent device) was developed at Ghent University (Belgium). In this study, UTJ insemination of dairy cows with the Ghent device was compared with the conventional insemination technique to evaluate the effect on pregnancy rates after insemination with different doses of semen. In each of three field trials, the cows (n=795, 659, 360) and heifers (n=253, 182, 231) were randomly assigned to receive 12 million sperm deposited in the uterine body using conventional techniques (control) or a reduced sperm dose (RSD) deposited in the same manner as the control or bilateral deposition near the uterotubal junction using the Ghent device (Ghent). Sperm dosages for RSD and Ghent inseminations were 8, 4, and 2 million sperm for field trials 1-3, respectively. In the multivariable analysis, the pregnancy rates were significantly affected by the parity of the cow (p</=0.008) in each of the three trials, by the sire (p=0.014, 0.009) in trials 1 and 3, and by the inseminator (p<0.001) in trial 2. In none of the trials were the pregnancy rates significantly affected by the insemination technique, the order of insemination (first, second, or third), the breed of the bull or the dosage sensitivity of the bull. In conclusion, neither sperm dosage nor site of semen deposition influenced pregnancy rates in the present study.

Analysis of Variance↗

Embryo production from superovulated cattle following insemination of sexed sperm.

Two trials were conducted to ascertain fertilization rate, embryo quality and numbers of transferable embryos in superovulated heifers and cows inseminated with sexed sperm. Inseminates contained 2 x 10(6), 10 x 10(6) or 20 x 10(6) total sperm enriched for the X- or Y-chromosome ( approximately 90%) by flow cytometry/cell sorting. Non-sexed inseminates contained 40 x 10(6) total sperm. Donors in each trial were allocated to one of each of the bulls included in that study. Each donor was inseminated with frozen/thawed sperm from the same bull for each treatment in successive courses of superstimulation with twice daily i.m. injections of FSH for 4 d. Heifers and cows were inseminated 12 and 24 h after visually observed standing estrus in Trial 1. In Trial 2, a single timed inseminate was used 70-72 h following PGF(2alpha). Ova/embryos were collected non-surgically 7-7.5 d after insemination. In both trials, fewer ova were fertilized with sexed versus non-sexed treatments and with 2 x 10(6) sexed sperm compared to higher doses (P < 0.05). However, insemination of 20 x 10(6) total sexed sperm of >or=90% purity resulted in similar numbers of transferable embryos of the desired sex compared to that for non-sexed sperm.

Animal Husbandry↗

A prospective study on the lack of development of antisperm antibodies in women undergoing intrauterine insemination.

To test the hypothesis that intrauterine insemination with washed spermatozoa induces antisperm antibody formation, we measured serum antisperm antibody levels by the Immunobead technique in a population of women receiving exogenous gonadotropins. Antibody levels were measured before therapy (baseline) and then serially during subsequent stimulation cycles, for a maximum of six cycles. Twenty-eight patients underwent intrauterine insemination; each patient served as her own control. An additional 25 patients were treated with exogenous gonadotropins but did not undergo intrauterine insemination; they served as external controls. Antisperm antibody levels in women who underwent concomitant intrauterine insemination were compared with levels in those who did not. Of the 53 enrolled patients, 18 completed six treatment cycles, and 35 achieved pregnancy before six cycles. Forty-five patients (85%) had less than 10% Immunobead binding, six (11%) had binding between 10% and 25% (mean 16%, range 14% to 20%), and two had binding greater than 25% (28% and 42%, respectively). Mean binding was similar (less than 10%) in the intrauterine insemination and external control groups. Eighteen patients conceived in the intrauterine insemination group and seventeen in the control group. Of patients who conceived, all but one had less than 10% Immunobead binding at the time of conception (mean 1.6 months). In patients who did not conceive, there was no difference in Immunobead binding between control and intrauterine insemination groups after 6 months of therapy. Our data do not support the hypothesis that serum antisperm antibody levels, as detected by Immunobead binding, will increase in menotropin-stimulated women undergoing intrauterine insemination over a prolonged treatment period.

Adult↗

Temporal relationship between insemination and sperm penetration in immature rats, with special reference to the effect of incubation of spermatozoa.

Superovulated immature rats (24 to 25 days old) were inseminated with epididymal sperm before or after ovulation and their eggs were examined at various times. When inseminated before ovulation, the interval between insemination and sperm penetration was 7 to 9 hours; the sperm penetration began approximately 2 hours after the first appearance of eggs in the oviducts and ceased 4 to 6 hours later. When inseminated after ovulation, the interval between insemination and sperm penetration was 5 to 6 hours; sperm penetration started 5 to 9 hours after ovulation and the proportion of penetrated eggs was not increased 4 hours later. The fertilizing capacity of sperm in the immature female tract lasted for 10 to 14 hours, which is shorter than in the mature animals, and sperm penetration occurred 2 to 10 hours after ovulation. The proportion of eggs fertilized, however, was not higher than 55%. A significant greater number of eggs was penetrated by more than one sperm but the number of polyspermic eggs was not increased when insemination was delayed. Epididymal sperm were incubated for various lengths of time and similarly inseminated into the uterine horns of immature rats. The fertilizing capacity of sperm could be maintained in culture for 10 hours but the proportion of fertilized eggs decreased sharply after incubation for 8 hours. Although rat epididymal sperm in a concentrated form could not be capacitated in vitro, they could be capacitated after incubation by intrauterine insemination.

Animals↗

A controlled assessment of direct intraperitoneal insemination.

OBJECTIVE: To test the efficacy of direct intraperitoneal (IP) insemination and its effect on cell-mediated immunity. DESIGN: A prospective trial with each couple having one treatment (insemination) cycle and one control (timed intercourse) cycle performed in random order with the same ovulation stimulation in both cycles. SETTING: Secondary and tertiary referral fertility clinics; university teaching hospital. PATIENTS: Twenty-six infertile couples. Excluding pregnancy, only one couple did not complete the two cycles. INTERVENTIONS: Ovulation induction in both cycles. Intraperitoneal insemination in the insemination cycles. MAIN OUTCOME MEASURES: These were pregnancy rate (treatment versus control) and mixed lymphocyte response (MLR) sensitivity (before and after direct IP insemination treatment). RESULTS: There were four control and no treatment pregnancies. This was not a significant difference (odds ratio). Mixed lymphocyte responses in fertile subjects did not change during the menstrual cycle (Wilcoxon). There was no significant increase in MLR sensitivity to partner's cells after direct IP insemination treatment. CONCLUSIONS: This controlled study found no benefit from direct IP insemination in terms of pregnancies over control cycles. There was no evidence that direct IP insemination had increased cell-mediated immune response sensitivity to husband's cells.

Adult↗

Factors associated with first service conception in artificially inseminated nulliparous Holstein heifers.

Animal and management factors associated with first service conception in nulliparous dairy heifers were determined in 601 Holstein heifers from a dairy farm in north central Florida. Animal data collected included body weight, height at the withers and tail head, body condition score at 6 months of age and just prior to first artificial insemination (AI), and pelvimetry measurements taken just prior to first AI. Management data included season of first AI, inseminator, service sire, method of estrus detection, whether the estrus of first insemination was induced using prostaglandin F(2alpha) (PGF(2alpha)), and whether the heifer received a modified live virus (MLV) vaccine within 21 days of first insemination. Data were analyzed using multivariable logistic regression. Heifers inseminated in the summer were more than four times less likely to become pregnant to first insemination than heifers bred during the rest of the year (odds ratio (OR)=0.24; 95% CI=0.14, 0.41). Using secondary signs for estrus detection instead of standing estrus resulted in significantly reduced odds of conception to first service (OR=0.37; 95% CI 0.13, 1.02). Also, heifers inseminated at estrus induced by PGF(2alpha) were approximately one-third less likely to conceive than those heifers inseminated to a naturally occurring estrus (OR=0.66; 95% CI 0.46, 0.95). An interaction between pelvic size and breeding season was found indicating that large pelvic size had a significant positive effect on fertility in the summer, but was not associated with conception to first service in the winter.

Analysis of Variance↗

Administration of oxytocin immediately after insemination does not improve pregnancy rates in mares bred by fertile or subfertile stallions.

It is probable that reduced pregnancy rates in mares bred to subfertile stallions is attributable, in part, to the reduced number of normal spermatozoa that colonize the oviduct. Administration of oxytocin stimulates both uterine and oviductal contractility. The hypothesis that oxytocin may enhance sperm transport to/into the oviducts, and thereby increase pregnancy rates, was tested in 2 trials. For both trials, fertile estrous mares with follicles > or = 35 mm in diameter were inseminated once at 24 h after administration of 1500 to 2000 U hCG. The inseminate dose was limited to 100 million spermatozoa in order to lower pregnancy rates and thus increase the chance of detecting a treatment effect. Pregnancy status was determined by transrectal ultrasound examination 14 to 16 d after insemination. In Trial 1, 49 mares were inseminated with 4 mL extended semen from 1 of 3 stallions (1 fertile and 2 subfertile males). Immediately after insemination, the mares were administered either 20 U oxytocin or 1 mL saline intravenously. In Trial 2, 51 mares were inseminated with 4 mL extended semen from 1 of 4 stallions (1 fertile and 1 subfertile male used in Trial 1, and 2 additional fertile males). Immediately after insemination, and again 30 min later, mares were administered either 5 U oxytocin or 0.25 mL saline intramuscularly. To test for effects of treatment with oxytocin and for the interaction between semen quality and treatment, a generalized linear mixed regression model was used that accounted for the split-plot design (treatment within stallions), the random effect of stallion, the fixed effect of semen quality, the binary outcome of a single breeding trial, and the varying number of trials per stallion/treatment groups. Three treatment protocols or regimens were used: placebo, 5 U oxytocin injected twice intramuscularly, and 20 units oxytocin injected twice intravenously. Semen was classified as high (fertile stallions) or low (subfertile stallions) quality. No interaction between semen quality and treatment was detected (P > 0.10). The pregnancy rate of mares treated with oxytocin immediately after insemination was 30% (15/50) compared with 50% (25/50) for mares treated with saline immediately after breeding. Administration of oxytocin did not affect pregnancy rates (P > 0.10).

Animals↗

Transmission of classical swine fever virus by artificial insemination.

Classical swine fever (CSF) virus was introduced into an artificial insemination centre during the CSF epizootic of 1997-1998 in the Netherlands. The risk of further spread of CSF virus via contaminated semen was recognised, but could not be assessed because scientific data on this issue were not available. An animal experiment was performed to determine whether CSF virus could be transmitted via artificial insemination with contaminated semen. Three boars were inoculated with a CSF virus field isolate and from Day 5 till Day 18 thereafter, ejaculates were collected and prepared for insemination. Ruttish sows were inseminated with the extended semen from Day 5 till Day 18 after inoculation of the boars. All the inoculated boars remained healthy throughout the experiment and developed CSF neutralising antibodies between 14 and 21 days after inoculation. Virus was isolated from several semen samples collected from 5 till 11 days after inoculation. Two out of six sows inseminated with CSF contaminated semen seroconverted after insemination. All the other sows remained seronegative. In the foetuses of both the seropositive sows, CSF virus was detected at approximately 35 days post insemination. These results demonstrate that adult boars infected with CSF virus can excrete virus with semen and can, subsequently, transmit the virus to sows and their foetuses via artificial insemination.

Animals↗

The use of GnRH or estradiol to facilitate fixed-time insemination in an MGA-based synchronization regimen in beef cattle.

Two experiments were conducted to compare pregnancy rates when GnRH or estradiol were given to synchronize ovarian follicular wave emergence and ovulation in an MGA-based estrus synchronization program. Crossbred beef cattle were fed melengestrol acetate (MGA, 0.5 mg per day) for 7 days (designated days 0-6, without regard to stage of the estrous cycle) and given cloprostenol (PGF; 500 microg intramuscular (im)) on day 7. In Experiment 1, lactating beef cows (n=140) and pubertal heifers (n=40) were randomly allocated to three groups to receive 100 microg gonadorelin (GnRH), 5 mg estradiol-17beta and 100 mg progesterone (E+P) in canola oil or no treatment (control) on day 0. All cattle were observed for estrus every 12 h from 36 to 96 h after PGF. Cattle in the GnRH group that were detected in estrus 36 or 48 h after PGF were inseminated 12 h later; the remainder were given 100 microg GnRH im 72 h after PGF and concurrently inseminated. Cattle in the E+P group were randomly assigned to receive either 0.5 or 1.0 mg estradiol benzoate (EB) in 2 ml canola oil im 24 h after PGF and were inseminated 30 h later. Cattle in the control group were inseminated 12 h after the first detection of estrus; if not in estrus by 72 h after PGF, they were given 100 microg GnRH im and concurrently inseminated. In the absence of significant differences, all data for heifers and for cows were combined and the 0.5 and 1.0 mg EB groups were combined into a single estradiol group. Estrus rates were 57.6, 57.4 and 60.0% for the GnRH, E+P and control groups, respectively (P=0.95). The mean (+/-S.D.) interval from PGF treatment to estrus was shorter (P<0.001) and less variable (P<0.001) in the E+P group (49.0+/-6.1 h) than in either the GnRH (64.2+/-15.9 h) or control (66.3+/-13.3 h) groups. Overall pregnancy rates were higher (P<0.005) in the GnRH (57.6%) and E+P (55.7%) groups than in the control group (30.0%) as were pregnancy rates to fixed-time AI (47.5, 55.7 and 28.3%, respectively). In Experiment 2, 122 crossbred beef heifers were given either 100 microg GnRH or 2 mg EB and 50 mg progesterone in oil on day 0 and subsequently received either 100 microg GnRH 36 h after PGF and inseminated 14 h later or 1 mg EB im 24 h after PGF and inseminated 28 h later in a 2 x 2 factorial design. Pregnancy rates were not significantly different among groups (41.9, 32.2, 33.3 and 36.7% in GnRH/GnRH, GnRH/EB, EB/GnRH and EB/EB groups, respectively). In conclusion, GnRH or estradiol given to synchronize ovarian follicular wave emergence and ovulation in an MGA-based synchronization regimen resulted in acceptable pregnancy rates to fixed-time insemination.

Animals↗

Effect of indole-3-acetic acid (plant auxin) on the preservation at 15 degrees C of boar semen for artificial insemination.

In order to extend the duration of boar sperm survival at 15 degrees C for artificial insemination, we tested the effect of indole-3-acetic acid (IAA), which appeared to be the main sperm protective substance present in the Coco nucifera endosperm (coconut water). Two IAA concentrations (10 and 100 ng/mL) in Beltsville extender (BTS) were studied for their in vitro effects. The motility, the percentage of motile spermatozoa and the acrosome morphology of sperm were recorded each day over 13 days of storage at 15 degrees C, after 5 min and 3 h of incubation at 39 degrees C. The IAA effect on sperm preservation was also studied in vivo at a concentration of 10 ng/mL in BTS by inseminating groups of females twice at 24 h intervals either at D0 (day of sperm collection) and D1 (D0/1) or at D5 and D6 (D5/6). At D0/1, the two groups of females (control and IAA) were inseminated with a total of 6.3 x 10(9) spermatozoa (3.15 x 10(9) at D0 and the same dose at D1) whereas at D5/6, on IAA group was inseminated with a total of 6.3 x 10(9) spermatozoa and another one with 12.6 x 10(9) spermatozoa. The animals in the D5/6 control group were inseminated each with a total of 12.6 x 10(9) spermatozoa. For each group of females (n = 106-140), fertility rate (% farrowing) and prolificacy rate (litter size) were recorded. No effect of IAA in vitro on the motility rate and on the percentage of motile spermatozoa was observed over a 13 day storage. However, IAA (10 ng/mL) had a significant positive effect on the percentage of living spermatozoa with intact acrosomes after 13 days (66 vs 54%, P < 0.05). The fertility and prolificacy rates after 5-6 days of sperm preservation in BTS extender alone did not differ significantly between D5/6 and D0/1 but the total number of inseminated spermatozoa was 12.6 x 10(9) at D5/6 instead of 6.3 x 10(9) at D0/1. When the spermatozoa were stored in the presence of 10 ng/mL IAA for 5-6 days at 15 degrees C, the fertility and prolificacy of the females inseminated with only 6.3 x 10(9) spermatozoa were identical to those of the females inseminated with an equal number of spermatozoa at D0/1 in the presence or absence of IAA.

Acrosome↗

Production of lambs of predetermined sex after the insemination of ewes with low numbers of frozen-thawed sorted X- or Y-chromosome-bearing spermatozoa.

The fertilizing ability of sex-sorted frozen-thawed ram spermatozoa was assessed after insemination of mature Merino ewes at a synchronized oestrus. Ewes were inseminated into the uterus or utero-tubal junction (UTJ) with a total of 140 x 10(6) unsorted (control) or 2-4 x 10(6) sorted (X or Y) frozen-thawed ram spermatozoa 54 to 57 hours after removal of progestagen-impregnated pessaries and an injection of 400 IU of pregnant mare serum gonadotrophin (Folligon, Intervet). The spermatozoa were separated into X- and Y-chromosome-bearing spermatozoa after analysis with a modified high-speed cell sorter (SX MoFlo). The number of ewes pregnant after insemination with unsorted frozen-thawed spermatozoa was significantly higher (26/48; 54.3%) than for ewes inseminated with either X- (12/48; 25.0%) or Y-sorted spermatozoa (7/48; 14.6%) (P<0.05). Seventeen of the eighteen lambs produced by ewes inseminated with X-sorted spermatozoa were female (94.4%) and 8/8 lambs from ewes inseminated with Y-sorted spermatozoa were male (100%). The sex ratio of the lambs born to ewes inseminated with sex-sorted spermatozoa was significantly skewed from the 51.3% male and 48.7% female ratio in the control group (P<0.05). This study showed, for the first time, that lambs of predicted sex can be produced after insemination with low numbers of sex-sorted cryopreserved ram spermatozoa.

Abortion, Veterinary↗

An observational study into herd-level risk indicators of return to oestrus more than five days after insemination in sow herds.

In a study population of 90 sow herds in the southern Netherlands, the occurrence of sows returning to oestrus more than five days after insemination (SRO) was investigated. In these herds information with regard to the herd system, herd size, and breeding management was recorded. The occurrence of SRO was recorded with the on-farm computer management system CBK-plus. The incidence of SRO was defined as the average number of gilts or sows returning to oestrus more than five days after insemination per 100 first inseminations. The average incidence of SRO in the study population was 18.3 per 100 first inseminations. Multivariate analysis resulted in a model with a significant effect of herd operation (herds with only sows had a lower incidence of SRO than herds with sows and finishing pigs), breeding strategy (herds with two or more inseminations per oestrus in a sow had a lower incidence of SRO than herds with one insemination per oestrus) and percentage of sows artificially inseminated (a higher percentage of artificial insemination was associated with a higher incidence of SRO).

Analysis of Variance↗