Distribution and number of spermatozoa in the oviduct of the golden hamster after natural mating and artificial insemination

A group of female hamsters was mated with males of proven fertility either several hours before or during ovulation. Another group of females was artificially inseminated several hours before ovulation. Females were killed at various times after the onset of mating or artificial insemination, oviducts were fixed and sectioned serially, and spermatozoa were counted individually as to their location in the oviduct. Regardless of the type or time of insemination, the vast majority of spermatozoa that entered the oviduct remained in the lower segments of the isthmus (the intramural and caudal isthmus) without ascending to the ampulla. The lower segments of the oviduct, particularly the caudal isthmus, appeared to be acting as a "sieve" and/or "sperm reservoir." In females mated or artificially inseminated prior to ovulation, virtually no spermatozoa reached the cephalic isthmus or ampulla until the commencement of ovulation. Although a few spermatozoa reached the ampulla by 1 h after the onset of mating, they were the exception rather than the rule. When females were mated during ovulation, spermatozoa spent a minimum of about 3 h in the caudal isthmus before ascending to the ampulla. The number of spermatozoa that entered the oviduct after artificial insemination was considerably lower than in naturally mated animals, but this low number was apparently large enough to ensure complete fertilization.     

Artificial insemination in the mouse with special reference to the effect of sperm numbers on the conception rate and litter size (author's transl)

Mature female mice (ICR-JCL), 8 to 12 weeks of age, were artificially inseminated at 8:30-9:30 a. m. on the day of estrus vaginal smear (about 3-7 hr after ovulation) with 3.18 X 10(6), 1.83 X 10(6) and 1.15 X 10(6) sperms from four, two and one cauda epididymidis, respectively, of adult males which were suspended in 50 microliter of a modified Krebs-Ringer-bicarbonate solution and incubated at 37 degrees C was under 5% CO2 in air for an hour. Immediately after insemination, pseudopregnancy induced by an artificial penis and a vaginal tampon. Out of 13 females inseminated with 3.18 X 10(6) sperms, 9 females showed placental signs and 8 of them gave birth to the mean 10.5+/-2.20 (M+/-S.D.) young at term. Four of 13 females having received 1.83 X 10(6) sperms became pregnant giving birth to the mean 4.3+/-2.1 (M+/-S.D.) young at term. On the other hand, 5 out of 6 females failed to become pregnant following insemination with 1.15 X 10(6) sperms, and only one showed a placental sign and gave birth to twelve young at term. It is concluded that the conception rate and litter size are both dependent on the number of sperms inseminated and that more than 3 X 10(6) sperms are necessary to get the conception rate and the litter size comparable to those in natural mating.     

Effect of dose of GnRH analog on ovulation in mares

Proper timing of insemination for optimal conception is accomplished by frequent palpations per rectum, by ultrasonography of the preovulatory follicle and/or by treatment with hCG or GnRH. Sustained release of GnRH from implants has been shown to hasten ovulation. Therefore, 2 studies were conducted to evaluate the efficacy of a GnRH analog, deslorelin, for hastening ovulation in nonlactating cyclic mares. The GnRH implant was 2.3 x 3.7 mm and released deslorelin for 2 to 3 days. In Experiment 1, 60 nonlactating, cycling mares were assigned to 1 of 5 doses: 0, 1.2, 1.7, 2.2 and 2.7 mg per implant. Mares were assigned sequentially on the first day of estrus (Day 1). Ovaries were examined per rectum and with ultrasonography every 12 h until ovulation. Once the mares obtained a follicle >30 mm, they were injected subcutaneously with a GnRH implant. The mares were inseminated every other day during estrus with semen from 1 of 3 stallions. Pregnancy was determined with ultrasonography. Experiment 2, 40 nonlactating, cyclic mares were assigned to 1 of 5 treatments (same treatments as in Experiment 1). Data were obtained on interval to ovulation, duration of estrus and pregnancy rates at 12, 18 and 35 d after ovulation. Time to ovulation was shorter (P<0.05) in GnRH-treated mares than in control mares in the Experiment 1. Mean time to ovulation was 68, 49, 48, 47, 44 h in Experiment 1, and 91, 66, 58, 46, 58 h in Experiment 2 for mares given 0, 1.2, 1.7, 2.2 and 2.7 mg/mare in the 2 trials. Averaged for both experiments, the proportion of mares ovulating within 48 h of treatment was 40, 75, 85, 90 and 90% for 0, 1.2, 1.7, 2.2 and 2.7 mg/mare. For both experiments, there was no effect of GnRH on pregnancy rate. In summary, a subcutaneous implant containing GnRH analog induced ovulation in most mares by 48 h of injection, and there was no advantage of doses higher than 2.2 mg/mare.     

Ovarian activity reversibility after the use of deslorelin acetate as a short-term contraceptive in domestic queens

The objective was to evaluate ovarian activity reversibility in domestic queens after short-term contraceptive treatment with deslorelin acetate. Ten mature queens were used. In all queens, the estrous cycle was evaluated every 72 h by vaginal cytology (VC) and behavior assessments. When queens had VC characteristic of interestrus or diestrus, one deslorelin acetate implant (4.7 mg) was placed in the subcutaneous tissue of the interscapular region (day of insertion = Day 0). Thereafter, VC was performed every 48 h and on Day 90, implants were removed. At Day 100, estrus and ovulation were induced with 100 IU eCG (im), followed by 100 IU hCG (im), 84 h later (Day 103.5). Queens were ovariohysterectomized on Day 106. Corpora lutea (CL) were counted, oviducts were flushed, and oocytes were identified, isolated and stained to assess viability. In all queens, blood samples for plasma progesterone concentrations were collected once a week, from Days −21 to 106. After deslorelin acetate application, four queens had VC and behavior typical of estrus, and one ovulated. Furthermore, ovulation occurred in three queens that did not have VC or behavior consistent with estrus. After the initial ovarian stimulation, all females had anestrous VC during the deslorelin treatment period. Implants were readily removed. Following implant removal, all females responded to treatments to induce estrus and ovulation. There were (mean ± SEM) 13.1 ± 5.5 CL and 8.1 ± 5.5 oocytes per queen; the oocyte recovery rate was 56.8 ± 25.4% and all recovered oocytes were viable. We concluded that deslorelin acetate can be used as a reversible short-term contraceptive in domestic cats, because estrus and ovulation were successfully induced following implant removal.     

Effects of a new injectable short-term release deslorelin in foal-heat mares

Mares treated with subcutaneous deslorelin implants on the first postpartum estrus early in the breeding season had significant reductions in the number of large follicles at early pregnancy examinations and delayed return to estrus (in mares that failed to become pregnant); these adverse effects were attributed to a prolonged release of the drug from the implant. In 2003, an injectable short-term release (<24 h) deslorelin product became available. The objective of this study was to determine if this product would hasten ovulation in early foaling first postpartum estrus mares without reducing the number of large follicles at early pregnancy examination (14-15 days postovulation). Beginning 5-6 days postpartum, first postpartum estrus (foal-heat) mares were teased daily and examined thrice weekly (Tuesday, Thursday and Saturday) by transrectal ultrasonography. Mares in estrus with a follicle > or = 34 mm diameter on Tuesdays or Thursdays were alternately assigned to: Treatment 1, n = 17; 1.5 mg injectable short-term release deslorelin, or Treatment 2, n = 16; Control (no treatment). The schedule allowed accurate determination of the number of mares ovulating within 2 days of treatment (i.e., ovulations detected on Thursday or Saturday). Mares were mated on the day of treatment and at 2-day intervals until either ovulation was confirmed or until behavioral estrus ceased. Transrectal ultrasonography was done 14-15 days after ovulation to assess ovarian follicles and pregnancy status. Fewer covers were required and more mares ovulated within 2 days of treatment in deslorelin-treated versus Control mares (P < 0.01). Pregnancy rates were normal (69%) in deslorelin-treated mares. The number of large follicles 14-15 days after ovulation did not differ between deslorelin-treated and Control mares (P > 0.10), suggesting follicular suppression did not occur with this formulation of deslorelin.     

Effect of timing of artificial insemination on gender ratio in beef cattle

It was recently reported that cows inseminated at approximately 10 or 20 h before an expected ovulation deliver predominately a bull or heifer calf, respectively. The objective of this study was to further investigate the effect of timing of insemination on the gender of offspring in cattle. Angus heifers (n = 41) and cows (n = 98) were used in the study. Heifers were synchronized with a 16-d treatment of melengestrol acetate followed 17 d later with an injection of PGF2alpha. Cows were synchronized with GnRH followed 7 d later with PGF2alpha. A HeatWatch electronic estrus detection system was used to determine the onset of estrus. Based on previous studies, it was assumed that ovulation occurs approximately 32 h after the onset of estrus. Therefore, animals were artificially inseminated at either 8 to 10 h (early; > or = 20 h before expected ovulation) or 20 to 25 h (late; < or = 10 h before expected ovulation) after the onset of estrus. Sixty to 80 d after insemination, ultrasonography was used to confirm pregnancy status and to determine the gender of fetuses. Gender of calves was subsequently confirmed at calving. Data were analyzed for effects of time of insemination and sire or semen batch on gender ratio, as well as any effect of length and/or intensity of estrus on conception rate and gender ratio. Twenty-nine of 41 heifers and 69 of 98 cows were detected in estrus after synchronization and were inseminated; 20 of 29 heifers and 48 of 69 cows were subsequently confirmed pregnant. Neither the length of estrus nor its intensity (number of mounts) had an effect on pregnancy rate or gender ratio (P > or = 0.418). Timing of insemination (early versus late) had no effect on gender ratio (P = 0.887). Semen from 13 sires representing 17 lots was used to inseminate the cows and heifers. No differences (P = 0.494) were detected in the gender ratios resulting from different sires or semen batches. In contrast to previous findings, our results indicate that inseminating beef cattle at approximately 20 or 10 h before an expected ovulation does not alter the gender ratio of the resultant calves.     

Methods of identifying and inseminating nonpregnant beef females after synchronization of second estrus with norgestomet implants

Beef females (547) were included in three experiments to evaluate methods of identifying and inseminating nonpregnant beef females after synchronization of second estrus with norgestomet implants. In the first experiment, heifers not pregnant to the first insemination were identified for insemination via estrus (inseminated via the a.m./p.m. rule or 48 h after implant removal). In the second experiment, females not pregnant to the first insemination were identified for insemination via estrus (inseminated via the a.m./p.m. rule) or progesterone concentrations < 1.5 ng/mL at implant removal (inseminated 48 h after implant removal). In the third experiment, heifers not pregnant to the first insemination were identified for insemination via progesterone concentrations (as in experiment 2) or anterior vagina electrical resistance values < 81 ohm resistance 48 h after implant removal (inseminated after resistance measured). All methods of identifying and inseminating nonpregnant females were equally effective (P > 0.10) and did not effect (P > 0.10) calving rates from the first and second AI.     

Successful artificial insemination in the koala (Phascolarctos cinereus) using extended and extended-chilled semen collected by electroejaculation

Artificial insemination in the koala using chilled, electroejaculated semen provides for a marked improvement in the reproductive and genetic management of captive koala colonies in Australia and internationally, and makes available the option of using semen collected from wild populations to expand restricted gene pools. Dilution of koala semen for artificial insemination is complicated because koalas are induced ovulators, and it is thought that ovulating factors are present in the semen, so that semen extension for preservation purposes might be anticipated to result in a failure to induce ovulation. The first two experiments of this study were designed to determine whether artificial insemination using undiluted, extended, and extended-chilled semen collected by electroejaculation was capable of inducing a luteal phase and/or the production of pouch young. In Experiment 1, 1 ml undiluted electroejaculated semen, 2 ml diluted (1:1) semen, and 1 ml diluted (1:1) semen resulted in seven of nine, six of nine, and six of nine koalas showing a luteal phase, respectively; four pouch young were produced in each treatment. A second artificial insemination experiment was conducted in which 2 ml diluted (1:1) semen was administered in three groups of nine koalas. The first group received semen that had been collected and diluted immediately without chilling, the second group was deposited with semen stored chilled for 24 h, and the final group received semen that had been chilled for 72 h. In the first group, five females had a luteal phase, but none became pregnant. In group 2, two of the five females that had a luteal phase gave birth, whereas in group 3, four of the six females that had a luteal phase produced pouch young. In addition, experiment 3 was conducted to determine whether it was possible to produce pouch young by naturally mating koalas that were in the latter stages of their behavioral estrus; this information is important to the logistics of transporting koala semen for artificial insemination by establishing the maximum time frame in which females might be expected to shed a fertile oocyte. Of the 12 females mated on Day 8 of estrus, 6 gave birth, whereas only 3 of the 10 females naturally mated on Day 10 of estrus produced pouch young. The majority of females (21 of 22) in experiment 3 showed evidence of a luteal phase. Together, these experiments have shown that it is possible to use undiluted, extended, or extended-chilled semen to produce koala offspring up to Day 8 of estrus at conception rates similar to those achieved following natural mating. These findings represent a significant advancement in the use of reproductive technology in marsupials and provide the basis for the shipment of koala semen over long distances. The pouch young produced in this study represent the first marsupials born following artificial insemination of extended-chilled semen and bring the total number of koalas produced by artificial insemination to 31.     

Artificial induction of superfetation in the European hare (<Emphasis Type="Italic">Lepus europaeus</Emphasis>)

The aim of this study was to induce superfetation in hares. On day 37 or 39 of pregnancy, female hares were treated with GnRH analogue and artificially inseminated with fresh semen. Ultrasonographic examination showed that pregnant females had follicles on the ovary on 37 days of pregnancy. After a few days from insemination performed during pregnancy, all females gave birth to healthy young, and one of the females inseminated on day 37 of pregnancy gave birth to two healthy young 42 days after insemination performed during pregnancy (39 days post first delivery). The same female in the next year gave birth to two healthy young 43 days after second insemination that was performed on the day 37 during pregnancy. The obtained results confirm that superfetation is possible to occur in hares.     

Laparoscopic intrauterine insemination in the bitch

A technique for laparoscopic intrauterine insemination in bitches is described. During natural estrus, 5 beagle bitches were inseminated and S others were naturally mated (control group) twice at a 48-h interval on Days 3 and S (n = 4) or Days 4 and 6 (n = 6) after the increase in plasma progesterone considered to be indicative of the day of the preovulatory LH peak. All the inseminations were with fresh semen and under general anesthesia. The technique involved the introductions of 1) a Verres needle to insufflate the abdominal cavity by direct punction on the middle line 1 cm over the umbilicus, 2) a laparoscope to visualize the abdominal cavity by a 1 cm puncture on the middle line 1 cm under the umbilicus, 3) a forceps used to manipulate the uterus by a 0.5 cm puncture at 2 to 3 cm lateral to the mammary glands, and 4) an 18-g catheter used to puncture the uterus on the middle line between the 3rd and 5th mammary gland. The uterine body was grasped by the forceps and elevated against the ventral abdominal wall. The 18-g catheter was then inserted through the abdominal wall directly into the uterine lumen, and 1.0 ml of fresh semen containing 250 to 480 x 10(6) spermatozoa/ml was injected. The inseminations resulted in pregnancies in all animals. Litter size was similar in the artificially inseminated and naturally mated bitches (5 +/- 1.8 and 4.8 +/- 1.6 pups per litter, respectively). Bitches in the artificially inseminated group delivered at 65.2 +/- 0.8 d and in the natural mated group at 65.4 +/- 0.5 d after the LH peak. In conclusion, this paper gives the first results of intrauterine laparoscopic insemination in bitches, indicating interesting perspectives for this technique in dog's reproduction.     

Effect of a deslorelin implant in a timed artificial insemination protocol on follicle development, luteal function and reproductive performance of lactating dairy cows

This study examined the influence of a GnRH agonist containing either 450 or 750 microg of deslorelin in an implant form or a gonadorelin injection (control) to induce ovulation in the Ovsynch protocol on pregnancy rates (PR), embryonic loss, and ovarian function in 593 lactating Holstein cows. Cows were given two injections of PGF2alpha 14 days apart, followed 14 days later by the Ovsynch protocol, and were timed artificially inseminated (TAI) at 68 +/- 3 days postpartum. Blood samples for determination of plasma progesterone concentrations were collected at 24 and 10 days prior to and 11 days after TAI. Pregnancy was diagnosed on Day 27 and reconfirmed on Day 41 after TAI. Non-pregnant, not re-inseminated cows at Day 27 had their ovaries examined by ultrasonography, and the number and size of follicles and presence of luteal tissue were determined. Simultaneously, these cows were re-synchronized with the Ovsynch protocol. Pregnancy during the re-synchronization period was determined between 35 and 41 days after insemination. On Day 27, PR were higher for control (39.0%) and deslorelin 450 microg (DESLORELIN 450) implant (41.3%) than for those receiving the deslorelin 750 microg (DESLORELIN 750) implant (27.5%; P<0.05). Pregnancy losses tended to decrease for DESLORELIN 450 compared with control (5.0% versus 12.7%; P<0.13). Plasma progesterone concentrations did not differ significantly among treatments. Deslorelin suppressed ovarian activity and decreased PR during the re-synchronization period compared with control. The percentage of non-pregnant animals that were re-inseminated by Day 27 was less for deslorelin compared with control. In conclusion, incorporation of an implant of the GnRH agonist deslorelin to induce ovulation in the Ovsynch protocol has the potential to reduce pregnancy losses, but the response was dependent upon implant concentration. Evaluation of lower doses to minimize the negative effects on subsequent fertility is warranted.     

Effect of time of ovulation and sperm concentration on fertilization rate in gilts

In normal production practices, sows and gilts are inseminated at least twice during estrus because the timing of ovulation is variable relative to the onset of estrus. The objective of this study was to determine if a normal fertilization rate could be achieved with a single insemination of low sperm number given at a precise interval relative to ovulation. Gilts (n=59) were randomly assigned to one of three treatment groups: low dose (LD; one insemination, 0.5 x 10(9) spermatozoa), high dose (HD; one insemination, 3 x 10(9) spermatozoa) or multiple dose (MD; two inseminations, 3 x 10(9) spermatozoa per insemination). Twice daily estrus detection (06:00 and 18:00 h) was performed using fenceline boar contact and backpressure testing. Transrectal ultrasonography was performed every 6 h beginning at the detection of the onset of standing estrus and continuing until ovulation. Gilts in the LD and HD groups were inseminated 22 h after detection of estrus; MD gilts received inseminations at 10 and 22 h after detection of estrus. Inseminations were administered by using an insemination catheter and semen was deposited into the cervix. The uterus was flushed on Day 5 after the onset of estrus and the number of corpora lutea, oocytes, and embryos were counted. Time of insemination relative to ovulation was designated as 40 to >24 h, 24 to >12 h, and 12 to 0 h before ovulation and >0 h after ovulation. The LD gilts had fewer embryos (P<0.04), more unfertilized oocytes (P<0.05) and a lower fertilization rate (P<0.07) compared to MD gilts. The effects of time of insemination relative to ovulation and the treatment by time interaction were not significant. We conclude that a cervical insemination with low spermatozoa concentration may not result in acceptable fertility even when precisely timed relative to ovulation.     

Intraperitoneal insemination of the guinea pig with synchronized estrus induced by progesterone implant.

Female guinea pigs with synchronized ovulation by means of implantation of progesterone-filled tubing (P-tube) followed by a progesterone injection, were inseminated by intraperitoneal injection with sperm suspension. First, to obtain the optimum conditions for insemination, the females were inseminated singly over the range of 1-10 x 10(7) spermatozoa before and after the synchronized ovulation. The incidence of conception and implantation was 100% in the females given more than 5 x 10(7)/animal at 9:00 h on the 5th day after removal of the P-tube. Second, the reproductive ability of the inseminated females under this optimal condition was observed throughout the pregnancy to delivery. Inseminated females had a mean +/- S.D. gestation period of 68.7 +/- 0.5 days, a litter size of 2.8 +/- 0.6 pups and body weight of 110 +/- 14 g. These data were comparable to those of naturally-mated females. Our findings suggest that the artificial insemination by intraperitoneal injection in combination with the synchronized estrus technique is very useful for production control in a small colony of guinea pigs.     

Synchronization of estrus and ovulation and associated endocrine changes in Bos indicus cows

The effects of 4 estrus synchronization treatments on intervals to and synchrony of estrus and ovulation, on timing of the preovulatory LH surge and associated changes in plasma progesterone, LH, FSH, and 17beta-estradiol (E(2)) were investigated in 48 Bos indicus cows. Treatment 1 consisted of 2 injections of PGF(2alpha) 14 d apart (n = 12); Treatment 2 of a subcutaneous 3-mg norgestomet implant and an intramuscular injection of 3 mg of norgestomet and 5 mg estradiol valerate, with the implant removed 10 d later (n = 12; norgestomet-estradiol); Treatment 3 of norgestomet-estradiol, with a subcutaneous injection of PMSG given at time of implant removal (Day 10; n = 12); and Treatment 4 of norgestomet implant (as for Treatments 2 and 3) inserted for 10 d, with an intramuscular injection of PGF(2alpha) given at the time of implant removal (n = 12). The experiment was conducted in 2 replicates (24 cows/replicate, 6 cows/group). Estrus, ovulation and timing of the preovulatory surge of LH varied less in cows treated with norgestomet-estradiol and PMSG than in cows in Treatments 1 and 4 (P < 0.008). Treatment with PMSG reduced variation in ovulation times and timing of the LH surge in cows treated with norgestomet-estradiol (P < 0.02). Concentrations of E(2) were higher in cows in Treatments 2 and 3 on the final day of treatment and at about 6 h post ovulation compared with cows in Treatments 1 and 4 (P < 0.05). Different methods for synchronizing estrus did not alter sequential endocrine and behavioral changes in relation to the timing of the LH peak, and the results were consistent with current recommendations for insemination times in Bos taurus cattle.     

Effect of insemination timing on the fertilizing capacity of frozen/thawed equine spermatozoa

A breeding trial was conducted to evaluate the effect of insemination timing on the fertility of mares bred with frozen/thawed equine semen. One stallion and 60 reproductively sound, estrous-synchronized mares were included in the study. Mares were assigned to one of three groups (n = 20): 1) insemination with fresh semen every other day during estrus from detection of a 35-mm follicle until ovulation, 2) insemination with frozen/thawed semen every day during estrus from detection of a 35-mm follicle until ovulation or 3) insemination with frozen/thawed semen once, within 6 h after ovulation. Single-cycle 18-d pregnancy rates resulting from insemination with fresh semen (70%), preovulation insemination with frozen/thawed semen (60%) and postovulation insemination with frozen/thawed semen (55%) were not different (P > 0.05). Possibly, equivalent pregnancy rates could be achieved with frozen/thawed semen using either daily inseminations until ovulation occurs or frequent ovarian palpations with a single post-ovulation insemination. Further studies regarding the effect of insemination timing on stallion fertility are needed since the present investigation included only one stallion and a small number of mares.     

Investigations on the detrimental effect of prostaglandin F2α-regulated estrus on the number and condition of sperm in the reproductive tract of the ewe

Ewes in the luteal phase of the estrous cycle were treated with prostaglandin F₂α (PGF), mated to rams at the ensuing estrus 2 days later, and necropsied at 2 or 23 hr after mating. At 2 hr after mating, ewes in PGF-regulated estrus had significantly fewer sperm in the middle and anterior one-thirds of the cervix and in the uterus than did ewes mated during natural estrus. At 23 hr, soon after ovulation, significantly fewer ewes in PGF-regulated estrus had sperm in the oviducts than did ewes in natural estrus.In Experiment 2, ewes in PGF-regulated or natural estrus were laparotomized, inseminated by deposition of semen in the uterine lumen, and necropsied 2 or 23 hr later. Intrauterine insemination prevented most of the reduction in sperm numbers in the reproductive tract at PGF-regulated estrus.In Experiment 3, ewes in PGF-regulated or natural estrus were either mated to rams or inseminated in the uterine lumen and necropsied 2 hr later. Sperm were recovered from three segments of the cervix and were counted and evaluated for motility, response to live-dead staining, and acrosomal morphology. Intrauterine insemination again reduced the detrimental effect of PGF-regulated estrus on sperm numbers. However, the percentages of sperm recovered from the cervix that were motile, live, and had normal acrosomes were much lower in ewes in PGF-regulated estrus than in ewes in natural estrus. Compared with natural mating, intrauterine insemination reduced but did not eliminate the detrimental effects of PGF-regulated estrus on the viability and morphology of sperm. Regulating estrus with PGF resulted in damage to sperm in the cervix regardless of whether sperm reached the cervix from the vagina or from the uterus.     

Estrus, ovulation and conception following timed insemination in Romney ewes treated with progestagen and gonadotropins.

The estrus — ovulation time relationships was examined in Romney ewes treated with progestogen (intravaginal sponge) and gonadotropins (PMSG + HCG or PMSG alone) prior to (January) and during (April) the breeding season. The conception rate of ewes inseminated at predetermined times after treatment was also investigated.Ewes exhibited estrus sooner after sponge removal in April than in January (34.9 v 38.9 hrs, P < 0.001). The interval from sponge removal to ovulation was also shorter in April than in January (56.3 – 62.1 hrs, P < 0.01). There were no significant differences between treatments or season on the mean interval from estrus to ovulation. Types of gonadotropin treatment had no effect on the estrus — ovulation time relationships. There were no significant effects of season, hormone treatment or time of insemination on lambing rate.     

Artificial insemination of subtropical commercial beef cattle following synchronization with cloprostenol (ICI 80996): II. Estrous response

Data collected from two controlled breeding field trials involving 561 Bos indicus x Bos taurus cows and heifers were analyzed for estrous and fertility response following a cloprostenol ICI-80, 996 (CLP) synchronization regime. Fertility data were discussed in a companion paper (1). In Trial 1, 128 animals were assigned to four treatments: 1) controls which were inseminated at the naturally occurring estrus; 2) Animals artificially inseminated at approximately 72 hr and 96 hr following a second CLP; 3) Animals artificially inseminated at approximately 72 hr following a second CLP; and 4) Animals artificially inseminated approximately 12 hr after detection of estrus post-second CLP. Trial II included 391 heifers distributed among six treatments: 1) Artificially inseminated between 70 and 90 hr post-second CLP; 2) Sham inseminated between 70 and 90 hr post-second CLP; 3) Processed with no manipulation of the genital tract between 70 and 90 hr post-second CLP; 4) Artificially inseminated approximately 12 hr after the detection of estrus following a second CLP; 5) Artificially inseminated at the naturally occurring estrus and 6) Non-treated heifers exposed to fertile bulls. Cloprostenol ICI-80996 was effective (P < .01) in synchronizing estrus in comparisons of treated vs non-treated controls in Trials I and II (82 vs 29%; 57 vs 19%, respectively). However, a significant reduction in the expression of estrus was observed following Timed AI when compared to heifers bred 12 hr after detection of CLP-induced estrus in Trial II (37 vs 54%, P < .05). The authors conclude that a single timed insemination of Brahman crossbred heifers suppresses the behavioral expression of estrus. Other evidence (1) indicates that the fertility during this period is similarly reduced.     

Induction of ovarian activity and ovulation in an induced ovulator,the maned wolf (Chrysocyon brachyurus), using GnRH agonist and recombinant LH

Assisted reproductive techniques, such as ovarian manipulation and artificial insemination, are useful for enhancing genetic management of threatened wildlife maintained ex situ. In this study, we used noninvasive fecal hormone monitoring to investigate (1) the influence of pairing with a male on endocrine responses of female maned wolves (Chrysocyon brachyurus) to a GnRH agonist (deslorelin) and (2) the efficiency of recombinant LH (reLH) on ovulation induction in females housed alone. Deslorelin (2.1 mg Ovuplant) was given to females that were either paired with a male (n = 4) or housed alone (n = 7); the implant was removed 7 to 11 days postimplantation. Three of seven singleton females were injected with reLH (0.0375 mg) on the day of implant removal, whereas the remaining females (n = 4) did not receive the additional treatment. Fecal samples were collected 5 to 7 days/wk from all females starting 11 days prior to hormone insertion until at least 70 days post implant removal for a total of 11 hormone treatment cycles. Fecal estrogen and progestagen metabolites were extracted and analyzed by enzyme immunoassay. Evidence of ovulation, demonstrated by a surge of estrogen followed by a significant rise in progestagen, occurred in all paired females. Three of the four singleton females that did not receive reLH treatment exhibited no rise in progestagen after an estrogen surge. All singleton females treated with reLH exhibited a rise in fecal progestagen after injection, indicating ovulation. In conclusion, deslorelin is effective at inducing ovarian activity and ovulation in paired female maned wolves; however, exogenous reLH is needed to induce ovulation in females housed alone. The findings obtained from this study serve as a foundation for future application of artificial insemination to enhance genetic management of this threatened species ex situ.     

Estimation of intracolonial worker relationship in a honey bee colony (Apis mellifera L.) using DNA fingerprinting

Summary The number and frequencies of subfamilies in a honey bee colony were determined by DNA fingerprinting. Queen and brood samples were taken from three colonies with artificially inseminated queens and from one colony with a naturally mated queen. UsingHae III restriction enzyme and (GATA)₄ oligonucleotide, the number of subfamilies in the colonies with artificially inseminated queens corresponded with the number of drones used for insemination. In the colony with the naturally mated queen, 12 subfamilies were found in a random sample of 104 workers. Considering that subfamily frequencies range from 1 to 26%, introcolonial worker relationship was estimated to be 0.328, corresponding to a genetical effective number of 6.4 matings.