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PubMed2001

The effect of estradiol benzoate on synchrony of estrus and fertility in cattle after removal of a progesterone-releasing intravaginal device.

The aim was to determine the effect of estradiol benzoate (EDB) given after removal of a progesterone-releasing intravaginal device (PRID) at either emergence or dominance of a follicle wave, on the interval to estrus, variation in its onset and pregnancy rate in heifers. Heifers (n=186) were assigned randomly to four treatments in a 2 x 2 factorial design; emergence or dominance of a follicle wave at PRID removal, with or without 0.5 mg EDB 24 h after PRID removal. Ovarian ultrasonography was performed to confirm follicular status; data from heifers of undeterminable follicular status were excluded (n=36). Mean size of the largest follicle of the new wave at PRID removal was smaller (P < 0.01) in heifers given EDB at emergence (6.3 +/- 0.09 mm) compared with those given it at dominance (10.9 +/- 0.30 mm). The onset of estrus was earlier (P < 0.01) in heifers given EDB at dominance (median 42 h, range 13 h) compared with those not given EDB at dominance (median 43 h, range 42 h). The median interval to estrus was decreased (P < 0.01) in heifers given EDB at emergence (median 48 h, range 73 h) compared with those not given EDB at emergence (median 66 h, range 45 h). Variation in onset of estrus was reduced (P < 0.05) in heifers given EDB compared with those not given EDB. The pregnancy rate was not affected when EDB was given at dominance, however, it was decreased (P < 0.05) when given at emergence (23 of 40 vs 26 of 32, respectively). To determine the effect of EDB on follicular dynamics in heifers treated with EDB at emergence, heifers (n=37) were assigned to two treatments: at emergence with or without EDB and their ovaries were examined daily using ultrasonography. Follicular dynamics were not different (P > 0.05) in EDB-heifers compared with untreated controls. Mean serum estradiol was greater (P < 0.01) in EDB-treated heifers compared with controls. In conclusion, 0.5 mg EDB given 24 h after PRID removal to heifers decreased the interval to estrous onset at emergence or dominance, decreased variation in onset of estrus and decreased pregnancy rates when given at emergence of a follicle wave.

Animals↗
PubMed2001

Factors affecting frozen and fresh embryo transfer pregnancy rates in cattle.

The effects of a large number of factors on the pregnancy rates of fresh and frozen cattle embryos were examined over a period of years at several different locations. For fresh embryos, overall pregnancy rates were 68.3% (n=9023) and 77.1% (n=2650) at different locations and time periods. Frozen-thawed embryo pregnancy rates were 56.1% (n=3616) in The Netherlands and 58.4% (n=5297) and 68.7% (n=774) for two studies in the United States. Pregnancy rates of surgical versus nonsurgical transfers were very similar. There were no differences in the pregnancy rates of beef versus dairy embryos, but the pregnancy rate was higher in dairy and beef heifers and beef cows than in dairy cows. Although on-farm pregnancy rates in California were higher than in the northeast United States, there was no influence of season on pregnancy rate. Estrous asynchrony between plus and minus 24 h did not affect pregnancy rate for frozen-thawed or fresh embryos. Neither breed nor parity of recipients affected the influence of asynchrony on pregnancy rates. Embryo grade was a significant factor in pregnancy rate for both fresh and frozen-thawed embryos, but neither embryo stage nor age was a significant factor. Pregnancy rate was not affected by holding embryos after flushing for up to 3 h prior to freezing.

Age Factors↗
PubMed2002

Early embryonic cells from in vivo-produced goat embryos transmit the caprine arthritis-encephalitis virus (CAEV).

The aim of this study was to investigate whether cells of early goat embryos isolated from in vivo-fertilized goats interact with the caprine arthritis-encephalitis virus (CAEV) in vitro and whether the embryonic zona pellucida (ZP) protects early embryo cells from CAEV infection. ZP-free and ZP-intact 8-16 cell embryos were inoculated for 2 h with CAEVat the 10(4) tissue culture infectious dose 50 (TCID50)/ml. Infected embryos were incubated for 72 h over feeder monolayer containing caprine oviduct epithelial cells (COECs) and CAEV indicator goat synovial membrane (GSM) cells. Noninoculated ZP-free and ZP-intact embryos were submitted to similar treatments and used as controls. Six days postinoculation, infectious virus assay of the wash fluids of inoculated early goat embryos showed typical CAEV-induced cytopathic effects (CPE) on indicator GSM monolayers, with fluids of the first two washes only. The mixed cell monolayer (COEC + GSM) used as feeder cells for CAEV inoculated ZP-free embryos showed CPE. In contrast, none of the feeder monolayers, used for culture of CAEV inoculated ZP-intact embryos or the noninoculated controls, developed any CPE. CAEV exposure apparently did not interfere with development of ZP-free embryos in vitro during the 72 h study period when compared with untreated controls (34.6 and 36% blastocysts, respectively, P > 0.05). From these results one can conclude that the transmission of infectious molecularly cloned CAEV-pBSCA (plasmid binding site CAEV) by embryonic cells from in vivo-produced embryos at the 8-16 cell stages is possible with ZP-free embryos. The absence of interactions between ZP-intact embryos and CAEV in vitro suggests that the ZP is an efficient protective embryo barrier.

Animals↗
PubMed2003

Insemination time and dilution rate of cooled and chilled ram semen affects fertility.

Adult Merino ewes (n=448) were apportioned into two groups and inseminated with: extended at 30 degrees C with skim milk and stored for 6h at 15 degrees C (cooled semen) or extended with skim milk-citrate trisodium with egg yolk and stored for 24h at 5 degrees C (chilled semen). Each group was further subdivided according to the time of cervical insemination at 42, 46 and 50h after pessary (MAP-60 mg) removal and according to the dilution of the semen (120 x 10(6) spermatozoa in 0.05, 0.1 and 0.2 ml). The pregnancy rate after insemination with cooled semen was 50% better than that after chilled semen (56.7 vs. 37.5%; P<0.001). Pregnancy rate was not affected by the volume of insemination; however, there was a tendency of increased lambing rate with an insemination dose of 0.1 cc (1:2, dilution), especially when the ewes were inseminated with cooled semen. The effect of time on insemination was significant only in ewes inseminated with chilled semen at 5 degrees C (P<0.01). Insemination carried out 46 h after pessary removal resulted in higher pregnancy and lambing rate (36.5, 31.1; 52.0, 45.3; and 24.0, 20.0 at 42, 46 and 50h, respectively). Pregnancy of ewes inseminated with chilled semen at 46 h after pessary removal was similar to that obtained using cooled semen (52.0 vs. 56.7%). From this study, it is concluded that advancing the time of insemination with chilled semen at 5 degrees C improves pregnancy and that the lambing obtained under these conditions is similar to the one obtained with cooled semen.

Animals↗
PubMed2002

Effect of follicular status on superovulatory response in ewes is influenced by presence of corpus luteum at first FSH dose.

The present study was developed to assess possible effects on ovulatory response and embryo yields arising from the presence of a corpus luteum (CL) at the time of initiation of the progestagen treatment used in superovulatory protocols in sheep. In breeding season, estrus was synchronized in 25 Manchega ewes using 40 mg FGA sponges for 14 days, together with a single dose of 125 microg of cloprostenol on Day 12, with Day 0 as day of progestagen insertion. Superovulatory treatment consisted of eight decreasing doses (1.5 x 3 ml, 1.25 x 2 ml, and 1 x 3 ml) of Ovagen twice daily from 60 h before to 24 h after sponge removal. The presence or absence of corpora lutea was assessed by transrectal ultrasonography at progestagen insertion and at first FSH dose. Number and size of all follicles > or = 2 mm were also evaluated at first FSH dose. The number of corpora lutea and the number and viability of recovered embryos in response to the treatment were evaluated 7 days after sponge removal. No significant effect on ovarian response of the presence of a CL at sponge insertion in 21 of the 25 ewes (84%) was detected. However, ewes with a CL at first FSH dose (16 ewes, 64%) yielded a higher number of transferable embryos (7.2 +/- 1.4 versus 2.7 +/- 0.7, P < 0.05), since the embryo degeneration rate was increased in sheep without a CL (42.5% versus 12.7%, P < 0.01). Analysis of possible effects derived from the presence of a large presumptively dominant follicle (> or = 6 mm) at first FSH dose showed that both recovery and viability rates were lowest (P < 0.05) in ewes bearing a large follicle in the absence of a CL (40.5 and 50.6%, respectively), and highest in ewes that did not show a large follicle but in which a CL was present (73.9 and 85.2%). The final number of transferable embryos was very different between groups (10.2 versus 1.8, P < 0.01). These results indicate that the number and quality of embryos obtained from superovulated ewes is affected by the presence of a CL prior to the first FSH dose (i.e. by the stage of the estrous cycle at progestagen insertion) and also by an interaction with suppressive effects from large dominant follicles. This finding suggests the existence of some effects on follicular population prior to the FSH treatment that may compromise follicle and oocyte developmental competence. It seems reasonable to hypothesize that superovulatory yields would be increased by beginning the treatment during the early-luteal phase of the estrous cycle, allowing for the presence of a CL along with the progestagen treatment.

Animals↗
PubMed2003

Screening of some variables influencing the results of embryo transfer in the ewe. Part II: two-day-old embryos.

Each of sixty Rasa aragonesa ewes received two embryos on Days 2-3 of the estrous cycle (Day 0=estrus) from 27 donors of the same breed that were superovulated with pFSH. The influence of several variables on fertility and prolificacy after transfer was studied by discriminant analysis. Our results showed that the main variables contributing to higher fertility were: in the donor-recipient couple, degree of estrus synchrony between them (better if donors were in estrus before recipients); in recipients, interval from FGA withdrawal to estrus onset, prolificacy in the previous lambing, age (all, better if inferior to the mean) and interval from the previous lambing (better if superior to the mean); in donors, ovulation rate (better if lower than the mean); and in embryos, developmental stage (better if superior to the mean). Likewise, the main variables contributing to higher prolificacy were: in donors, body condition score (better if higher than the mean) and weight (better if inferior to the mean); and in recipients, plasma progesterone concentration at transfer (better if inferior to the mean). The percentage of ewes correctly classified as lambing or not was 71.7% (P<0.01), and 72.5% of the ewes were correctly classified as having one or two lambs (P<0.05). Whether the criteria we have found for optimum results after transfer are applicable or not to conditions other than ours will need to be confirmed.

Age Factors↗
PubMed2003

Early pregnancy diagnosis in sheep by progesterone and pregnancy-associated glycoprotein tests.

The aim of this study was to compare the accuracy of the progesterone (P4) and pregnancy associated glycoprotein (PAG) tests for determination of early pregnancy in sheep. Estrus was synchronized in 182 Awassi x Merino ewes and blood samples were collected at Days 0 (day of the insemination), 18, 22, 29, 36, and 50 after artificial insemination (AI). Plasma P4 concentrations at Days 0 and 18 were determined by double antibody radioimmunoassay, while PAG concentrations at Days 22, 29, 36 and 50 were determined by a heterologous, double-antibody radioimmunoassay (RIA) using the bovine PAG 67 kDa subunit as tracer and standard and rabbit antiserum raised against a mixture of caprine 55 and 59 kDa PAG subunits as the first antibody. The discriminatory value for diagnosis of pregnancy by the P4 and the PAG-RIA tests was > or = 1 ng/ml. Based on lambing data, the accuracy for diagnosing pregnant (sensitivity) and non-pregnant ewes (specificity) and predictivity of both tests were calculated. The sensitivity, specificity, positive and negative predictive values for P4 and PAG tests were 100, 95.4, 81.6, and 100% at Day 18 (P4) and 93.5, 100, 100 and 98.7% at Day 22 (PAG), respectively. For diagnosis of non-pregnant ewes the PAG test had significantly higher specificity than the P4 test (P < 0.05). It is concluded that ovine pregnancy can be reliably diagnosed at Day 22 after AI by using a heterologous radioimmunoassay of PAG.

Animals↗
PubMed2003

Is fertility declining in dairy cattle? A retrospective study in northeastern Spain.

The past few decades have seen a dramatic increase in infertility and reproductive disorders associated with a rising milk yield. Herein, we present a 10-year (from 1991 to 2000) retrospective survey of these factors using data from a reproductive management program performed on high-yielding dairy herds in north-east Spain. The data series included 12,711 lactations. The year was divided into warm and cool periods. Data were obtained from cows first inseminated or examined 45-70 days postpartum. The reproductive tract of each animal was examined by palpation per rectum within 43-48 days postpartum. Cows were then weekly examined until insemination or until postpartum Day 70. Cows with a corpus luteum were synchronized for estrus and timed AI. Cows showing natural estrus in the same period were also inseminated. All inseminations were pooled as a single group and inseminated cows were considered cyclic. Inactive ovaries and ovarian cysts were recorded as ovarian disorders. Incomplete uterine involution, endometritis and pyometra were grouped as uterine disorders. Overall cyclicity and pregnancy rates of all AI cows, and cyclicity and pregnancy rates corresponding to the warm period significantly decreased over the 10-year period, yet remained practically constant during the cool period. The incidence of inactive ovaries in the entire population and that corresponding only to cows examined during the warm period significantly increased with time but was similar during the cool period. Ovarian cysts were more frequent during the warm (12.3%) than during the cool (2.4%) period, though these proportions were maintained throughout the study. The incidence of uterine disorders significantly decreased with time and did not differ between cool and warm periods. Milk yield per cow and year increased from 7800 kg in 1991 to 10,200 kg in 2000. Regression analysis revealed that, for all cows and those inseminated or examined in the warm period respectively, each 1000 kg increase in average milk yield was related to decreases of 3.2 and 6% in pregnancy rate, 4.4 and 7.6% in cyclicity, and to increase of 4.6 and 8% in the incidence of inactive ovaries. The rate of uterine disorders decreased 1.1% regardless of season. Our overall results clearly reflect the increased infertility and incidence of reproductive disorders over the study period. This occurred simultaneous to increasing average milk yield. Nevertheless, under our study conditions, a cool environment appears to preserve fertility and reduce the risk of reproductive disorders irrespective of the milk yield. These findings prompt the need to improve management practices by attempting to reduce the effects of factors provoking stress.

Animals↗
PubMed2003

Effects of presynchronization during the preservice period on subsequent ovarian activity in lactating dairy cows.

Among the strategies aimed at overcoming difficulties in estrus detection in dairy herds, presynchronization with two PGF2alpha treatments 14 days apart before a timed AI protocol has been related to a significant increase in pregnancy rates. The aim of the present study was to evaluate the effects of presynchronization during the preservice period on subsequent ovarian activity in clinically normal lactating dairy cows. A second objective was to evaluate the incidence of reproductive disorders on Day 50 postpartum. Depending on the chronological order of parturition, cows were alternately assigned to a control (n=102) or treatment (n=101) group. Animals in the treatment group were administered two cloprostenol treatments 14 days apart, beginning on Day 22 postpartum. The reproductive tract of each animal was examined ultrasonographically on Days 43 and 50 postpartum to monitor ovarian structures and uterine contents. Blood samples were collected on Day 50 for progesterone determination. Cows were inspected for signs of estrus between Days 50 and 71 postpartum and were then inseminated. Follicular persistence rates were similar in the presynchronized (14.9%) and control (13.7%) groups. Cows in the presynchronized group showed a lower metritis-pyometra rate (0% < 3.9%; P=0.045); a lower ovarian cyst rate (3% < 10.8%; P=0.03); a higher luteal activity rate (progesterone concentrations>/=1ng/ml) on Day 50 postpartum (76.2% > 52.9%; P=0.0005); a higher estrus detection rate (73.3% > 47.1%; P<0.0001); a higher ovulation rate (72% > 44%; P<0.0001) and a higher pregnancy rate (29.7% > 15.7%; P=0.02) than controls. Our results indicate that presynchronization during the preservice period reduces the incidence of ovarian cysts and metritis-pyometra determined on Day 50, and improves ovarian activity from Days 50 to 71 postpartum along with pregnancy rates in clinically normal lactating dairy cows.

Animals↗
PubMed2003

Absorbable deslorelin implants (Ovuplant) prolong postpartum anestrus in early ovulating dairy cows.

Two experiments were conducted to investigate the use of a bioabsorbable implant of the GnRH agonist deslorelin to temporarily delay the resumption of postpartum ovulatory cycles in Holstein cows. In Experiment 1, recently calved cows were paired and received either a single implant (Ovuplant); Peptech Animal Health, Sydney, NSW, Australia) within 48 h of parturition (OVP; n=17), or remained as untreated controls (CON; n=17). Blood samples were collected for plasma progesterone assay three times weekly for 6 weeks to profile the pattern of resumption of ovulatory cycles. In Experiment 2, there were 15 CON and 15 OVP cows initially treated as for Experiment 1 as well as 15 OVP+SYNCH cows. Each cow in the CON and OVP+SYNCH groups received a progesterone vaginal insert (CIDR); Genetics Australia, Bacchus Marsh, Vic., Australia) for 7 days at 23 days postpartum (23 dpp) to synchronise estrus in cycling animals or to induce an ovulation with estrus in anestrus animals. Blood samples were collected weekly until removal of the CIDR insert, and then twice weekly until 56 dpp to monitor plasma P4 for retrospective determination of ovulation. Milk yield was monitored by twice daily electronic volume measurements and milk composition with once weekly milk composition analysis. In Experiment 1, CON cows began ovulating from 9 dpp; 15 of 17 had ovulated by the end of blood sampling at 42 dpp. None of the OVP cows ovulated until at least 24 dpp, and only 6 of 17 had ovulated by 42 dpp. The average day of first ovulation was extended from 22.4+/-2.7 dpp to 39.3+/-2.7 dpp (P<0.05). In Experiment 2, ovulation had occurred in 8 of 15 CON cows at the time of CIDR insertion (23 dpp), 0 of 15 OVP cows and 1 of 15 OVP+SYNCH cows. By 40 dpp (or 10 days following removal of the CIDR insert) every CON cow (15/15) had ovulated, but only 2 of 15 OVP+SYNCH cows and 1 of 15 OVP cows. None of these effects of treatment was associated with any changes in milk yield or composition in either experiment. In conclusion, inserting a bioabsorbable implant of deslorelin within 48 postpartum extended the interval to first ovulation to at least 24 dpp in 46 of 47 cows. Recovery periods were highly variable. This variability was not reduced by using a form of intravaginal progesterone supplementation that did produce a synchronised estrus with ovulation in anestrus animals that had not been treated with deslorelin.

Absorption↗
PubMed2003

Efficacy of two types of vaginal sponges to control onset of oestrus, time of preovulatory LH peak and kidding rate in goats inseminated with variable numbers of spermatozoa.

In small ruminants, progestagen-impregnated vaginal devices (sponges) are useful tools to manage reproduction irrespective of season and to the application of timed artificial insemination (AI). A novel progestagen releasing vaginal-controlled release device (Chronogest CR), loaded with less (20mg) cronolone using proprietary procedures, was developed and its efficacy (synchronising ability, fertility and prolificacy following sponge removal) evaluated versus the existing Chronogest sponge containing 45 mg of cronolone in goats. Females (n=199) were maintained in field conditions and inseminated with graded amounts of spermatozoa at two stages of the year (breeding and non-breeding seasons). The use of the new Chronogest CR sponge was associated with an earlier initiation of the LH surge (28.7h versus 30.8h following sponge removal, P<0.01). A similar degree of synchronisation of the LH surge was obtained with both types of sponges. In both treatment groups, a longer time interval between sponge removal and the LH surge was noted in females with high milk production. Fertility and prolificacy were high and unaffected by the type of sponge used or the amount of spermatozoa inseminated. It is concluded that the new Chronogest CR sponge allows a reduction of the progestagen load from 45 to 20mg without detrimental effects on synchronisation, fertility and prolificacy.

Animals↗
PubMed2004

Resynchrony of postpartum dairy cows previously treated for anestrus.

Cows that are diagnosed as anestrus (defined as >3 weeks postpartum, not detected in estrus by 1 week before commencement of seasonal breeding and without a palpable corpus luteum) have a lower probability of being inseminated, a lower conception rate to insemination and hence a lower probability of pregnancy within the breeding period. A current progesterone (P) and estradiol benzoate (EB) treatment for anestrus results in an 85% insemination rate, but only 57% of cows not conceiving to that first insemination are subsequently detected in estrus 14-28 days later. Resynchrony after an initial anestrous treatment has been used to increase the probability that cows not conceiving to first insemination will subsequently be detected in estrus. Anestrous cows (n=971) were initially treated with an intravaginal P-releasing device for 6 days and given 1 mg EB 1 day after device removal (day of EB treatment=Day 0). Cows detected in estrus between Days 0 and 3 were assigned randomly to be treated with reinsertion of a used P-releasing device for 8 days (commencing on Day 15), with 0.5 mg EB at reinsertion and again 1 day after removal (EB-RS), treatment as for EB-RS group but with substitution of 250 microg GnRH for EB at device reinsertion (GnRH-RS), or left as untreated controls (no-RS). Resynchrony treatments increased the proportion of non-pregnant cows detected in estrus from Days 14 to 28 compared to no-RS (79.1, 69.8, and 55.1% for EB-RS, GnRH-RS, and no-RS, respectively; P<0.05). Fewer cows were pregnant by Days 28 and 56 following GnRH-RS than EB-RS and no-RS. The final pregnancy rate was higher following EB-RS treatment than no-RS or GnRH-RS treatment (95.0, 88.3, and 88.6%; P<0.05). In conclusion, EB-RS enhanced reproductive performance of anestrous cows compared to no-RS.

Anestrus↗
PubMed1988

Fertility and hormonal responses to temporary relief of heat stress in lactating dairy cows.

The influence of temporary cooling on pregnancy rate and ovarian secretion of cortisol, estradiol and progesterone in Holstein cows was evaluated during the months of June to September. Cows were randomly assigned to one of five treatment groups: 1) evaporative cooling, 8 d; 2) evaporative cooling, 16 d; 3) refrigerated air conditioning, 8 d; 4) refrigerated air conditioning, 16 d and 5) controls maintained outdoors with access to shade. Estrus was synchronized by giving two injections of prostaglandin (25 mg). Cows in the cooled groups were placed in box stalls at the time of the second prostaglandin injection, allowing them to be cooled for approximately 3 d prior to breeding. Blood samples were taken on days 0, 5, 10, 15, 20 and 25 postbreeding and serum was analyzed for estradiol, cortisol, progesterone and a pregnancy-specific protein. Pregnancy rates as determined by palpation per rectum at 40 to 60 d post breeding were not different between cows in cooled treatments, regardless of duration or type of cooling. Pregnancy rate was higher (P<0.05) in cooled as compared to control cows. Serum progesterone concentrations were higher on Day 15 in cooled cows as compared to control cows. No differences in serum estradiol or cortisol concentrations were observed between cooled and control cows. Pregnancy-specific protein determinations indicated that 50% of both cooled and control cows conceived. Results indicate that temporary cooling increased pregnancy rates by increasing embryonic survival rates.

Journal Article↗
PubMed1988

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↗
PubMed1997

In vitro development of DNA-injected embryos co-cultured with goat oviduct epithelial cells in Korean native goats (Capra hircus aegagrus).

In vitro development of Korean native goat embryos was investigated in 2 different culture systems with and without goat oviduct epithelial cells (GOEC). Estrus was synchronized by inserting intravaginal progestagen-impnegnated sponge (Veramix) containing 60 mg medroxyprogesterone acetate (MAP) for 14 d. Superovulation was induced with follicle stimulating hormone (FSH). Goat ova were surgically obtained by retrograde flushing the oviducts of does at 66 to 68 h after MAP removal. Mean number of recovered ova per doe was 7.28 +/- 3.91, and the proportion of fertilized embryos in recovered ova was 66.5% (121/182 ). Fertilized embryos were cultured for 9 d in CR1aa medium supplemented with 10% estrous goat serum (EGS) at 38.5 degrees C, 5% CO(2) in air. There was no difference in development of the embryos to the morula stage between the 2 culture systems (84.4 and 84.0%, respectively). However, developmental rate to blastocysts (65.6%) of the embryos co-cultured with GOEC was significantly higher than of those (12.0%) cultured without GOEC (P < 0.001). Goat zygotes were injected with bovine beta-casein/human lactoferrin cDNA fusion gene (pBL1). When the DNA-injected embryos were co-cultured with GOEC, developmental rates of the embryos to the morula and blastocyst stages were 82.9 and 36.6%, respectively. The results obtained in this study indicate that "blocking" of in vitro development of Korean native goat embryos appears to occur at the morula stage, but can be overcome to some extent by co-culture with GOEC. In the co-culture system, DNA-injected goat embryos could successfully develop to normal hatching blastocysts.

Journal Article↗
PubMed1998

Cleavage, development and competence of sheep embryos fertilized by intracytoplasmic sperm injection and in vitro fertilization.

More abnormal fertilization has been found in sheep oocytes after intracytoplasmic sperm injection (ICSI) than after in vitro fertilization (IVF). Although the birth of a normal lamb has been reported, the efficiency of blastocyst production is low. We therefore evaluated the cleavage, development and viability of sheep embryos obtained from ICSI, IVF and sham injection. In vitro matured oocytes either injected or inseminated with spermatozoa were assessed for cleavage 1 and 4 d after injection or insemination, and for development to blastocyst after 7 d of culture. A total of 699 oocytes was injected (ICSI); 198 (30.6%) were activated and 55 (8.5%) developed to the blastocyst stage. Of the 17 recipient ewes with 1, 2, 3 or 4 embryos, 15 (88.2%) were pregnant on Day 18; of these 17 recipients, 7 (41.1%) and 6 (35.2%) ewes remained pregnant on Days 45 and 110, respectively. Two normal lambs were born, one ewe died on Day 110 with 2 normal male fetuses, another ewe aborted on Day 90 and 4 pregnancies were maintained. A total of 517 oocytes was inseminated (IVF); 296 (62%) were activated and 90 (18.8%) reached the blastocyst stage. A total of 19 ewes received 1, 2, 3 or 4 embryos; of these, 13 (68.4%) were pregnant on Day 18, 8 (42.1%) ewes remained pregnant on each of Days 45 and 110. Three ewes delivered 5 lambs. Five pregnancies were maintained. A total of 156 oocytes was sham injected, 38 (24.3%) were activated and no blatocysts were obtained after culture. The results of this study showed that blastocysts obtained after ICSI are potentially viable and are not a result of parthenogenesis.

Animals↗
PubMed1998

Determination of early pregnancy and embryonic growth in goats by transrectal ultrasound scanning.

Ultrasonography has been shown to be a useful tool for pregnancy diagnosis and the study of embryonic growth in mammals. The objectives of this study were 1) to evaluate the use of real-time B-mode ultrasonography for early pregnancy diagnosis in goats, 2) to define criteria for accurate diagnosis of pregnancy, and 3) to monitor the embryonic growth ultrasonically until Day 40 after mating. Estrus was synchronized in 16 cyclic Anglo-Nubian goats with a single injection of cloprostenol (125 micrograms, i.m.). Estrous females were randomly assigned into 2 groups: 1) goats mated by a vasectomized male (n = 5; MV group), and 2) goats mated by an intact male of proven fertility (n = 11; MF group). Transrectal ultrasonographic examinations with a 5 MHz linear array transducer were performed from Days 13 to 40 post mating. The evaluated parameters included the appearance of nonechogenic areas in the uterus, presence of embryo(s), crown-rump length of embryo and embryonic heart rate (beats/min). On Day 18, the mean (+/- SEM) diameter of nonechogenic areas was 1.5 +/- 0.3 mm in the MV group and 4.0 +/- 0.5 mm in the MF group (P < 0.01). In 36% of the pregnant does these areas were less than 3 mm. The mean (+/- SEM) day of the first detection by means of heartbeats of at least 1 embryo was 20.7 +/- 0.5 d (range, Days 19 to 23). From Days 19 to 38 of pregnancy, crown-rump length was best represented by a linear regression (Y = -2.23 + 0.13X; r2 = 0.94; P < 0.05). Crown-rump length on the day of the first detection of an embryo was 5.3 +/- 0.3 mm, reaching 34.2 +/- 0.6 mm on Day 40. Mean (+/- SEM) heartbeat rate was 168.3 +/- 2.8 beats/min on Day 21, decreasing to 158.3 +/- 2.0 beats/min on Day 40. Detection of the caprine embryo by ultrasonography and confirmation of its viability by heartbeats was shown to be a reliable method for early pregnancy diagnosis in Anglo-Nubian goats. Ultrasonic measurement of crown-rump length was useful in predicting the age of the embryo.

Animals↗
PubMed1998

Morphology of porcine cumulus-oocyte-complexes depends on the stage of preovulatory maturation.

The aim of this investigation was to determine the relationship between the morphology of the cumulus-oocyte-complexes (COCs) and the meiotic configuration of oocytes as an LH peak mimicked by hCG. Estrus was synchronized in a total of 29 crossbred Landrace gilts by feeding Regumate for 15 d and administering 1000 IU PMSG. The LH peak was simulated by treatment with 500 IU hCG at 80 h after PMSG. Endoscopic oocyte recovery was carried out 2 h before and 10, 22 and 34 h after hCG. Only macroscopically healthy follicles with a diameter of more than 5 mm were punctured. Altogether, 410 follicles from 57 ovaries were punctured and 251 COCs were aspirated. Oocyte recovery rate increased from 48.5% (P < 0.01) of the early, not yet preovulatory follicles (2 h before hCG) to 80.8% of late preovulatory follicles (34 h after hCG). Cumulus morphology in COCs recovered 2 h before and 10 h after hCG was heterogeneous, with most (72.9 to 57.4%; P < 0.01) showing a compact or slightly expanded cumulus. Starting at about 22 h after hCG, COC morphology changed dramatically (86.7% of COCs with expanded cumulus; P < 0.01), and 34 h after hCG, 98.3% of the COCs had only an expanded cumulus. The percentage of oocytes with a mature meiotic configuration increased (11.2; 7.1; 41.4 and 70.2%, respectively, n = 238 oocytes; P < 0.01) as the interval post hCG increased (-2, 10, 22, 34 h, respectively). Meiotic configuration was related to COC morphology: compact COCs--88.9% diplotene, expanded COCs--53.8% metaphase II (M-II), and denuded oocytes--69.2% degenerated chromatin. These results indicate that there is a relationship between oocyte recovery rate, COC morphology, and meiotic configuration and preovulatory follicle maturation after the application of hCG.

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