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PubMed2003

Pattern and manipulation of follicular development in Bos indicus cattle.

Bos indicus cattle are widespread in tropical regions due to their adaptation to these environments. Although data on reproductive performance have indicated both inferior and superior results for B. indicus cattle, there is little doubt that B. indicus cattle are superior than Bos taurus cattle when they are both kept in tropical or subtropical environments, where stressors like hot temperatures, humidity, ectoparasites and low quality forages are greater. Reproductive endocrinology and oestrus behaviour of the B. indicus cattle have been studied for over 30 years; however, the application of technologies such as real time ultrasonography and Heat-Watch systems has expanded our knowledge on the ovarian follicular-wave dynamics during the oestrous cycle and the time of ovulation. Ovarian follicular dynamics in B. indicus cattle is characterised by the occurrence of two, three or sometimes four waves of follicular development. While dominance is similar to that in B. taurus cattle, maximum diameters of the dominant follicle and CL are smaller than those reported in B. taurus and are probably due to a lower capacity for LH secretion than in B. taurus. Duration of oestrus is approximately 10 h and the interval from oestrus to ovulation is about 27 h. However, the variability in response to prostaglandin F2alpha (PGF) treatments and the difficulty for oestrus detection in B. indicus cattle have limited the widespread application of artificial insemination (AI) and emphasizes the need for treatments that control follicular development and ovulation. Follicular-wave development in B. indicus cattle can be controlled mechanically by ultrasound-guided follicle ablation, or hormonally by treatments with GnRH or oestradiol and progestogen/progesterone in combination. Treatments with GnRH plus PGF and a second GnRH (synchronization protocol known as Ovsynch) or oestradiol benzoate (known as GPE) have resulted in acceptable pregnancy rates after fixed-time AI (FTAI) in cycling cows, but results were lower in heifers and cows in postpartum anoestrus. Alternatively, treatments with oestradiol and progestogen/progesterone releasing devices resulted in synchronous emergence of a new follicular wave, and a second oestradiol or GnRH treatment after device removal resulted in synchronous ovulation and acceptable pregnancy rates to FTAI. Furthermore, oestradiol and progesterone treatments combined with eCG (given at the time of device removal) increased pregnancy rates in suckled B. indicus cows and may be useful for the treatment of cows in postpartum anoestrus. In summary, exogenous control of luteal and follicular development facilitates the application of assisted reproductive technologies in B. indicus cattle by offering the possibility of planning AI programs without the necessity of oestrus detection and without sacrificing the overall results.

Animals↗
PubMed1987

Fertility of pasture bred mares in synchronized oestrus.

Oestrus was synchronized in 220, 300 and 272 mares in 1983, 1984 and 1985 respectively. Mares were given two injections of 250 micrograms fenprostalene 15 days apart except in 1983 and 1984 when 56 and 53 of the synchronized mares were given 1-10 daily injections of 150 mg progesterone and 10 mg oestradiol-17 beta to delay and synchronize post-partum oestrus. At 2 days after the second PG injection or 7 days after the last progesterone + oestradiol treatment, mares were divided into groups of 15-21, and each group was placed in a separate pasture with a stallion for 7 weeks. Pregnancy rates were 87.7, 93.7 and 97.1%, and foaling rates were 72.3, 89.7 and 94.1% in 1983, 1984 and 1985 respectively. The number of abortions occurring mainly between 3 and 6 months of gestation varied from 34 (17.8%) in 1983 to 12 (4.3%) in 1984 and 8 (3.0%) in 1985.

Abortion, Veterinary↗
PubMed2000

Comparing ovulation synchronization protocols for artificial insemination in the scimitar-horned oryx (Oryx dammah).

Ovarian response and pregnancy success in scimitar-horned oryx (n=28) were compared, following treatment with two synchronization protocols and fixed-time artificial insemination (AI) with frozen-thawed semen. Each oryx received two injections of 500 microg of prostaglandin-F(2alpha) analogue (PGF(2alpha)-only) 11 days apart, and half received PGF(2alpha) in combination with an intravaginal progesterone-releasing device (CIDR11+PGF(2alpha)). Semen was collected by electroejaculation from anaesthetised adult oryx and cryopreserved. Anaesthetised females were transcervically inseminated 56.0+/-1.1 h (+/-S.E.M.) after PGF(2alpha) injection and/or device withdrawal using 28.0+/-1.5x10(6) motile thawed sperm. Ovarian endocrine response was monitored in 20 females by analysing faecal oestrogen and progesterone metabolites. Periovulatory oestrogen peaks were detected in 19/20 (95%) females after synchronization. There were no between-treatment differences in oestrogen concentrations or peak characteristics (P0.05). Luteal development after synchronization was delayed in half the progesterone treated (CIDR11+PGF(2alpha)) females, and faecal progestin excretion profiles indicated that the ovulatory follicle associated with synchronization either failed to ovulate or to fully lutenise. Pregnancy was diagnosed by ultrasonography and/or rectal palpation and was monitored by faecal progestin excretion. More (P=0. 013) pregnancies resulted from the PGF(2alpha)-only treatment (37.5%, 5/14) than from the CIDR11+PGF(2alpha) treatment (0/14), and four healthy scimitar-horned oryx calves were born, three after gestation intervals of 247 days and one after 249 days.

Administration, Intravaginal↗
PubMed2004

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.

Abortion, Veterinary↗
PubMed2005

[Factors influencing conception rate after synchronization of ovulation and timed artificial insemination--a review].

This review describes factors that affect conception rate after synchronization of ovulation and timed artificial insemination. Intervals of 7 days between GnRH and PGF2alpha, 48 hours to the second GnRH treatment and a further 16 to 20 hours to the timed insemination have been proven to be most effective. Conception rates (CR) increase as lactation progresses up to 100 days in milk. Primiparous cows have higher CR than older cows. Anovular cows at the start of the synchronization protocols have poor CR. These are highest for cows started in early dioestrus. While poor body condition and some post partum and post insemination health disorders have negative effects on the CR, a significant effect of postpartum chronic endometritis could not be demonstrated. High milk yield was also not shown to have a negative effect on CR in almost all studies, while the negative effect of heat stress on fertility is also found in Ovsynch cows. However, the negative effects of high milk yields and heat stress on AI submission rates are overcome by the timed insemination protocol.

Animals↗
PubMed2000

Survival and viability of vitrified in vitro and in vivo produced ovine blastocysts.

Ovine blastocysts were produced by maturation, fertilization and in vitro culture (IVM/IVF/IVC) of oocytes from slaughtered adult and prepubertal ewes and collection from superovulated and inseminated adult animals. Dulbecco's PBS supplemented with 0.3 mM Na Pyruvate and 20% FCS was used as the basic cryopreservation solution. The embryos were exposed to the vitrification solution as follows: 10% glycerol (G) for 5 min, then 10% G +20% ethylene glycol (EG) for 5 min. Embryos were placed into 25% G + 25% EG in the center of 0.25- mL straws and plunged immediately into LN2. Warming was done by placing the straws into a water bath at 37 degrees C for 20 sec, and their contents were expelled into a 0.5 M sucrose solution for 3 min; the embryos were then transferred into 0.25 M and 0.125 M sucrose solution for 3 min each. Warmed blastocysts were transferred to the culture medium for 24 h. Survival was defined as the re-expansion of the blastocoele. All surviving blastocysts were transferred to synchronized recipient ewes, and the pregnancy was allowed to go to term. Of 68 vitrified in vitro produced blastocysts, 46 re-expanded (67.6%) and 10 lambs were born (14.7%). From the 62 in vivo derived and vitrified embryos, 52 re-expanded (83.8%) and 39 lambs were born (62.9%). The lambing rate of in vitro produced fresh transfer embryos was 40% (20 lambs/50 blastocysts transferred), and of the 32 in vivo derived blastocysts and transferred fresh, 26 lambs were born (81.2%). The results indicate that in vitro produced embryos can be successfully cryopreserved by vitrification.

Animals↗
PubMed1991

Artificial insemination of red deer (Cervus elaphus) with frozen-thawed wapiti semen.

Semen collected from wapiti (Cervus elaphus) in Canada in 1983 was frozen in two extenders. In 1988, the semen was used to inseminate 200 red deer hinds on 2 farms in New Zealand. Oestrus was synchronized in the hinds with progesterone-impregnated intravaginal devices (CIDR); 200 iu pregnant mares' serum gonadotrophin was given to each hind on Day 11. The CIDRs were removed on Day 12 at 20/h, as the numbers of the hinds were recorded. On Day 14, 54-56 h after CIDR removal, the hinds were brought into the yards in the same batches and laparoscopically inseminated. Semen from three sires was used. The overall conception rate was 51%. Gestation length ranged from 239 to 247 days. One hind was lost at calving, 3 calves had to be hand raised and there were 2 neonatal calf deaths.

Animals↗
PubMed1997

Hormonal requirement for blastocyst implantation and a new approach for anti-implantation strategy.

There is a growing awareness of a need for developing novel methods of contraceptive technology which should not only be effective in providing protection against conception but also take into consideration the reproductive health issues confronting men and women. This paper considers the process of embryo implantation as one such potential target. The hormonal basis of embryo implantation in primates has been discussed to indicate that progesterone, and not estrogen, from ovarian source is the primary determinant of embryo-endometrial maturation and their synchronization for implantation. Thus, low dose administration of the anti-progesterone, mifepristone, during early luteal phase has been shown to be an effective anti-implantation approach to for fertility control. Furthermore, the dissociation of endometrial-hormonal synchrony at the time of blastocyst implantation following the post-ovulatory mifepristone administration has been shown to be the physiological basis of its anti-implantation effect with undisturbed circulatory hormone profiles and ovarian functions. Further studies are required to appreciate the full potential and to mollify the limitations of this approach.

Animals↗
PubMed2005

The effect of internal and external factors on bovine embryo transfer results in a tropical environment.

The objectives of this work were to determine the effect of external (synchronization methods, month, embryo origin and farm effects) and internal factors (age and size of CL, embryo development and quality score, synchronization methods, age of recipient, quality of transfer and reuse of recipients) on a commercial embryo transfer program in a tropical environment. In the program 1466 Holstein-Friesian purchased embryos were implanted to zebu/European crossbred recipients under field conditions. There were 502 pregnancies detected in this large-scale extension programme. Synchronization methods, month, embryo origin, and farm effects were found to have affected the success rate of embryo transfer. Due to the hot climate and large distances between recipient farms, seasonal effects, reused recipient pregnancy results and the effect of embryo development stage differed from previously reported results. Investigation by ultrasonograph showed that embryo loss occurred before 35 days of pregnancy. Under field conditions, routine fetal sexing resulted in <5% misidentification. In conclusion, under tropical conditions external factors have a major influence on the results of pregnancy from embryo transfer.

Abortion, Veterinary↗
PubMed1981

[Single administration of a progesterone preparation during early gravidity of gilts following synchronized ovulation and induction of puberty to lower the age of first insemination].

The action of one single injection of 62.5 mg of hydroxy-progesterone-capronate on the 14th day after first insemination was tested for the purpose of defining the fertility performance of 180 gilts with synchronised ovulation and induced puberty. Synchronised ovulation caused significant rise in litter size and enhancement in gravidity rates. By comparison with a control group, the number of piglets born additional to each first insemination was 2.3. Induction of puberty to lower first-insemination age was of significant positive effect only on the pregnancy result, and somewhat fewer piglets were actually born. Nevertheless, the surplus birth figure to each first insemination was 2.1, as compared to untreated sows. The positive effect on puberty-induced animals was inversely proportional to daily weight rise.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed1988

Oestrus synchronization in dairy heifers using a progesterone releasing intravaginal device.

This paper describes a pilot trial carried out, to investigate the use of progesterone releasing intravaginal device(PRID) in controlled breeding in heifers under South African conditions. PRID's containing progesterone and oestradiol benzoate were employed for oestrus synchronization and reproductive management in ten 18-month-old, well-managed, heifers in a commercial Transvaal highveld dairy herd. PRID's were inserted into the vagina of each animal and removed after 12 days. Oestrus observation was done continuously and on the first observed oestrus the heifers were artificially inseminated once. Oestrus detection continued normally for returns to oestrus. Pregnancy was confirmed by rectal palpation eight weeks after breeding if no return to oestrus had occurred. The incidence of clinical oestrus within 3 days after removal of the PRID's (defined as the oestrus response) was 90%. The conception or pregnancy rate following the first artificial insemination was 77.8%.

Administration, Intravaginal↗
PubMed1987

Fertility of stallion semen frozen in 0.5-ml straws.

Semen of 2 pony stallions was frozen by 2 methods in 0.5 ml PVC straws. The fertility of the frozen-thawed semen was evaluated by inseminating 60 mares during 69 oestrous cycles. An overall single cycle pregnancy rate of 55% was achieved. Freezing method, stallion, insemination during steroid-synchronized oestrus or insemination only every 2nd day during oestrus did not significantly influence pregnancy rates. Pregnancy rates were significantly improved from a mean 44% to a mean 73% when the mean number of progressively motile spermatozoa per insemination was increased from 175 x 10(6) to 249 x 10(6). It is concluded that the simpler freezing technique will yield satisfactory pregnancy rates when semen with a post-thaw progressive motility of 30% is used for AI. Starting when ovulation is anticipated to occur within the next 48 h mares should be inseminated every 2nd day with at least 220 x 10(6) progressively motile spermatozoa per insemination until ovulation is confirmed.

Acrosome↗
PubMed2005

A new approach to enhance reproductive performance in sheep using royal jelly in comparison with equine chorionic gonadotropin.

The objective was to compare the effects of royal jelly (RJ) and eCG treatments on reproductive performance of ewes synchronized using intravaginal progesterone-releasing devices. Forty-two cycling Awassi ewes were treated intramuscularly (i.m.) with 15 mg PGF2alpha. On the following day, all ewes were administered with CIDR-G for 12 days and were randomly allocated to three (RJ, eCG and control) groups of 14 ewes each. Ewes in the RJ-treated group received daily i.m. treatments of 400mg RJ during the period of CIDR-treatment. Each ewe in the eCG-treated group received an i.m. treatment of 500 IU eCG at the time of CIDR-G removal (day 0) and no further treatment was given to ewes in the control group. Ewes were exposed to four fertile rams for 72 h, from the time of CIDR-G removal, and checked for breeding marks at 6-h intervals. Blood samples were collected from day -13 until day 0 and thereafter until day 19 for progesterone analysis. Royal jelly treatment resulted in a greater rate of decline and lower (P<0.02) progesterone concentrations between days -10 and 0 than eCG-treated and control ewes. Expression of estrus was similar among the three groups and intervals to onset of estrus were shorter (P<0.01) in RJ-treated (31.3h) and eCG-treated (29.8h) than control (41.3h) ewes. First-cycle pregnancy and lambing rates were greater (P<0.05) in RJ-treated (71.4 and 71.4%) and eCG-treated (85.7 and 78.6%) than in control (42.9 and 35.7%) ewes, respectively. Results demonstrate that the treatments of RJ and eCG in conjunction with CIDR-G were similarly effective in induction of estrus and improvement of pregnancy and lambing rates.

Animals↗
PubMed2004

Pseudopregnancy in Saanen goats (Capra hircus) raised in Northeast Brazil.

The prevalence of pseudopregnancy over 44 months was investigated in 23 Saanen goats raised in Northeast Brazil during continuous oestrous cycling (cyclic group) or after synchronization of oestrus (synchronized group). The goats were monitored by ultrasonography and their plasma progesterone profile. The overall prevalence of pseudopregnancy was 30.4% (7/23). In the cyclic group, 28.6% (4/14) of goats showed pseudopregnancy, while in the synchronized group the prevalence was 33.3% (3/9). There was no significant difference between the groups (p>0.05). The mean (+/- SD) length of pseudopregnancy, as shown by the progesterone profile, was 121.6 +/- 33.5 days, ranging from 70 to 155 days. The study defined the prevalence of pseudopregnancy in Saanen goats raised in Northeast Brazil for the first time. This finding identified a major problem for this breed, as without treatment such animals remain unproductive until the spontaneous resolution of the condition. More research seems desirable to ascertain the prevalence of this condition in other breeds in this region of Brazil.

Animals↗
PubMedDate not supplied

Plasma progesterone levels during oestrous cycle and their relationship with the ovulation rate in Red Sokoto (Maradi) goats.

Twenty-five 2-3-year-old cycling does weighing 17-25 kg were obtained from semi-nomadic farmers and managed under controlled conditions while simulating the traditional management system. Oestrus was synchronized using progestogen impregnated vaginal pessaries. Blood samples were collected daily for progesterone assay from the day of pessary withdrawal up to one complete oestrous cycle. Oestrus was checked twice daily using vasectomized bucks. Ovulation rate was determined by direct observation of the ovaries following laparotomy on day 5-7 of the oestrous cycle. Following oestrus synchronization, mean ovulation rate was 1.68 +/- 0.13. Mean oestrous cycle length and duration of oestrus were 21.30 +/- 0.28 days and 21.37 +/- 0.24 hours respectively. Plasma progesterone concentrations ranged from non-detectable levels on the day of oestrus to 5.2 +/- 0.28 ng ml at mid-cycle. The duration of elevated progesterone level (greater than 2 ng/ml) was about 12 days. The peak progesterone values did not differ between animals with different ovulation rates. However, the plasma progesterone concentration during the early cycle (days 0-6) was significantly lower in the single ovulators compared with others. There were no major differences in plasma progesterone levels during the oestrous cycle of Red Sokoto does with different ovulation rates.

Animals↗
PubMed2000

Effect of long-term selection for early postnatal growth rate on survival and prenatal development of transferred mouse embryos.

Reciprocal embryo transfer procedures were performed among mouse selection lines to examine prenatal maternal effects on survival and development of transferred embryos. Mice were from generations 28 and 29 of an experiment to select for (i) increased body weight again from 0 to 10 days (E+); (ii) decreased body weight gain from 0 to 10 days (E-); or (iii) a randomly bred control line (C). A total of 118 embryo transfer procedures performed 12 h after conception resulted in 983 progeny born to 89 litters. There was a 39% overall embryo survival rate and 75% overall pregnancy success rate. Response to superovulation and oestrous synchronization was significantly lower (P < 0.01) in the E+ line. E+ individuals that did superovulate produced an average of 37 oocytes per flush, which was significantly higher than in the control line mice (29 oocytes per flush; P < 0.01). The ability to complete pregnancy successfully was not influenced by uterine environment or embryo-uterine interaction. In contrast, embryo survival in successful pregnancies was significantly affected by uterine environment. There were large maternal effects for body weight and tail length at birth; E+ recipients produced pups that were significantly larger than E- recipient pups (P < 0.01), which in turn were significantly larger than pups gestated by control recipients (P < 0.01).

Animals↗
PubMed1997

Variation between ejaculates in the fertility of frozen ram semen used for cervical insemination of Merino ewes.

Two field experiments were conducted to investigate the amount of variation between rams, and between ejaculates within rams, in the fertility of frozen-thawed semen used for cervical insemination. Individual ejaculates from seven Merino rams were frozen and used to cervically inseminate Merino ewes at a synchronized oestrus at two sites. In Experiment 1 (N = 491), pregnancy rates (determined 70-80 days after insemination) for individual rams ranged from 1.8 to 11.9%. Individual ejaculates produced pregnancy rates between 0 and 21.4%. Overall conception rate was 6.5%. No significant differences were detected. Pregnancy rates for the same rams in Experiment 2 (N = 449) varied from 10.3 to 32.6% (P < 0.05). Ejaculate pregnancy rates ranged between 0 and 60% (P < 0.01). Fertility of individual ejaculates within rams differed for three of the seven rams used (P < 0.01). It is concluded that considerable variation in fertility of frozen ram semen exists between ejaculates within rams as well as between rams. Possible sources (biological and arising from freezing artefacts) of such variation and their practical implications are discussed.

Animals↗
PubMed2003

Timing of ovulation and conception rate in primiparous and multiparous cows after synchronization of ovulation with GnRH and PGF2alpha.

Conception rates after Ovsynch have been higher in primiparous than in multiparous cows. The objective of this study was to investigate whether this difference might be due to differences in ovulation rate or follicular size. The experiment was conducted with 136 Holstein Frisian cows from a commercial herd in Brandenburg, Germany. All cows were synchronized using Buserelin (GnRH analogue) at day -10, Tiaprost (PGF2alpha analogue) at day -3 and again GnRH at day -1. Timed artificial insemination (TAI) was carried out 16-20 h after the second dose of GnRH on day 0. Milk samples for analysis of milk progesterone were obtained on days -17, -10, -3 and at TAI. Progesterone concentrations were used to determine the stage of oestrus cycle at the start of the synchronization protocol and to investigate the presence of functional luteal tissue before treatment with PGF2alpha and TAI. All animals were examined by ultrasound at the second treatment with GnRH, at AI, 8 and 24 h after AI. Overall synchronization rate (proportion of cows with an ovulation within 40 h after GnRH) was 86.8% in primiparous and 88.2% in multiparous cows, respectively. Ovulation occurred earlier in primparous than in multiparous cows (p < 0.05) and ovulatory follicles were smaller. Conception rates were numerically higher in primiparous cows but the difference was not significant. Cows that displayed signs of oestrus on day -1 and received an additional AI on this day were more likely to conceive than cows that only received TAI 16 to 20 h after GnRH2. It is concluded that ovulation occurs earlier in primiparous than in multiparous cows after Ovsynch. However, a significant relationship between these differences and the probability of conception could not be established.

Animals↗