Effect of breeding season on fertility of sheep following estrus synchronization and fixed-time artificial insemination under field conditions in semi-arid tropical region

Accelerated lambing system is heavily reliant on reproductive technologies meant to enable off the season breeding in sheep. Therefore, the present study was programmed to assess the effect of breeding season (BS) on fertility of sheep following estrus synchronization (ES) and fixed time artificial insemination (FTAI). A total of 248 and 365 ewes were synchronized and inseminated during the BS (Febuary–March and July–September) and non-breeding season (NBS) respectively, during 2012–14. Synchronization of estrus was done by AVIKESIL-S, intra-vaginal progesterone sponges kept in situ in vagina for 12 days. 200 IU eCG was administered intramuscularly on 12th day after sponge withdrawal. FTAI was performed twice in ewes exhibiting signs of estrus at 48 and 56h after sponge removal, using liquid chilled semen of Patanwadi/Malpura rams containing 100 million sperm. Breeding season had no significant (p<0.05) effect on estrus synchronization. The estrous responses during the BS and NBS were 84.68% and 83.29% respectively. The lambing percentage during BS was 66.67%, which is significantly (p<0.05) higher than the lambing percentage of NBS (57.57%). Although, the lambing percentage in NBS maneuvered ewes were lower than the BS ewes but still the technology can be used to offset the effect of anestrus and to augment production in sheep.     

Effect of PMSG dosage on the reproductive performance of adult ewes and ewe lambs bred at a progestagen-PMSG synchronized estrus

The effect of dose of pregnant mares' serum gonadotropin (PMSG) on the reproductive performance of adult ewes and ewe lambs and lamb survival at birth after treatment with fluorogestone acetate (FGA)-impregnated intravaginal sponges and PMSG (250 IU or 500 IU) to synchronize estrus was evaluated. Ewes were exposed to rams for breeding at the synchronized and subsequent estrous cycles. The flock, comprised of three synthetic strains and two control breeds, was maintained in a controlled environment and exposed to an artificial light regimen which alternated at 4-mo intervals from 16h of light daily to 9h of light daily. Trials were conducted during January, May and September at the end of a 9-h daylength cycle. Adult ewes were bred in May and 8 mo later in January. Ewe lambs were bred in September at 6.5 to 7.5 mo of age. The overall reproductive performance of the adult ewes was similar at the two breedings: fertility approximately 90%, prolificacy approximately 2.7, fecundity approximately 240% and lambs born alive approximately 2.4. Dosage of PMSG had no effect. Reproductive performance of ewe lambs was lower and there was a strain x treatment interaction, suggesting greater variability in response. The results indicate there is no advantage to using a higher dose of PMSG in ewes with a natural relatively high fecundity. Moreover, the use of the artificial photoperiod appears to overcome the natural seasonal variation in reproductive performance.     

Insemination management for a one-injection prostaglandin F(2)alpha synchronization system. II. One versus two inseminations following detection of estrus

Following detection of estrus in an estrus synchronization system, 216 dairy heifers were inseminated (A.I.) randomly either soon after detected estrus (1X) or soon after detected estrus and again 10 to 12 h later (2X). Average h from detection of estrus to A.I. was 1.8+/-0 for 1X and 1.1+/-0 and 11.1+/-0.4 for 2X. During the regimen, heifers were checked visually for estrus daily for five consecutive days with 16.0 and 17.3% showing estrus and receiving A.I. in the 1X and 2X groups, respectively. Those not seen in estrus were injected with 25 mg PGF(2)alpha with observations for estrus and A.I. continuing for five more days. Response rates as indicated by estrus following prostaglandin F(2)alpha (PGF(2)alpha) were 74.7 and 75.8% for 1X and 2X, respectively. Percentages of heifers in estrus <24, 25 to 48, 49 to 72, 73 to 96 and >96 h after PGF(2)alpha were 3.7, 22.8, 47.1, 15.4 and 11.0, respectively. Based on rectal palpation for pregnancy between 45 and 60 days after A.I., conception rates of 70.2% for 1X and 68.6% for 2X did not differ significantly (P>0.05). Progesterone concentrations at injection for heifers not responding to PGF(2)alpha were lower than was seen in responding heifers (2.7 vs 5.8 ng/ml) (P<0.01). Data from the present experiment supports the conclusion of an earlier experiment that satisfactory conception can be achieved with a single, established daily insemination period.     

Insemination management for a one-injection prostaglandin F(2)alpha synchronization regimen. I. One daily insemination period versus use of the a.m./p.m. rule

Following detection of estrus in a one-injection prostaglandin F(2)alpha (PGF(2)alpha) synchronization regimen, 261 dairy heifers were randomly inseminated (A.I.) either once between 0800 and 0900 h daily (a.m.) or about 12 h after detection of estrus (a.m./p.m.). During the regimen, 31.8 and 33.3% for the a.m./p.m. and a.m. groups, respectively showed estrus and received A.I. during the pre-PGF(2)alpha period. The remaining heifers were injected with PGF(2)alpha with 95.6% from a.m./p.m. and 96.5% from a.m. showing estrus and receiving A.I. within five days after PGF(2)alpha. Pregnancy rates of 62.9% for a.m./p.m. and 62.0% for a.m. did not differ. Progesterone at the time of injection was similar between groups and was not correlated with either response to PGF(2)alpha or fertility. Percentages of heifers in estrus <24, 25-48, 49-72, 73-96 and >96 after PGF(2)alpha were 4.7, 30.2, 45.6, 14.3 and 5.3, respectively, with a mean time of 61.0+/-1.9 h. Satisfactory conception rate was attained with a.m. insemination.     

Successful artificial insemination in the giant panda (Ailuropoda melanoleuca) at ueno zoo

Successful breeding of the giant panda (Ailuropoda melanoleuca) following artificial insemination was achieved at the Ueno Zoo in 2 consecutive years (1985 and 1986). The first cub, born in June 1985, unfortunately died 43 hours after birth from being crushed by the mother panda; the second cub, born in June 1986, has been growing in good health. Electroejaculation and artificial insemination procedures were performed after immobilization with diazepam (0.1 mg/kg) and ketamine HCL (4.0–5.0 mg/kg). Semen of the male panda was collected by electroejaculation using a rectal probe with a diameter of 2.0 cm and with eight rings as electrodes. Stimulation of the male was given with 3 V (30–40 mA) over a 5-sec period with 5-sec intervals. The female panda exhibited estrus between late February and early March in 1985 and also between mid-january and early February 1986. Increased excretion of urinary total estrogen showed coincidentally at maximum behavioral estrus, and a gradual rise of pregnanediol level was followed by artificial insemination. The gestational length for the first pregnancy was 110 days and that of the second 121 days.     

The 9-day CIDR-PG protocol: Incorporation of PGF2α pretreatment into a long-term progestin-based estrus synchronization protocol for postpartum beef cows

A pilot experiment was designed to test the hypothesis that administration of PGF_2α before progestin treatment would allow for a reduced duration of progestin treatment in a long-term progestin-based estrus synchronization protocol. A modified presynchronization treatment was compared with a standard long-term controlled internal drug release (CIDR) treatment, and treatments were compared on the basis of ovarian follicular dynamics, estrous response rate, synchrony of estrus expression, and pregnancy rates resulting from timed artificial insemination (TAI) in postpartum beef cows. Estrous was synchronized for 85 cows, with cows assigned to one of two treatments based on age, days postpartum, and body condition score. Cows assigned to the 14-day CIDR-PG protocol received a CIDR insert (1.38 g progesterone) on Day 0, CIDR removal on Day 14, and administration of PGF_2α (25 mg im) on Day 30. Cows assigned to the 9-day CIDR-PG protocol received PGF_2α concurrent with CIDR insertion on Day 5, PGF_2α concurrent with CIDR removal on Day 14, and administration of PGF_2α on Day 30. In both treatments, split-time AI was performed based on estrous response. At 72 hours after PGF_2α (Day 33), cows having expressed estrus received TAI; cows that failed to express estrus by 72 hours received TAI 24 hours later (96 hours after PGF_2α on Day 34), with GnRH (100 μg im) administered to nonestrous cows. Estrus-detection transmitters were used from CIDR removal until AI to determine onset time of estrus expression both after CIDR removal and after PGF_2α. Ovarian ultrasonography was performed at CIDR removal on Day 14, PGF_2α on Day 30, and AI on Days 33 or 34. At CIDR removal on Day 14, diameter of the largest follicle present on the ovary was similar between treatments. The proportion of cows expressing estrus after CIDR removal tended to be higher (P = 0.09) among cows assigned to the 9-day CIDR-PG treatment (93%; 40 of 43) than among cows assigned to the 14-day CIDR-PG treatment (81%; 34 of 42). After PGF_2α, a significantly higher proportion (P = 0.02) of cows expressed estrus after synchronization with the 9-day CIDR-PG treatment (91%; 39 of 43) than the 14-day CIDR-PG treatment (69%; 29 of 42). Consequently, pregnancy rate to TAI tended to be increased (P = 0.09) among the 9-day CIDR-PG treatment (76.7%; 33 of 43) compared with the 14-day CIDR-PG treatment (59.5%; 25 of 42). In summary, a long-term CIDR-based estrous synchronization protocol for postpartum beef cows was enhanced through administration of PGF_2α at CIDR insertion and CIDR removal.     

Comparison of prostaglandin- and progesterone-based protocols for timed artificial insemination in sheep

The objective was to compare the reproductive performance of a new PGF_2α-based timed artificial insemination (TAI) protocol in sheep (Synchrovine®: two doses of PGF_2α, 7 d apart) to a traditional progesterone-eCG (P4-eCG) protocol, considering the effects of seminal state, AI-times, and AI-pathway. Three experiments involving 1297 multiparous Australian Merino ewes were done during the physiologic breeding season (location 32 °S-57 °W). Reproductive performance was assessed as non-return rate to service 21 d after AI (NRR21d), based on detection with androgenized wethers, as well as Fertility (pregnant/inseminated ewes), Prolificacy (fetuses/pregnant ewe), and Fecundity (fetuses/inseminated ewe), which were based on transabdominal ultrasonography 50 d after TAI. In Experiment 1, Synchrovine® treated ewes TAI cervically with fresh semen at 42, 48, or 54 h had similar NRR21d (0.51, 0.46, 0.57), Fertility (0.27, 0.31, 0.26), and Fecundity (0.29, 0.32, 0.27), all of which were lower (P < 0.05) than in a control P4-eCG group inseminated at 54 h (0.61, 0.48, 0.52, NRR21d, Fertility and Fecundity respectively). In Experiment 2, using chilled semen and cervical TAI, Synchrovine® treated ewes inseminated at 42 h yielded lower (P < 0.05) NRR21d, Fertility and Fecundity (0.28, 0.06, 0.06) compared to 48 (0.43, 0.24, 0.24) and 54 h (0.44, 0.22, 0.23). In Experiment 3 with chilled semen, Synchrovine® treated ewes TAI into the cervix at 51 or 57 h were similar in NRR21d (0.16 vs 0.20), Fertility (0.12 vs 0.14), and Fecundity (0.12 vs 0.15), respectively; but lower (P < 0.05) than P4-eCG treated ewes TAI at 54 h (0.34, 0.28, and 0.33 for NRR21d, Fertility and Fecundity respectively). Synchrovine® treated ewes intrauterine TAI at 51 or 57 h yielded similar NRR21d (0.51 vs 0.58), Fertility (0.43 vs 0.51), and Fecundity (0.45 vs 0.56) respectively, but lower (P < 0.05) results compared to P4-eCG treated ewes (0.75, 0.71, and 0.88 for NRR21d, Fertility and Fecundity respectively). In conclusion, AI-time in Synchrovine® treated ewes with fresh semen might be extended (42 to 54 h after the second PGF_2α), but should be delayed to 48-54 h with chilled semen and cervical AI. Independent of the seminal state, AI-time or AI-pathway, Synchrovine® yielded lower reproductive results than a conventional P4-eCG protocol.     

Synchronization of estrus and fertility in goats with norgestomet ear implants

Estrus was synchronized in 64 dairy goats in July with norgestomet ear implants. Half the does received ear implants that contained 6 mg norgestomet and the remaining does received implants that contained 3 mg. Implants were left in place for 11 days. Each doe received i.m. injections of 400 IU PMSG and 50 mug cloprostenol 24 hours prior to implant removal. Twenty-eight of 32 does (87.5%) that received 6 mg or 3 mg norgestomet exhibited onset of estrus within 24 hours of implant removal. All does had exhibited onset of standing estrus by 43 hours after implant removal. Does were hand-mated to fertile bucks twice daily while in standing estrus. There were no differences between does implanted with 6 mg or 3 mg in fertility to the induced estrus (74.2% vs 75% kidding), mean length of gestation (151.0 +/- 3.2 vs 151.6 +/- 2.0 days), mean number of kids per doe (2.1 +/- 0.8 vs 2.3 +/- 0.7) or in mean kid weights (3.10 +/- 0.80 vs 3.06 +/- 0.86 kg) (6 mg vs 3 mg, respectively). It was concluded that ear implants that contained 3 mg of norgestomet were equally as effective as implants that contained 6 mg for synchronization of estrus in dairy goats.     

Synchronization of estrus in cyclic beef heifers with the prostaglandin analog alfaprostol

Seventy-eight Hereford-Angus crossbred heifers were injected intramuscularly twice with 6 mg of alfaprostol^b in 6 ml of propylene glycol. On each representative day of a 20-day estrous cycle (estrus = Day 0), either three or four heifers received their first injection. The second injection was given 12 days after the first, regardless of the response to the first injection. Thirty-nine heifers were not treated. The first alfaprostol injection reduced serum progesterone to less than 1 ng/ml in all heifers injected after Day 4. A total of 79.5% ($\text{62}\text{78}$) of the heifers exhibited estrus by five days after the first injection. Average interval from injection to estrus was 63 hours. The second injection occurred on Days 6 through 16 for all but one heifer, with 75.6% ($\text{59}\text{78}$) falling on Days 8 through 11 of the estrous cycle. Estrus was detected in 93.6% ($\text{73}\text{78}$) of the heifers within five days after the second injection, with an average interval to estrus of 66 hours.Day of cycle at second injection did not affect the interval to estrus. Conception occurred in 79.4% ($\text{58}\text{73}$) of the heifers inseminated in the five days after the second injection. Occurrence of estrus and conception was no different in treated heifers after five days of the insemination period than in nontreated heifers after 21 days of the insemination period, where 94.9% ($\text{37}\text{39}$) were observed in estrus and 83.8% ($\text{31}\text{37}$) conceived. Overall percent conception for a 55-day insemination period was 89.7 ($\text{70}\text{78}$) for treated and 87.2 ($\text{34}\text{39}$) for nontreated heifers. Day of cycle at first or second injection did not affect conception after the second injection. Some signs of estrus were observed in 11 of the 16 heifers injected before Day 5.A second trial to determine if alfaprostol induced luteolysis early in the cycle was conducted. Twenty purebred Angus, Hereford, or Simmental heifers received either one or two injections of alfaprostol on either Day 1, 2, 3, or 4. Only five heifers showed any signs of estrus, and the three that were inseminated did not conceive. Subsequent cycle length indicated that luteolysis occurred in only one heifer.Data suggest that alfaprostol is an effective luteolytic agent in cyclic beef heifers after Day 4 and that two injections 12 days apart will effectively synchronize estrus in heifers when distributed throughout the cycle at the first injection without affecting conception rate.     

Problems and experiences in performing artificial insemination in bonobos (Pan paniscus)

A report is given on the problems and the procedure of artificial insemination in the bonobo (Pan paniscus). In addition, the different possibilities and methods of the process of collecting sperm, its conservation, and determining the time of ovulation are discussed, as well as the various insemination techniques and their usage under practical conditions in zoological gardens.     

Resynchronization with unknown pregnancy status using progestin-based timed artificial insemination protocol in beef cattle

Two experiments were designed to evaluate the use of resynchronization (RESYNCH) protocols using a progestin-based timed artificial insemination (TAI) protocol in beef cattle. In experiment 1, 475 cyclic Nelore heifers were resynchronized 22 days after the first TAI using two different inducers of new follicular wave emergence (estradiol benzoate [EB; n = 241] or GnRH [n = 234]) with the insertion of a norgestomet ear implant. At ear implant removal (7 days later), a pregnancy test was performed, and nonpregnant heifers received a dose of prostaglandin plus 0.5 mg of estradiol cypionate, with a timed insemination 48 hours later. The pregnancy rate after the first TAI was similar (P = 0.97) between treatments (EB [41.9%] vs. GnRH [41.5%]). However, EB-treated heifers (49.3%) had a greater (P = 0.04) pregnancy per AI (P/AI) after the resynchronization than the GnRH-treated heifers (37.2%). In experiment 2, the pregnancy loss in 664 zebu females (344 nonlactating cows and 320 cyclic heifers) between 30 and 60 days after resynchronization was evaluated. Females were randomly assigned to one of two groups (RESYNCH 22 days after the first TAI [n = 317] or submitted only to natural mating [NM; n = 347]). Females from the NM group were maintained with bulls from 15 to 30 days after the first TAI. The RESYNC-treated females were resynchronized 22 days after the first TAI using 1 mg of EB on the first day of the resynchronization, similar to experiment 1. No difference was found in P/AI (NM [57.1%] vs. RESYNC [61.5%]; P = 0.32) or pregnancy loss (NM [2.0%] vs. RESYNC [4.1%]; P = 0.21) after the first TAI. Moreover, the overall P/AI after the RESYNCH protocol was 47.5%. Thus, the administration of 1 mg of EB on day 22 after the first TAI, when the pregnancy status was undetermined, promotes a higher P/AI in the resynchronized TAI than the use of GnRH. Also, the administration of 1 mg of EB 22 days after the TAI did not affect the preestablished pregnancy.     

Reproductive studies of the Oryx

The genus Oryx comprises one species already extinct in the wild and others that are rapidly disappearing. It is important to understand the reproductive physiology of these species in order to ensure their successful captive propagation. It was determined behaviorally and hormonally that the scimitar-horned oryx's 21–22 d estrous cycle very closely resembled that of the domestic cow. Four females of three species (Arabian, scimitar-horned, and fringe-eared oryx) were treated with prostaglandin (PG) and pregnant mares serum gonadotropin (PMSG) or follicle-stimulating hormone (FSH). All animals responded to prostaglandin treatment with shortened cycles and behavioral estrus. Ovulation occurred in all females but only one responded to gonadotrophin treatment with a mild superovulation. An embryo recovered from an Arabian oryx was frozen in liquid nitrogen for 6 months. Upon thawing, the normal-appearing morula was surgically transferred to a scimitar-horned oryx. The recipient failed to carry the embryo and returned to estrus within three weeks of the transfer. It was demonstrated that induction of ovulation and synchronization of estrus can be achieved in the three Oryx species with PMSG or FSH combined with prostaglandin treatment.     

Studies on Asian elephant reproduction at the Washington Park Zoo

Studies of Asian elephant reproduction at the Washington Park Zoo in the areas of the estrous cycle, semen collection, bull elephant management and health care, pregnancy, and pheromones have yielded sufficient information to attempt repeated artificial insemination (AI) at the time of ovulation. While no pregnancy has been achieved to date, with the information now at hand AI can be expected to become a practical technique for breeding elephants in captivity.