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PubMed1974

[Synchronization of estrus in heifers with BOVISYNCHRON].

Heifers were each given 2ml of 1% solution of chlormadinone (CAP, Bovisynchron) for 15 days. Those in group I received one daily dose, while group II received half the dose twice a day. Oestrus was synchronized in all but two heifers. In group II there was a concentrated occurrence of oestrus, so that all heifers could be inseminated on the 5th and 6th days, and earlier inseminations were not needed. This decreased the time required and the number of semen pellets. Results of insemination in two of the three subgroups of group II were 51% in one and 61% in the other, compared with between 32 and 39% in the other subgroup and in group I. Ways of improving the results are discussed.

Administration, Oral↗
PubMed1989

Endocrine, estrous and pregnancy response to varying dosages of Luprostiol in beef cows.

Multiparous lactating beef cows were observed for estrus and randomly assigned to one of four Luprostiol (13, thia-PG-F(2)alpha analog) treatment groups receiving 3.8 (LI), 7.5 (LII), 15 (LIII) or 30 (LIV) mg Luprostiol, respectively, or to an untreated control group (C), or to a positive control group (E) receiving 500 mcg Estrumate. Cows received their respective treatments in a single dosage on Day 7, 8 or 9 of the estrous cycle (estrus = Day 0) and were artificially inseminated 12 h following the subsequent estrus. Blood samples were collected from all groups immediately prior to treatment and at 12-h intervals to 48 h post treatment and analyzed for progesterone (P(4)). Blood samples were collected at 3-h intervals from 24 to 72 h post treatment for animals in Group LIII and for 48 h (or observed estrus) starting on Day 19 of the estrous cycle for animals in Group C. These samples were analyzed for estradiol-17beta(E(2)), follicle stimulating hormone (FSH) and luteinizing hormone (LH). Treatment with Luprostiol at doses >/= 7.5 mg resulted in a synchronous estrous response during the first 5 d post treatment in 75 to 95% of cows treated. Luteal function, as evaluated by systemic P(4) concentration, paralleled results observed for estrous response. Treatment with a 15 or 30 mg dose of Luprostiol resulted in greater overall pregnancy rate at synchronized estrus. No biologically significant differences were found in blood levels of E(2), FSH or LH around the time of estrus between cows in Groups C and LIII. Results from these studies indicate treatment with Luprostiol at doses >/= 7.5 mg resulted in a synchronous estrus during the first 5 d after treatment. Pregnancy rates and endocrine changes were similar to those observed in control and Estrumate-treated cows.

Journal Article↗
PubMed2004

Reinfection with Chlamydophila abortus by uterine and indirect cohort routes reduces fertility in cattle preexposed to Chlamydophila.

This study investigated the effects of controlled reinfection on fertility of cattle naturally preexposed to Chlamydophila abortus. All animals had high prechallenge levels of immunoglobulin M (IgM), IgG, IgG1, and IgG2 serum antibodies against ruminant C. abortus in a chemiluminescent enzyme-linked immunosorbent assay. Twenty virgin heifers were estrus synchronized with prostaglandin F2, artificially inseminated 2 to 3 days later, and challenged immediately by intrauterine administration of 0, 10(4), 10(5), 10(6), or 10(8) inclusion-forming units (IFU) of C. abortus. Ten heifers were estrus synchronized, inseminated, and uterine challenged 2 weeks later. These animals were also indirectly exposed to C. abortus infection (cohort challenged) by contact with their previously challenged cohorts. Pregnancy was determined by rectal palpation 42 days after insemination. All anti-C. abortus antibody isotypes increased in heifers following uterine challenge with 10(8) IFU. A total of 11, 83, 50, 66, and 0% of heifers were pregnant after uterine challenge with 0, 10(4), 10(5), 10(6), and 10(8) IFU of C. abortus, respectively. A total of 50 and 65% of heifers were pregnant with and without cohort challenge, respectively. Uterine inoculum dose and cohort challenge (or, alternatively, a negative pregnancy outcome [infertility]) correlated highly significantly with a rise in postchallenge anti-C. abortus IgM levels over prechallenge levels. Logistic regression modeled fertility, with uterine challenge dose and cohort challenge or prechallenge IgM as predictors (P < 0.05). The models predict that the uterine C. abortus inoculum causing infertility is 8.5-fold higher for heifers without cohort exposure and 17-fold higher for heifers with high IgM levels than for heifers with cohort exposure or with low IgM levels.

Animals↗
PubMed1996

Application of knowledge about corpus luteum function in control of estrus and ovulation in cattle.

Understanding corpus luteum (CL) function has led to development of methods of estrus synchronization in cattle that either extend the estrous cycle by administration of exogenous progestins or shorten the cycle by induction of luteolysis. Both methods have limitations, which have been reduced or overcome through sequential or combined treatment with progestin and luteolytic drugs. Future improvements in estrus synchronization methodology are most likely to come from achieving more synchrony between the development of a highly fertile ovulatory follicle and control of luteal function.

Journal Article↗
PubMed1985

Comparative fertility of normal and repeat-breeding cows as embryo recipients.

Morphologically normal embryos were transferred surgically into uteri of normal and repeat-breeder cows at seven days post-estrus to compare embryo survival rates in the two kinds of cows. All cows were less than ten years of age and had no abnormal genital discharges, cystic ovarian follicles, or anatomical abnormalities of the reproductive tract. Normal cows had not been inseminated after last calving. Repeat-breeders had at least four infertile services within the past six months (average of 6.2 services after calving). To test fertility of repeat-breeders at synchronized estrus, 22 anatomically-normal repeat-breeders were treated by intramuscular (i.m.) injection with prostaglandin F(2)alpha (PGF(2)alpha) on day 11 of an estrous cycle (estrus = day 0) and inseminated at induced estrus; 11 cows (50%) had a normal fetus at necropsy on day 60. Twenty-three repeat-breeders and 23 normal cows were assigned as embryo recipients and treated i.m. with PGF(2)alpha to synchronize estrus. All embryo donors were normal cows. Donors were treated with FSH and PGF(2)alpha and inseminated at estrus. On day 7 after estrus, embryos were recovered nonsurgically from donors and one embryo was transferred through a flank incision to the anterior end of the uterine horn adjacent to the corpus luteum of each recipient. Recipients that did not return to estrus were necropsied at day 60. Of 28 normal and 23 repeat-breeder recipients, 23 normal cows (82%) and 16 repeat breeders (70%) were pregnant at day 60 (P=0.235). Thus, at seven days post-estrus, the maternal environment of most of these repeat-breeders was satisfactory for maintaining pregnancy.

Journal Article↗
PubMed1985

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.

Journal Article↗
PubMed2004

Retrospective analysis of the efficacy of controlled internal drug release in follicular cysts in an embryo donor beef herd.

We investigated the efficacy of a controlled internal drug release (CIDR) device in the reproductive management of an embryo donor beef herd. Superovulation of embryo donors was routinely induced by a combination of FSH and prostaglandin F(2)alpha analogue (PGF(2)alpha) at intervals of a few months, and after embryo recovery estrus of the donors was synchronized with PGF2(2)alpha. Between 1996 and 1998, approximately 20% of donors were diagnosed as having follicular cysts every year. Twenty-eight cases of follicular cysts recorded between 1997 and 1998 were treated with a CIDR device for 14 days to evaluate the efficacy of CIDR in resolving follicular cysts in donor herds. Initial recovery was defined as the occurrence of ovulation with estrous behavior and subsequent formation of a corpus luteum after removal of the CIDR. Initial recovery was recognized in all cases (n=28). Follicular cysts did not recur after repeated embryo recovery in 64% of the initially recovered donors, but in 36% of affected donors cysts recurred after the next embryo recovery. Subsequently, with a CIDR device instead of PGF(2)alpha, we synchronized estrus after embryo recovery in the same herd from 1999 to 2000, to investigate the ability of CIDR to prevent the initiation of follicular cysts. Of the donors used between 1999 and 2000, approximately 30% had a history of follicular cysts. Use of CIDR for estrous synchronization after embryo recovery lowered the incidence of follicular cysts to 3% in 1999 and 0% in 2000. Treatment with CIDR proved effective at resolving follicular cysts in the embryo donor beef herd and enabled re-use of donors affected with follicular cysts. CIDR is also likely to be efficacious in lowering the occurrence of follicular cysts in donor herds when it is used for estrous synchronization after embryo recovery.

Animals↗
PubMed1993

Pregnancy rate is greater when the corpus luteum is present during the period of progestin treatment to synchronize time of estrus in cows and heifers.

Our hypothesis was that conception in bovine females would be enhanced if the corpus luteum was present during the period of progestin treatment to synchronize estrus. In this study, 67 heifers (one replicate) and 124 cows (two replicates) were randomly assigned to one of two treatment groups. Seven days after estrus (Day 0), all animals were implanted with norgestomet and the implant remained in place for 10 days. All implants were removed on Day 17. Cows and heifers in one group received prostaglandin F2 alpha (PGF2 alpha) on Day 7 of the estrous cycle (PG 7; norgestomet without corpus luteum), and animals in the second group received PGF2 alpha on Day 17 (day of implant removal; PG 17; norgestomet with corpus luteum). All heifers and cows exhibiting behavioral estrus were artificially inseminated 12 h after estrus was detected during a 7-day period following removal of norgestomet. Blood samples were collected from cows of replicate 1 to determine serum concentrations of progesterone and 17 beta-estradiol. Percentage of females that had calves as a result of artificial insemination was greater (p < 0.01) in the PG 17 group (87% and 78% cows [two replicates] and 58% heifers) compared to the PG 7 group (31% and 44% cows [two replicates] and 41% heifers).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Relationship between doses of prostaglandin F2alpha and stages of the breeding season for synchronization of estrus and ovulation in ewes.

Two experiments were conducted to compare estrous response to three doses (8, 16 and 24 mg) of prostaglandin F2alpha (PGF2alpha) administered by intramuscular injection to ewes between day 6 and 12 of the estrous cycle (Experiment I) and to ewes on unknown days of the estrous cycle during four different stages of the breeding season (Experiment II). In experiment I, a total of 41 ewes were treated with PGF2alpha. The injection of 24 mg PGF2alpha resulted in a higher proportion of ewes exhibiting estrus (13/14, 92.9%) within 5 days after treatment as compared to the other two doses (2/12 and 10/15, for 8 and 16 mg PGF2alpha, respectively). However, there was no significant difference for the proportion between 16 mg and 24 mg PGF2alpha. In experiment II, PGF2alpha was given to ewes on the 3rd of February (early breeding season), the 28th of February (mid-early breeding season), the 10th of April (mid breeding season) and the 27th of May (late breeding season). These was a significant difference for the proportion of ewes exhibiting estrus between the early breeding season and the other three seasons (P<0.05) but not for ewes ovulating. Throughout the breeding season, 16 mg PGF2alpha appeared to be slightly better than the other two doses (8 and 24 mg) although there was no overall difference in the estrous responses to treatment among the three doses. However, a significant difference in the proportion of ewes ovulating was found among the three doses of PGF2alpha (P<0.05). Especially, 16 mg PGF2alpha was significantly superior to 8 mg (P<0.01) and 24 mg (P<0.05). It was considered that there was a complicated relationship between the doses of PGF2alpha and the stages of the breeding season for induction of estrus and ovulation in the ewe.

Journal Article↗
PubMed1988

Synchronization of estrus in early diestral dairy heifers with Prostaglandin F(2)alpha and estradiol benzoate.

Following observation of estrus, 134 Holstein heifers were given injections of Prostaglandin F(2)alpha (PGF(2)alpha) between Days 5 and 10 of their cycle (estrus = Day 0). They were then randomly assigned to either a group receiving 400 microg of estradiol benzoate (E(2)B) 40 h or maintained as controls. Heifers observed in estrus within 120 h of PGF(2)alpha administration were inseminated (approximately 12 h after initial observation of estrus). Blood samples for progesterone determination were drawn from the coccygeal vein on Days 15 and 21 after insemination. Pregnancy was confirmed by palpation per rectum between Days 5.0 and 60 post insemination. When control and treated heifers were compared it was found that a higher percentage of heifers treated with E(2)B exhibited estrus after PGF(2)alpha, but there had been no effect on subsequent progesterone concentrations or pregnancy rates.

Journal Article↗
PubMed1989

Time of ovulation in the South Australian Merino ewe following synchronization of estrus. 1. Variation within and between flocks.

Observations were made by repeated laparoscopy to determine the time of ovulation in seven flocks of South Australian Merino ewes treated with pregnant mare serum gonadotropin (PMSG, 400 IU per ewe) and an intravaginal pessary containing 60 mg medroxy-progesterone acetate (MAP). Ovulation most often commenced within 57 h of pessary removal and was completed in all flocks within 81 h. There was, however, significant variation in the time of onset of ovulation; it did not commence until 69 h in one of three observations of Flock 1 and in two of three observations of Flock 2. On the other hand, in a flock of two-year-old nulliparous ewes (Flock 7), ovulation commenced significantly (P < 0.001) earlier than in most observations of other flocks, with 18 39 ewes ovulating within 57 h of pessary removal. The effect of the progestagen (MAP vs flugestone acetate) and the gonadotropin preparation (Pregnecol vs Folligon) on the time of ovulation were observed in separate studies. The characteristic time of ovulation was not influenced in either comparison. However, ovulation occurred significantly (P < 0.001) earlier in ewes treated with progesterone released from a controlled internal drug release dispenser (CIDR). The implications of these findings to artificial insemination and embryo transfer are discussed.

Journal Article↗
PubMed1989

Clinical use of Norgestomet ear implants or intravaginal pessaries for synchronization of estrus in anestrous dairy goats.

Ear implants that contained 3 mg Norgestomet or vaginal pessaries that contained 40 or 45 mg fluorogestone acetate were used to induce estrus in dairy goats in three herds in May. Ear implants or vaginal pessaries were left in place for 11 d. Cloprostenol (50 mug) and PMSG (500 IU) were administered i.m. 24 h prior to removal of ear implants or vaginal pessaries. After removal of vaginal pessaries, onset of standing estrus occurred in 22 23 goats (96%) at 20 +/- 4.7 h, in 19 20 goats (95%) at 22 +/- 6.3 h, and in 16 16 goats (100%) at 19 +/- 1.2 h in Herds A, B and C, respectively. After removal of ear implants, onset of standing estrus occurred in 25 25 goats (100%) at 19 +/- 4.9 h, in 20 22 goats (91%) at 22 +/- 7.0 h, and in 15 15 goats (100%) at 18 +/- 2.2 h in Herds A, B and C, respectively. Does were bred by natural service in Herds A and B, and by artificial insemination 28 h after vaginal pessary or ear implant removal in Herd C. Pregnancy rates were determined 39 to 53 d post breeding by real-time ultrasound. Pregnancy rates in goats with vaginal pessaries were 32, 55 and 6%; and in goats with ear implants they were 56, 67 and 27% in Herds A, B and C, respectively. Problems encountered included poor libido in some bucks, abortions in undersized yearling does, and loss of ear implants by three does (not included in the data). Statistically there was no difference in pregnancy rates between goats receiving vaginal pessaries or ear implants (P>0.10).

Journal Article↗
PubMed1993

Increasing exogenous progesterone during synchronization of estrus decreases endogenous 17 beta-estradiol and increases conception in cows.

The objectives of this study were to determine the effects of dose of exogenous progesterone (P4) prior to artificial insemination on concentrations of 17 beta-estradiol (E2) and on conception rates in bovine females. Heifers (n = 100) and cows (n = 100) received P4-releasing intravaginal devices (PRIDs) to produce two different circulating concentrations of P4. All animals received a single PRID 10 days before (Day-10) the start of the breeding season (Day 0). In animals that received the low dose of P4 (1 PRID, target concentration of 2-3 ng/ml of plasma), the original PRID remained in place for 10 days. In animals that received the larger dose of P4 (2 PRIDs, target concentration of 5-8 ng/ml of plasma), an additional PRID was inserted on Day -9. To maintain concentrations of P4 in the 2-PRID group, the PRIDs inserted on Days -10 and -9 were replaced with new PRIDs on Days -5 and -4, respectively. Prostaglandin F2 alpha (25 mg) was administered to all animals on Days -9 and -3 to remove the endogenous source of P4. Following PRID removal, animals were artificially inseminated 12 h after signs of behavioral estrus were observed. A treatment-by-day interaction (p < 0.0001) was observed for concentrations of P4 in circulation of both heifers and cows. Animals that received 2 PRIDs had greater (p < 0.001) concentrations of P4 by Day-8 of treatment than animals that received 1 PRID. In cows that received 1 PRID, concentrations of E2 increased 2.4-fold from Day-10 (6.8 +/- 1.0 pg/ml) to Day-2 (16.7 +/- 1.4 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intravaginal↗