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PubMed1986

Controlling first service and calving interval by prostaglandin F2 alpha, gonadotropin-releasing hormone, and timed insemination.

Our objective was to determine if calving intervals could be shortened and made less variable by using prostaglandin F2 alpha to control the occurrence of first services. Holstein cows (n = 348) were assigned at calving to four treatment groups. Control cows (n = 88) were inseminated at their first observed estrus after 40 d postpartum. Estrous cycles of the remaining cows were synchronized with prostaglandin F2 alpha to allow insemination (first services) 80 h after the second injection (n = 86), insemination at 80 h preceded by gonadotropin-releasing hormone at 72 h (n = 86), or insemination at 72 and 96 h (n = 88) after the second injection (51 to 57 d postpartum). By design, interval to first service was reduced to 57 d for treated cows (63 d for controls) and was less variable (12% of that for controls). Conception rate at first service was lower after timed inseminations than that of controls. Intervals to conception and subsequent calving were similar in all treated cows and controls. Of cows sampled, 23 of 176 (13%) failed to respond with luteolysis when progesterone in serum exceeded 1 ng/ml, and 26 of 176 (15%) had low concentrations of progesterone in serum and could not respond to prostaglandin F2 alpha. Poor response to timed inseminations may have occurred because only 72% of 176 cows sampled responded with luteolysis. When only cows observed in estrus were considered, conception rate approached that of controls (51%).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1985

Ovulation rate in sheep selected for weaning weight or litter size.

Ovulation rate was measured by laparoscopy at two consecutive cycles on 366 ewes 2 yr old and over and 85 yearling ewes of five lines of Targhees from the base base population; 53 yearling linecross ewes were also included. The lines were two unselected controls (HCl and DC), two selected for 21 yr for increased 120-d weight (HW and DH) and one selected for 19 yr for multiple births (T). Ewes were synchronized in late July or early August at the start of the normal breeding season with intravaginal pessaries impregnated with 60 mg methylacetoxyprogesterone and examined at first and second estrus. Ovulation had occurred in both cycles in 327 (89%) and 177 (85%) of the mature and yearling ewes, respectively. Overall mean numbers of corpora lutea at first and second estrus were 1.42 and 1.63, respectively for ewes 2 yr and over and 1.20 and 1.44 for yearlings, indicating an effect of synchronizing treatment, season, flushing, or a combination of these. Among mature ewes, ovulation rate was higher (P less than .05) in DH (+.20), HW (+.19) and T (+.16) than in controls at first estrus, and in HW (+.29) and T (+.21) but not DH (-.04) at second estrus. Among yearlings, differences were significant only at second estrus (HW, +.40; T, +.35) and again not for DH (+.08). The failure of line DH to increase in ovulation rate from first to second estrus as did other lines was transmitted to linecross progeny. Body weight within line affected ovulation rate significantly, with a greater effect at second estrus, in both age groups. Adjustment for body weight removed the difference between HW and controls but not between T and controls. Repeatability of corpora lutea count was .27 and .25 for mature and yearling ewes, respectively.

Animals↗
PubMed1988

Co-culture of ovine eggs with oviductal cells and trophoblastic vesicles.

Three experiments were conducted to determine whether coculture of early sheep eggs with oviductal cells would improve the ability of eggs to survive in culture. Eggs recovered from superovulated ewes were cultured in Ham's F-10 medium supplemented with 10% fetal calf serum (F10FCS) at 37.5 degrees C in 95% air:5% CO(2). In Experiment 1, eggs with one to eight cells were either transferred into recipient ewes immediately after collection or were cultured for 24 h in 5 ml Ham's F10 medium supplemented with 10% fetal calf serum (F10FCS), 5 ml F10FCS on a confluent monolayer of oviductal cells; in 25 ml of fresh F10FCS; or in 25 ml of F10FCS removed cultures of oviductal cells, 25 mul of fresh F10FCS or 25 mul of F10FCS removed from cultures of oviductal cells. After 24 h, the cultured eggs were transferred to recipient ewes synchronous with donors and subsequently recovered at necropsy on Day 8 post estrus. Coculture of sheep eggs with oviductal cells improved (P < 0.05) the development of transferred eggs compared to culture in F10FCS alone. In Experiment 2, eggs recovered from superovulated ewes on Days 3 to 6 after estrus had undergone 1.8 cleavages by Day 3 and 4.1 cleavages by Day 6. In Experiment 3, single-cell eggs were cultured for 3 d in 5 ml F10FCS, cocultured with ovine trophoblastic vesicles or cultured on a confluent monolayer of oviductal cells. Coculture of eggs in F10FCS on a monolayer of oviductal cells supported in vitro egg cleavage to a greater degree than did F10FCS alone or F10FCS with trophoblastic vesicles (P < 0.05). In Experiment 4, single-cell eggs were cultured for 3 d then transferred to recipients. Eggs were cultured in 5 ml F10FCS on confluent monolayers of oviductal cells from luteal or estrous ewes or on cells that had been frozen after recovery from a culture of oviductal cells. After culture, the eggs were transferred to oviducts of recipients and recovered 3 d later at necropsy. Coculture of eggs for 72 h with oviductal cell monolayers did not increase the in vitro, or subsequent in vivo, cleavage rate regardless of the type of oviductal cells.

Journal Article↗
PubMed1996

In vitro development of embryos from superovulated gilts treated with the progesterone agonist, altrenogest (Regu-Mate) or the prostaglandin analogue, cloprostenol (Planate).

This study was conducted to compare the in vitro development of embryos from superovulated postpubertal gilts synchronized with progesterone agonist altrenogest (REG, Regu-Mate) and those from superovulated prepubertal gilts synchronized with prostaglandin analogue cloprostenol (PLA, Planate). Ten postpubertal gilts that had exhibited estrus at least once were fed 20 mg/d of REG from Day 0 (the first day of treatment, may have been any day of the estrous cycle) to Day 17. The gilts received intramuscularly (im) 1500 IU of equine chorionic gonadotropin (eCG) on the afternoon of Day 17, followed by 1000 IU of human chorionic gonadotropin (hCG) 84 h later. Eight prepubertal gilts received intramuscularly one dose of a combination of 400 IU of eCG and 200 IU of hCG (PG 600) on Day 0 (the first day of treatment), followed by 750 IU of hCG on Day 3. From Day 16 to Day 19, the prepubertal gilts received 350 mg/d of PLA, followed by 1500 IU of eCG on the afternoon of Day 19, then 1000 IU of hCG 84 h later. Gilts were checked for estrus with an intact boar. At estrus, all gilts were artificially inseminated and/or mated twice at 12-h intervals. Then 50 to 54 h after the hCG injection, a mid-ventral laparotomy was performed on each gilt. Corpora albicans (CA) and corpora hemorrhagica (CH) were counted, and oviducts were flushed in situ. The embryos recovered (1- to 2-cell) were cultured in modified Whitten's medium at 38.5 degrees C under an atmosphere of 5% CO2 in air for 144 h. The number of CA per gilt did not differ between the postpubertal and prepubertal gilts (11.9 vs 7.9, respectively; P > 0.05). However, the number of CH per gilt (27.5 vs 18.1, P = 0.05) and the number of embryos per gilt (26.2 vs 15.3, P < 0.05) were higher in postpubertal gilts than in prepubertal gilts. Furthermore, after 144 h of in vitro culture, the percentage of embryos cleaving to the >-16-cell (morula + blastocysts) or > or =32-cell (blastocysts) was greater (P < 0.05) in prepubertal gilts than in postpubertal gilts (85.2 vs 68.5, 55.7 vs 44.2, respectively). The total numbers of embryos examined were 122 and 260 in prepubertal and postpubertal gilts, respectively. These results show that postpubertal gilts treated with REG produced a higher number of embryos. However, better embryo development was noted with zygotes from prepubertal gilts primed with exogenous gonadotrophin, followed by synchronization with prostaglandin before induction of superovulation and insemination.

Journal Article↗
PubMed2001

Effect of excess degradable intake protein on early embryonic development, ovarian steroids, and blood urea nitrogen on days 2, 3, 4, and 5 of the estrous cycle in mature ewes.

Two trials were conducted to determine whether feeding excess degradable intake protein (DIP) during a synchronized estrous cycle and the first 5 d after breeding alters early embryonic development, ovarian steroids, or BUN concentrations in ewes. Ewes were group-fed in Trial 1 (T1) and individually fed in Trial 2 (T2) either 100 (control; T1, n = 15; T2, n = 12) or 200% (high-protein; T1, n = 16; T2, n = 12) of the NRC protein recommendation for maintenance during a synchronized estrous cycle until surgery in the next cycle. Ampullae (AMP), isthmi (IST), and uterine horns (UT) of high-protein and control ewes were removed on d 2 (T1), 3 (T2), 4 (T1), or 5 (T2) after breeding. In T1, jugular blood samples were taken once daily starting on d 2 of the synchronized cycle, and in T2 on d 2, 9, 15, 16, and 17, and in both trials from estrus (d 0) to the day of surgery. Ampullae, IST, and UT flushings were examined microscopically for the presence of embryos, embryo condition, and embryo cell number. There was no trial x treatment interaction (P > or = 0.10), so data for both trials were pooled. Concentrations of BUN were higher (P < 0.05) in high-protein-fed ewes than in control ewes during the synchronized cycle and the first 5 d of the next cycle. Progesterone concentrations of the synchronized cycle did not differ (P > 0.10) between treatments. During the first 5 d of the next cycle, estradiol-17beta concentrations were lower (P = 0.06) in high-protein-fed than in control ewes. Progesterone increased (P < 0.05) to higher concentrations by d 5 in high-protein-fed ewes than in control ewes. More (P < 0.05) embryos were found in AMP of high-protein-fed ewes than in AMP of control ewes on d 4. Fewer (P = 0.05) embryos were found in UT of high-protein-fed ewes than in UT of control ewes on d 4. More embryos were found in UT of high-protein-fed ewes than in UT of control ewes on d 5. Fewer (P = 0.05) embryos were found in IST of high-protein ewes than in the IST of control ewes on d 5. Embryos of high-protein-fed ewes had more (P < 0.05) cells than embryos from control fed ewes on d 5. Feeding ewes excess DIP protein during an estrous cycle and the first 5 d after breeding initially impeded embryo transport; thereafter, embryo transport and development through the oviduct was accelerated.

Animals↗
PubMed1991

Transfer of porcine embryos after 3 days of in vitro culture.

Two experiments were conducted to determine the viability of porcine embryos transferred after long-term in vitro culture. In Exp. 1, four-cell embryos were kept in culture for 120 h. Embryos that were exposed to fresh culture medium every 12 h survived better than embryos kept in the same medium throughout the culture period. In Exp. 2, four- and eight-cell embryos were cultured in vitro for 72 h before transfer to estrus-induced recipient gilts. Each gilt received, on average, 19 embryos. If recipients were synchronous with donors 3/32 (9%) recipients remained pregnant with an average of 4.0 +/- .6 viable young. If the sexual cycle of the recipients was 24 h behind that of the donors the pregnancy rate was 18/34 (53%) with 4.4 +/- .5 viable young. Average embryo survival rate for the two groups was 1.8 and 12.5%, respectively. A 24-hourly medium replacement during the in vitro culture period had no significant effect on transfer results. When transferring freshly collected blastocysts, pregnancy rate, number of viable young and survival rate of embryos were 6/10 (60%), 7.8 +/- 1.4, and 23.9% for synchronous recipients and 7/10 (70%), 9.3 +/- 1.8, and 32.9% for asynchronous recipients, respectively. Recipients with very high plasma progesterone levels or numerous follicular cysts at the time of transfer were less likely to remain pregnant than others.

Animals↗
PubMed2005

Superovulation and embryo transfer in Bos indicus cattle.

Compared to Bos taurus breeds, Bos indicus breeds of cattle present several differences in reproductive physiology. Follicular diameter at deviation and at the time of ovulatory capability are smaller in B. indicus breeds. Furthermore, B. indicus breeds have a greater sensitivity to gonadotropins, a shorter duration of estrus, and more often express estrus during the night. These differences must be considered when setting up embryo transfer programs for B. indicus cattle. In recent studies, we evaluated follicular dynamics and superovulatory responses in B. indicus donors with the objective of implementing fixed-time AI protocols in superstimulated donors. Protocols using estradiol and progesterone/progestrogen releasing devices to control follicular wave emergence were as efficacious as in B. taurus cattle, allowing the initiation of superstimulatory treatments (with lower dosages of FSH than in B. taurus donors) at a self-appointed time. Furthermore, results presented herein indicate that delaying the removal of progesterone/progestogen-releasing devices, combined with the administration of GnRH or pLH 12 h after the last FSH injection, results in synchronous ovulations, permitting the application of fixed-time AI of donors without the necessity of estrus detection and without compromising the results.

Animals↗
PubMed1990

Syncro-mate B induces estrus in ovariectomized cows and heifers.

Eleven ovariectomized Hereford x Simmental cows and 10 ovariectomized crossbred heifers (primarily Angus and Hereford) were given the Syncro-Mate B (SMB) estrous synchronization treatment. The SMB treatment consisted of a 2 ml i.m. injection containing 5 mg of estradiol valerate and 3 mg of norgestomet plus a hydron ear implant containing 6 mg of norgestomet. The ear implant was removed 9 d later. Cows and heifers were considered in estrus only if they stood for mounting by a herdmate or a bull. Observations for estrus were made four or six times each day for 3 d after implant removal. The 21 animals were used in eight trials. Each trial involved 9 or 11 cows or 5 or 10 heifers. Four days to three weeks elapsed between implant removal and implant insertion for the next trial. No ovariectomized cow or heifer was observed in estrus for 21 d before treatment with SMB. In the eight trials, 3 of 9, 7 of 9 and 6 of 11 cows exhibited estrus, whereas 5 of 10, 1 of 5, 3 of 5, 3 of 5 and 5 of 5 heifers exhibited estrus after treatment. When data were pooled, 16 of 29 (55.2%) cows and 17 of 30 (56.7%) heifers exhibited estrus after treatment. Our data indicate that the SMB treatment can induce estrus in cows and heifers, independently of the ovaries.

Journal Article↗
PubMed1990

Intrauterine insemination of farmed fallow deer (Dama dama) with frozen-thawed semen via laparoscopy.

Estrus and ovulation of mature fallow does (n=155) on two North American farms were synchronized by intravaginal silastic devices containing 0.3 g progesterone (CIDR-type G) for 14 d. Each of 151 does received laparoscopic intrauterine inseminations of either 50x10(6) (n=125) or 25x10(6) (n=26) frozen-thawed spermatozoa, 65 to 68 h after CIDR device withdrawal. Four does received intrauterine inseminations per vaginam of 50x10(6) spermatozoa 68 to 69 hours after CIDR device withdrawal. Semen from crossbred Dama dama damaxDama dama mesopotamica sires was collected in New Zealand by electroejaculation. The overall pregnancy rate to artificial insemination, as assessed by rectal ultrasonography at Day 45, was 67.7%. The pregnancy rates for does receiving laparoscopic inseminations were 58.2% (Texas; 50x10(6) spermatozoa; n=79 does); 80.8% (Texas; 25x10(6) spermatozoa; n=26 does) and 76.1% (New York; 50x10(6) spermatozoa; n=46 does). Three of the four does receiving intrauterine inseminations per vaginam became pregnant to the frozen-thawed semen.

Journal Article↗
PubMed1992

Endocrine and ovarian responses associated with the first-wave dominant follicle in cattle.

To examine endocrine and biochemical differences between dominant and subordinate follicles and how the dominant follicle affects the hypothalamic-pituitary-ovarian axis in Holstein cows, the ovary bearing the dominant follicle was unilaterally removed on Day 5 (n = 8), 8 (n = 8), or 12 (n = 8) of synchronized estrous cycles. Follicular development was followed daily by ultrasonography from the day of detected estrus (Day 0) until 5 days after ovariectomy. Aromatase activity and steroid concentrations in first-wave dominant and subordinate follicles were measured. Intact dominant and subordinate follicles were cultured in 4 ml Minimum Essential Medium supplemented with 100 microCi 3H-leucine to evaluate de novo protein synthesis. Five days after unilateral ovariectomy, cows were resynchronized and the experiment was repeated. Follicular growth was characterized by the development of single large dominant follicles, which was associated with suppression of other follicles. Concentrations of estradiol-17 beta (E2) in follicular fluid and aromatase activity of follicular walls were higher in dominant follicles (438.9 +/- 45.5 ng/ml; 875.4 +/- 68.2 pg E2/follicle) compared to subordinate follicles (40.6 +/- 69.4 ng/ml; 99.4 +/- 104.2 pg E2/follicle). Aromatase activity in first-wave dominant follicles was higher at Days 5 (1147.1 +/- 118.1 pg E2/follicle) and 8 (1028.2 +/- 118.1 pg E2/follicle) compared to Day 12 (450.7 +/- 118.1 pg E2/follicle). Concentrations of E2 and androstenedione in first-wave dominant follicles were higher at Day 5 (983.2 +/- 78.2 and 89.5 +/- 15.7 ng/ml) compared to Days 8 (225.1 +/- 78.6 and 5.9 +/- 14.8 ng/ml) and 12 (108.5 +/- 78.6 and 13.0 +/- 14.8 ng/ml). Concentrations of progesterone in subordinate follicles increased linearly between Days 5 and 12 of the estrous cycle. Plasma concentrations of FSH increased from 17.9 +/- 1.4 to 32.5 +/- 1.4 ng/ml between 0 and 32 h following unilateral removal of the ovary with the first-wave dominant follicle. Increases in plasma FSH were associated with increased numbers of class 1 (3-4 mm) follicles in cows that were ovariectomized at Day 5 or 8 of the cycle. Unilateral ovariectomy had no effects on plasma concentrations of LH when a CL was present on the remaining ovary. First-wave dominant follicles incorporated more 3H-leucine into macromolecules and secreted high (90,000-120,000) and low (20,000-23,000) molecular weight proteins that were not as evident for subordinate follicles at Days 8 and 12.(ABSTRACT TRUNCATED AT 400 WORDS)

Androstenedione↗