THE INFLUENCE OF GONADOTROPHIN-RELEASING HORMONE AT ESTRUS ON OVULATION RATE AND THE DEVELOPMENT OF CORPORA LUTEA IN EWES

1990 ◽  
Vol 70 (3) ◽  
pp. 983-985 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
L. M. RUTTER ◽  
F. X. AHERNE
Keyword(s):  
Key Words ◽  
Binding Capacity ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

Twenty-two ewes received either 30 μg GnRH or saline at the onset of estrus. Blood samples were obtained on days 1–7 (day 0 = estrus) and corpora lutea recovered surgically at day 7. There was no effect of GnRH on the number or weight of corpora lutea nor on the concentrations of progesterone in either corpora lutea or plasma. GnRH treatment caused an increase (P < 0.07) in luteal hCG binding capacity (0.66 ± 0.12 vs. 0.34 ± 0.12 nmol mg−1 protein). Key words: GnRH, estrus, corpora lutea, hCG binding

160 Increasing gonadotrophin-releasing hormone dose at initiation of a 5-day CO-Synch protocol increases ovulatory response but not fertility in yearling beef heifers

2020 ◽  
Vol 32 (2) ◽  
pp. 206
Author(s):  
E. Rojas Canadas ◽  
S. E. Battista ◽  
J. Kieffer ◽  
S. Wellert ◽  
A. Garcia Guerra
Keyword(s):  
Dose Group ◽  
Fixed Time ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Double Dose ◽  
Device Removal ◽  
Beef Heifers ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
To Receive

Heifers typically have a reduced ovulation rate following gonadotrophin-releasing hormone (GnRH) application at initiation of a CO-Synch + controlled internal drug release (CIDR) protocol. Thus, the objective of the present study was to determine whether increasing the dose of GnRH at initiation of a 5-day CO-Synch protocol in beef heifers would improve ovulation rate and therefore increase pregnancies per AI (P/AI). Angus yearling heifers (n=299) at five locations in Ohio (United States) were randomised to receive either 100µg (single; n=149) or 200µg (double; n=150) of gonadorelin acetate (Gonabreed, Parnell) at initiation of a 5-day CO-Synch. On Day −8, heifers received a new intravaginal progesterone-releasing device (1.38g of progesterone; CIDR, Zoetis) and either a single or double dose of GnRH as described above. Five days later (Day −3), devices were removed, 1000µg of cloprostenol sodium (Estroplan, Parnell) was administered, and an oestrous detection patch was applied (Estrotect, Rockway Inc.). Sixty hours after device removal, AI was performed concurrently with the administration of 100µg of GnRH. Pregnancy was determined using ultrasonography 35 days after AI. Ovaries from a subset of animals (n=178) were examined on Days −8 and −3 using ultrasonography to determine the presence of corpora lutea (CL) and the size of the largest follicle. Data were analysed using the GLIMMIX procedure of SAS ver. 9.4 (SAS Institute Inc.). Oestrous expression was similar (P=0.50) between heifers treated with a single (49.0%) or double (52.7%) dose of GnRH. Overall, P/AI was similar (P=0.35) between heifers receiving a single (43.6%; 65/149) or double (38.7%; 58/150) dose of GnRH at initiation of the protocol. However, increasing the dose of GnRH resulted in a greater (P=0.04) ovulation rate in heifers in the double-dose group (40.9%; 36/88) compared with those in the single-dose group (26.1%; 23/88). In addition, heifers with a CL at the time of treatment had reduced ovulatory response to GnRH treatment (16.0%) compared with heifers without a CL (53.7%; P=0.001); however, there was no treatment×CL presence interaction (P=0.69). Heifers that did not ovulate to the initial GnRH treatment had a greater (P=0.0008) diameter of the largest follicle on Day −3 compared with heifers that did ovulate (11.4±0.2 vs. 10.0±0.3). Furthermore, heifers that did ovulate after the initial GnRH had greater (P=0.04) P/AI (52.5%) than heifers that did not ovulate (40.2%), and heifers with a CL on Day −8 tended (P=0.07) to have greater P/AI (47.9%) than heifers without a CL (40.2%). In addition, heifers with a CL present on Day −3 had greater (P=0.04) P/AI (48.2%) than heifers without a CL (31.7%). In summary, increasing the dose of GnRH at initiation of a 5-day CO-Synch did not affect fertility to fixed-time AI but enhanced ovulation rate in beef heifers. Furthermore, heifers that did ovulate at initiation of the protocol or that had a CL at device insertion or removal had greater fertility to fixed-time AI. Thus, alternative strategies that maximise ovulation at initiation of the synchronisation protocol are needed.

Effect of lupin (Lupinus angustifolius) supplementation on ovarian and pituitary activity in ewes

1991 ◽  
Vol 3 (1) ◽  
pp. 109 ◽  
Author(s):  
BH Pearse ◽  
NP McMeniman ◽  
KF Dowsett
Keyword(s):  
Direct Effect ◽  
Anterior Pituitary ◽  
Follicle Stimulating Hormone ◽  
Nutrient Status ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Pregnant Mare Serum Gonadotrophin ◽  
Maintenance Ration

In each of three experiments, thirty seasonally anoestrous Border Leicester ewes were fed on a maintenance ration of oaten chaff. Fifteen of them were given a supplement of 500 g lupin grain per head per day. The ewes were treated with 10 mg follicle stimulating hormone (Expt 1), 600 I.U. pregnant mare serum gonadotrophin (Expt 2) and either 150 or 300 micrograms gonadotrophin releasing hormone (Expt 3) to determine whether the ovaries and/or the anterior pituitary were capable of responding to the nutrient status of the animals and influencing ovulation rate. In each experiment, the number and size of corpora lutea and follicles in the lupin-supplemented and -unsupplemented groups were similar. It was concluded that the mechanism by which lupins increase the ovulation rate is probably neural and not a result of direct effect on either the pituitary or the ovaries.

THE INFLUENCE OF EXOGENOUS GROWTH HORMONE ON OVULATION RATE IN GILTS

1988 ◽  
Vol 68 (4) ◽  
pp. 1097-1103 ◽  
Author(s):  
R. N. KIRKWOOD ◽  
P. A. THACKER ◽  
A. D. GOONERATNE ◽  
B. L. GUEDO ◽  
B. LAARVELD
Keyword(s):  
Growth Hormone ◽  
Crude Protein ◽  
Ovulation Rate ◽  
Daily Injection ◽  
Corpora Lutea ◽  
Blood Samples ◽  
High Incidence ◽  
Exogenous Growth ◽  
Ad Libitum

A total of 32 prepubertal gilts of Yorkshire and Landrace breeding were selected at 138 d and fed ad libitum a 16.2% crude protein diet formulated to provide 13.1 MJ DE kg−1. From selection until the end of second estrus, the gilts were exposed to a boar for 30 min d−1 to facilitate the detection of pubertal and second estrous periods. From 14 d after puberty, the gilts received daily injections of either porcine growth hormone at 90 μg kg−1 body weight (GH; n = 20) or vehicle (CT; n = 12) until 24 h after the onset of second estrus and were then killed 9 d later to determine ovulation rate. Gilts not displaying a second estrus by 24 day after puberty were considered anestrus and the injection regime was halted. Anestrous gilts were killed 30–32 d after puberty and their ovaries examined for the presence of corpora albicantia and the absence of corpora lutea. Blood samples were obtained from all gilts at 14, 17, and 20 d after puberty. There was no treatment effect on the duration of the estrous cycle (20.8 vs. 21.3 d for GH and CT, respectively), but while all CT gilts cycled normally, only 55% of the GH gilts had a second estrus (P < 0.01). In those gilts having a second estrus, the daily injection of growth hormone increased ovulation rate (14.3 vs. 12.4 for GH and CT respectively; P < 0.03). Serum type 1 insulin-like growth factor (IGF-1) concentrations were higher (P < 0.001) in GH than in CT gilts, but there was no difference between cycling and anestrous GH gilts. We suggest that the effect of growth hormone on ovulation rate was mediated by increased secretion of IGF-1. The etiology of the high incidence of anestrus is, however, not known. Key words: Gilts, growth hormone, ovulation rate

Vaccination against follistatin and the effect on ovulation rate in estrus-induced gilts

2003 ◽  
Vol 83 (3) ◽  
pp. 487-492
Author(s):  
C. R. Christensen ◽  
M. J. Redmond ◽  
B. Laarveld
Keyword(s):  
Treatment Group ◽  
Key Words ◽  
Luteal Phase ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Significant Difference ◽  
Ovarian Morphology ◽  
Antibody Titers

Primiparous sows were vaccinated against follistatin to determine the effect on ovulation rate following typical commercial estrus induction and synchronization. Seventy-five gilts received four vaccinations against a recombinant porcine follistatin (FS) or a sham vaccine (CTL). At 85 kg, gilts were induced into estrus with a combination of PG600 and hCG and synchronized using PGF2α. At the second estrus, antibody titers ranged from 0 to1:6400 in the FS-vaccinated treatment group and no FS antibodies were detected in the CTL group. Late in the second subsequent luteal phase the reproductive tracts of the gilts that had displayed two estruses were collected. There was no significant difference in the number of corpora lutea (FS = 13.2 ± 0.5, CTL = 14.5 ± 0.7) or corpora albicantia (FS = 12.1 ± 1.9, CTL = 12.3 ± 2.0) between treatments. Follistatin-vaccinated gilts displayed an increased number of luteal structures which resembled corpora hemorrhagica (P = 0.04). This study shows that vaccination of gilts against FS concurrent with estrus induction and synchronization affected ovarian morphology, although an effect on ovulation rate was not apparent. Key words: Swine, follistatin, immunoneutralization, fecundity, ovulation rate

The effect of a potent gonadotrophin-releasing hormone antagonist on ovarian secretion of oestradiol, inhibin and androstenedione and the concentration of LH and FSH during the follicular phase of the sheep oestrous cycle

1990 ◽  
Vol 126 (3) ◽  
pp. 377-384 ◽  
Author(s):  
B. K. Campbell ◽  
A. S. McNeilly ◽  
H. M. Picton ◽  
D. T. Baird
Keyword(s):  
Gnrh Antagonist ◽  
Venous Blood ◽  
Hormone Secretion ◽  
Experimental Period ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Inhibitory Feedback ◽  
Gonadotrophin Releasing Hormone

ABSTRACT By selective removal and replacement of LH stimulation we sought to examine the relative importance of inhibin and oestradiol in controlling FSH secretion, and the role of LH in the control of ovarian hormone secretion, during the follicular phase of the oestrous cycle. Eight Finn–Merino ewes which had one ovary removed and the other autotransplanted to a site in the neck were given two injections of a gonadotrophin-releasing hormone (GnRH) antagonist (50 μg/kg s.c.) in the follicular phase of the cycle 27 h and 51 h after luteal regression had been induced by cloprostenol (100 μg i.m.). Four of the ewes received, in addition, i.v. injections of 2·5 μg LH at hourly intervals for 23 h from 42 to 65 h after GnRH antagonist treatment. Ovarian jugular venous blood samples were taken at 10-min intervals for 3 h before and 5 h after the injection of antagonist (24–32 h after cloprostenol) and from 49 to 53 h after antagonist (74–78 h after cloprostenol). Additional blood samples were taken at 4-h intervals between the periods of intensive blood sampling. The GnRH antagonist completely inhibited endogenous pulsatile LH secretion within 1 h of injection. This resulted in a marked decrease in the ovarian secretion of oestradiol and androstenedione (P<0·001), an effect that was reversible by injection of exogenous pulses of LH (P<0·001). The pattern of ovarian inhibin secretion was episodic, but removal or replacement of stimulation by LH had no effect on the pattern or level of inhibin secretion. Peripheral concentrations of FSH rose (P<0·01) within 20 h of administration of the antagonist and these increased levels were maintained in ewes given no exogenous LH. In ewes given LH, however, FSH levels declined within 4 h of the first LH injection and by the end of the experimental period the levels of FSH were similar to those before administration of antagonist (P<0·01). These results confirm that ovarian oestradiol and androstenedione secretion, but not inhibin secretion, is under the acute control of LH. We conclude that oestradiol, and not inhibin, is the major component of the inhibitory feedback loop controlling the pattern of FSH secretion during the follicular phase of the oestrous cycle in ewes. Journal of Endocrinology (1990) 126, 377–384

THE BREEDING SEASON AND OVULATION RATE OF DLS EWES AS DETERMINED BY LAPAROSCOPY

1986 ◽  
Vol 66 (1) ◽  
pp. 297-301 ◽  
Author(s):  
MOHAMED H. FAHMY ◽  
JACQUES J. DUFOUR
Keyword(s):  
Key Words ◽  
Breeding Season ◽  
Ovulation Rate ◽  
Corpora Lutea

Ovaries of 19 DLS (1/2 Dorset 1/4 Leicester 1/4 Suffolk) ewes were examined by laparoscopy at 16- to 18-day intervals to determine the length of the breeding season. Nine ewes (47%) had corpora lutea (CL) and/or corpora albicantia (CA) between 22 Apr. and 26 May 1983. The average date of the first estrus accompanied by mounting was 28 Aug. ± 10 d in 1983 and 20 Sept. ± 15 d in 1984. The interval between first and last observed CL and first and last mounting averaged 251 ± 28, and 222 ± 32 d, respectively. The average dates in 1984 when mounting ceased and CL and CA were last observed were 11 Apr. ± 26 d, 26 Apr. ± 27 d and 9 May ± 30 d, respectively. The anestrous period averaged 133 ± 28 d. The average ovulation rate at the last two cycles of a season and the first two cycles of the following breeding season were 1.6 ± 0.53 and 1.7 ± 0.65 for the 1983 and 1.1 ± 0.31 and 1.4 ± 0.71 for the 1984 seasons, respectively. Key words: Breeding season, ovulation rate, laparoscopy, DLS sheep

Gonadotrophin releasing hormone receptors and the response of pituitary gonadotrophs in culture

1983 ◽  
Vol 98 (3) ◽  
pp. 391-399 ◽  
Author(s):  
A. Bérault ◽  
M.-T. Jansem de Almeida Catanho ◽  
M. Théoleyre ◽  
M. Jutisz
Keyword(s):  
Hormone Receptors ◽  
Binding Capacity ◽  
High Capacity ◽  
Biological Response ◽  
Cell Number ◽  
Culture Period ◽  
Pituitary Cells ◽  
Cell Content ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

We have investigated the effect of the time of culture on cell number, cell content of LH, cell responsiveness to gonadotrophin releasing hormone (GnRH) and binding parameters of GnRH in rat anterior pituitary cells in culture. Although a decrease in the cell number was observed during the culture period, the cell content of LH remained unchanged. The receptor affinity (Ka) in acutely dispersed cells was 0·86 × 107l/mol for [3H]GnRH and 1·36 × 1010l/mol for a highly potent agonist, d-Ser(But)6]GnRH(1–9)nonapeptide-ethylamide (GnRH-A). The affinity and binding capacity (0·3 fmol/106 cells) for iodinated GnRH-A did not change significantly during the 6-day culture period. On the contrary, the values of Ka and binding capacity (257 fmol/106 cells) for tritiated GnRH decreased by about 50% betweeen days 1 and 6 of culture. Our results suggest that 125I-labelled GnRH-A binds mostly to high-affinity and low-capacity receptor sites, while [3H]GnRH, which must be used at a higher concentration, also binds to low-affinity, high-capacity binding sites and is therefore useless for the measurement of GnRH receptor binding affinity and binding capacity. Since the biological response of the cells to GnRH increased with the time of culture, it is concluded that although GnRH action is receptor-mediated, binding capacity and biological activity are not necessarily correlated.

83 Response to follicle-stimulating hormone superstimulation in heifers with ovarian activity suppressed by active immunization against gonadotrophin-releasing hormone

2021 ◽  
Vol 33 (2) ◽  
pp. 149
Author(s):  
N. E. S. Pereira ◽  
L. P. Martins ◽  
R. M. Moura ◽  
L. R. O. Dias ◽  
M. A. S. Peixer ◽  
...  
Keyword(s):  
Active Immunization ◽  
Repeated Measure ◽  
Ovarian Activity ◽  
Corpora Lutea ◽  
Follicle Growth ◽  
Releasing Hormone ◽  
Significant Difference ◽  
Follicle Size ◽  
Gonadotrophin Releasing Hormone ◽  
Group B

In the present study, we evaluated the ovarian response to exogenous FSH stimulation in the absence of endogenous LH, using as experimental model heifers immunized against GnRH. Pubertal, cycling Nelore (Bos indicus) heifers were allocated into three experimental groups: (1) non-immunized, FSH stimulated (B−FSH+, n=5), (2) immunized, FSH stimulated (B+FSH+, n=5), and (3) immunized, nonstimulated (B+FSH−, n=5). Active immunization was obtained by 3 subcutaneous injections of 1.0mL anti-gonadotrophin-releasing hormone vaccine (Bopriva, Zoetis), given at 20-day intervals. Effective immunization was characterised by the absence of growing follicles &gt;4mm or corpora lutea (CL) on the ovaries. Follicular wave emergence was synchronized in groups B+FSH+ and B+FSH− by follicle ablation, and in group B−FSH+ by using of a protocol consisting of an injection of 2mg of oestradiol benzoate and 0.5mg of sodium cloprostenol, and insertion of an intravaginal progesterone (P4) device (1g). Four days later (Day 0), groups B−FSH+ and B+FSH+ received 100mg of NIH-FSH-P1 (Folltropin-V, Vetoquinol), injected twice-a-day in 8 decreasing doses, and group B+FSH− received saline. Transvaginal ultrasonography (7.5MHz) was performed daily from Days 0 to 4 and the number and size of follicles were recorded. P4 devices of group B-FSH+ were removed at Day 3. All heifers underwent ovum pickup (OPU) at Day 4, and the cumulus–oocyte complexes (COC) recovered were graded for quality. Viable COC were used for invitro embryo production. The heifers were re-evaluated at Day 11 (7 days after OPU). The GLIMMIX procedure from SAS (SAS Institute Inc.) with repeated-measure statement was used to analyse the effects of group, day, and interactions; and the Chi-squared method was used to analyse binomial data. The results are shown as mean±s.e.m. A progressive increase in average follicle size was observed in groups B−FSH+ and B+FSH+ (P&lt;0.0001), whereas no follicle growth was observed in group B+FSH− (P&gt;0.05). Follicle growth rate was similar between groups B−FSH+ and B+FSH+, and both were greater than group B+FSH− (1.2±0.2 and 1.1±0.1 vs. 0.0±0.1 mm/d; P&lt;0.0001). However, the smaller follicle size in group B+FSH+ at Day 0 resulted in smaller follicle size at Day 4, compared with group B−FSH+ (2.4±0.1 vs. 3.6±0.2 and 6.9±0.7 vs. 8.2±0.6mm, respectively; P&lt;0.05). There was no (P&gt;0.05) difference in the number of COC recovered among groups. The group B+FSH+ yielded fewer (P&lt;0.01) COC of grades I and II and more (P&lt;0.01) degenerated oocytes than groups B−FSH+ and B+FSH− (41.2% vs. 80.0% and 68.0%, and 34.0% vs. 19.8 and 7.0%, respectively). Nevertheless, blastocyst rates were similar (P&gt;0.05) for B−FSH+, B+FSH+, and B+FSH− (57.1%, 45.9% and 44.2%, respectively). Residual follicles or luteal tissue were observed after OPU only in group B−FSH+, resulting in a significant difference in the size of ovaries between Days 0 and 11, compared with that of groups B+FSH+ and B+FSH− (3.7±1.4 vs. 0.2±0.2 and −0.2±0.2cm2, respectively; P&lt;0.05). In summary, exogenous FSH supported follicle growth but did not improve oocyte quality in heifers immunized against GnRH. This research was funded by CAPES.

Prepubertal reduction of the ovarian follicle population by combined LH-releasing hormone antagonist treatment and unilateral ovariectomy influences follicle characteristics but not the ovulation rate at first oestrus

1992 ◽  
Vol 135 (3) ◽  
pp. 439-446 ◽  
Author(s):  
W. A. van Cappellen ◽  
E. C. M. van Leeuwen ◽  
P. Kramer ◽  
H. M. A. Meijs-Roelofs
Keyword(s):  
Ovarian Follicle ◽  
Ovarian Follicles ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Normal Range ◽  
Juvenile Period ◽  
Unilateral Ovariectomy ◽  
Releasing Hormone ◽  
Total Pool ◽  
Lh Releasing Hormone

ABSTRACT The effect on first ovulation of the massive reduction of the total pool of ovarian follicles during the infantile and late juvenile period was studied in rats. Treatment with an LH-releasing hormone antagonist (LHRH-A) during infancy (5 mg/kg body weight on days 6, 9, 12 and 15 of life) was combined with unilateral ovariectomy performed on either day 15 (early ULO) or 2–5 days before the expected day of first ovulation (late ULO). Rats were killed on the day of first or second oestrus, when blood was collected and the (remaining) ovaries were prepared for differential counting of follicles and corpora lutea. In addition, blood was sampled 8 h after ULO and the ovaries studied histologically in the group of rats which were unilaterally ovariectomized 2–5 days before first ovulation. The time of first ovulation was not influenced by treatment with LHRH-A, early or late ULO, or a combination of LHRH-A treatment and ULO. Ovulation rate after LHRH-A treatment was decreased, but was still within the normal range in intact rats and in early ULO rats compared with saline-treated controls. Serum FSH concentrations 8 h after ULO performed 2–5 days before first ovulation were similar in saline- and LHRH-A-treated rats (845 ± 59 and 801 ± 99 (s.e.m.) μg/l respectively) and had increased compared with intact controls (216 ± 15 μg/l). Treatment with LHRH-A resulted in a reduction of more than 50% in healthy and atretic follicles, and late ULO reduced the number of healthy follicles even further. In saline-treated rats late ULO decreased the rate of atresia, but in LHRH-A-treated rats atresia was not reduced further by (late or early) ULO. It is concluded that even after massive reduction of the pool of ovarian follicles by early LHRH-A treatment combined with late or early ULO, the timing of the first ovulation was normal and ovulation rates, although somewhat lower in some LHRH-A-treated rats, were within the normal range. Journal of Endocrinology (1992) 135, 439–446

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