Induction of haemorrhagic anovulatory follicles in mares

2008 ◽  
Vol 20 (8) ◽  
pp. 947 ◽  
Author(s):  
O. J. Ginther ◽  
M. O. Gastal ◽  
E. L. Gastal ◽  
J. C. Jacob ◽  
M. A. Beg
Keyword(s):  
Prostaglandin F2α ◽  
Post Treatment ◽  
Oestrous Cycle ◽  
Follicular Waves ◽  
Follicular Wave ◽  
High Incidence ◽  
The Future ◽  
The Mean

A follicular wave and luteolysis were induced in mares by ablation of follicles ≥6 mm and treatment with prostaglandin F2α (PGF) on Day 10 (where ovulation = Day 0). The incidence of haemorrhagic anovulatory follicles (HAFs) in the induced waves (20%) was greater (P < 0.007) than in preceding spontaneous waves (2%). Hormone and follicle dynamics were compared between induced follicular waves that ended in ovulations (ovulating group; n = 36) v. HAFs (HAF group; n = 9). The day of the first ovulation or the beginning of HAF formation at the end of an induced wave was designated as post-treatment Day 0. The mean 13-day interval from Day 10 (PGF and ablation) to the post-treatment ovulation was normalised into Days 10 to 16, followed by Day –6 to Day 0 relative to the post-treatment ovulation. Concentrations of LH were greater (P < 0.05) in the HAF group than in the ovulating group on Days 10, 11, 12, 14, –3 and –2. The HAF group had greater (P < 0.003) LH concentrations on Day 10 of the preceding oestrous cycle with spontaneous ovulatory waves. The diameter of the largest follicle was less (P < 0.05) in the HAF group on most days between Day 13 and Day –1 and this was attributable to later (P < 0.002) emergence of the future largest follicle at 6 mm in the HAF group (Day 12.4 ± 0.5) than in the ovulating group (Day 11.3 ± 0.1). The results indicate that the high incidence of HAFs after PGF and ablation was associated with later follicle emergence and immediate and continuing greater LH concentration after PGF treatment, apparently augmented by an inherently high pretreatment LH concentration.

scholarly journals A SOMATOTROFINA BOVINA (bST) E SUA RELAÇÃO COM O RECRUTAMENTO FOLICULAR OVARIANO DURANTE O CICLO ESTRAL DE VACAS

2005 ◽  
Vol 10 (1) ◽  
Author(s):  
L.E. KOZICKI ◽  
M.S. SEGUI ◽  
J.C. FANTINI FILHO ◽  
F.R.A. PRADO ◽  
F. MATTÉ ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Wave Length ◽  
Follicular Development ◽  
Post Treatment ◽  
Maximum Diameter ◽  
Estrus Cycle ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Holstein Friesian ◽  
The Mean

O objetivo do experimento foi testar os efeitos da somatotrofina bovina (BST) no recrutamento de folículos ovarianos, durante o ciclo estral de vacas. Foram utilizadas seis vacas não lactantes Bostrurus taurus antes do experimento, os animais foram submetidos a exames ginecológicos completos, estando o escore médio da condição corporal dos animais em 3,0. As vacas foram divididas ao acaso em dois grupos: G1 - três animais, tratados com somatotrofina bovina recombinante (BST) 500 mg, de liberação lenta com vitamina E (IM); G2 - três vacas controles, que receberam 10 ml (IM) de solução fisiológica estéril como placebo. Para sincronizar o estro base das vacas foram utilizados implantes de norgestomet de 3 mg, na face externa da orelha (SC). O implante permaneceu por 10 dias seguidos nos animais de ambos os grupos e na sua retirada, utilizou-se uma dose de 500 ì g de cloprostenol (IM). No 3º dia pós estro os animais foram tratados respectivamente com BST (G1) e solução fisiológica para os controles (G2). Diariamente, a partir do dia do estro base até o próximo estro, os ovários das vacas foram “monitorados¨ ultrassonograficamente com vistas ao número de folículos recrutados em cada onda folicular, verificação do folículo dominante (FD) e sua evolução, bem como o diâmetro individual dos outros folículos. Para o monitoramento folicular ovariano, foi utilizado aparelho de ultrassonografia e transdutor linear de 5.0 megahertz. Foram detectados durante o ciclo estral em média 8,5 e 8,3 folículos maiores que 4,0 mm de diâmetro nos animais dos G1 e G2 respectivamente; em torno do 10º dia pós tratamento observou-se o maior número de folículos recrutados em ambos os grupos; houve cinco animais com 2 ondas foliculares e um com três, sendo o número de folículos recrutados em cada onda como segue (G1 e G2, respectivamente): 1ª onda 7,6 e 7,0; 2ª onda 8,3 e 8,0; dia da detecção do 1º FD 1,0 e 1,6 dias ; 2º FD 8,6 e 9,0 dias; duração da 1ª onda folicular 11,6 e 9,6 dias; da 2ª onda folicular 8,0 e 7,6 dias; diâmetro máximo do 1º FD 18,2 e 15,8 mm; do 2º FD 16,6 e 15,0 mm; diâmetro do corpo lúteo (CL) do estro base 30,7 e 24,3 mm; dia do diâmetro folicular máximo pós tratamento do FD da 1ª onda: 8,6º e 10,3º; do 2º FD 18,6º e 16,6º dia. Baseados nesses resultados concluiu-se que a aplicação isolada de BST no 3º dia do ciclo estral, não exerceu influência entre os grupos relativamente ao recrutamento folicular ovariano, à exceção da duração da fase luteal, a qual alongou-se significativamente (p0,05) entre os grupos. A administração do BST expressou uma tendência em maior número de folículos recrutados (p>0,05). The bovine somatotrophin in the estrus cycle and its relationships with the ovarian follicular recruitment in cows Abstract The aim of this research was to evaluate the effects of the bovine somatotropin (BST) on the ovarian follicular wave of estrus cycle in cows. Six nonlactating cows Bos taurus taurus, from which four Holstein Friesian, one Jersey and one Holstein-pingzgauer breed, were used. The cows were submitted to a genital examination prior to the experiment, the mean body score condition observed being 3.0. The animals were maintained on oat and azeven pasture, with corn silage and mineral suplementation ad libitum. The cows were ramdomly divided in two groups: G1 – three animals treated with 500 mg BST in the third day post estrus; G2 - three control cows (10 ml physiologic solution). Norgestomet implants on the ear internal face and intramuscular PGF2 alpha were used to perform the estrus synchronization. The bovine ovaries were daily scanned by ultrasound, from the estrus day to the following estrus, in order to detect the follicular development in each follicular wave. During the estrus cycle 8.5 and 8.3 follicles bigger than 4.0 mm of diameter were detected in G1 and G2, respectively. The highest number of recruitment follicles occurred in both groups around the 10th day post treatment; five cows had two follicular waves and the other, one. The number of recruitment follicles in each wave for G1 and G2 group was respectively: 1st wave, 7.6 and 7.0; 2nd wave, 8.3 and 8.0; 1st dominant follicle (FD) detection 1.0 and 1.6 days; 2nd FD detection 8.6 and 9.0 days; 1st follicular wave length, 11.6 and 9.6 days; 2nd follicular wave, 8.0 and 7.6 days. The maximum diameter of the 1st FD was 18.2 and 15.8 mm; from the 2nd FD 16.6 and 15.0 mm; CL diameter from the estrus basis, 30.7 and 24.3 mm; at the day of the major follicular diameter post treatment of the 1st FD (1st wave) 8.6 and 10.3; from the 2nd wave, FD 18.6 and 16.6 day, respectively. In conclusion, the isolated administration of BST in the 3rd day of the estrus cycle did not influence the follicular recruitment between groups, except on the length of the luteal phase (p0.05) between groups. The BST effect appointed a tendency on the greater number of recruitment follicles (p>0,05).

Progesterone as the driving regulatory force behind serum FSH concentrations and antral follicular development in cycling ewes

2011 ◽  
Vol 23 (2) ◽  
pp. 303 ◽  
Author(s):  
Tanya E. Baby ◽  
Pawel M. Bartlewski
Keyword(s):  
Luteal Phase ◽  
Follicular Development ◽  
Treated Group ◽  
Time Frame ◽  
Oestrous Cycle ◽  
Control Group ◽  
Corpora Lutea ◽  
Follicular Waves ◽  
Follicular Wave ◽  
And Control

Ovarian antral follicles in sheep grow in an orderly succession, producing typically three to four follicular waves per 17-day oestrous cycle. Each wave is preceded by a transient increase in circulating FSH concentrations. The mechanism controlling the number of recurrent FSH peaks and emerging follicular waves remains unknown. During the ewe’s oestrous cycle, the time between the first two FSH peaks and days of wave emergence is longer than the intervals separating the ensuing FSH peaks and follicular waves. The prolonged interpeak and interwave interval occurs early in the luteal phase when low levels of progesterone are secreted by developing, or not fully functional, corpora lutea (CL). The purpose of the present study was to determine the effect of varying progesterone (P4) levels on circulating concentrations of FSH and antral follicular development in sheep. Exogenous P4 (15 mg per ewe, i.m.) was administered twice daily to six cycling Rideau Arcott × Dorset ewes from Day 0 (ovulation) to Day 4 (the mean duration of the interwave interval); six animals served as controls. Follicular growth was monitored in all animals by daily transrectal ultrasonography (Days 0–9). Jugular blood samples were drawn twice a day from Day 0 to Day 4 and then daily until Day 9 to measure systemic concentrations of P4, FSH and 17β-oestradiol (E2). The first FSH peak after ovulation was detected on Days 1.5 ± 0.2 and 4.2 ± 0.2 in treated and control ewes, respectively (P < 0.05). The next FSH peak(s) occurred on Day 3.9 ± 0.3 in the treated group and on Day 6.4 ± 0.5 in the control group. Consequently, the treated group had, on average, three follicular waves emerging on Days 0, 3 and 6, whereas the control group had two waves emerging on Days 0 and 5. Mean serum E2 concentrations were greater (P < 0.05) in control compared with treated ewes on Days 1.3, 2.3, 3.3, 4.0 and 4.3 after ovulation. In summary, creation of mid-luteal phase levels of P4 in metoestrus shortened the time to the first post-ovulatory FSH peak in ewes, resulting in the emergence of one more follicular wave compared with control ewes during the same time frame. Therefore, P4 appears to be a key endocrine signal governing the control of periodic increases in serum FSH concentrations and the number of follicular waves in cycling sheep.

scholarly journals Follicular waves and circulating concentrations of gonadotrophins, inhibin and oestradiol during the anovulatory season in mares

Reproduction ◽  
2002 ◽  
pp. 875-885 ◽  
Author(s):  
FX Donadeu ◽  
OJ Ginther
Keyword(s):  
Blood Sample ◽  
Transitional Period ◽  
Follicle Growth ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Mean Diameter ◽  
Concentration Changes ◽  
The Mean ◽  
Temporal Basis ◽  
Follicular Activity

Follicular waves and associated circulating hormone concentrations were studied during the anovulatory season in pony mares (n=8). Follicles were monitored by ultrasonography and a blood sample was taken daily from 29 January until ovulation (mean, 28 April). A mid-anovulatory period (largest follicle, 16.0+/-0.5 mm in diameter) and transitional period (largest follicle, 22.4+/-0.5 mm) were distinctive in each mare. The two periods were delineated by an increase in the diameter of the largest follicle to >/=21.0 mm. Follicular waves, identified by significant increases in the mean diameter of the second to sixth largest follicles, were detected during both the mid-anovulatory and transitional periods. The mean number of follicles >/=15.0 mm in diameter and the diameter of the second to sixth largest follicles increased in association with statistically identified FSH surges. The pattern of the FSH concentration changes during surges did not change during the mid-anovulatory and transitional periods. During the declining portion of the FSH surge, follicle growth continued and circulating total inhibin increased, indicating suppression of FSH by inhibin from the growing follicles. Circulating oestradiol or LH did not change relative to wave emergence. Results indicated that follicular waves occurred during the second-half of the anovulatory season, even during the period of lowest follicular activity. On a temporal basis, follicular wave emergence was stimulated by surges in circulating FSH. However, the increase in follicle growth to >/=21.0 mm in diameter for the wave at the beginning of the transitional period and for the subsequent waves was not attributable to a change in the characteristics of the associated FSH surges.

229 EVALUATION OF OOCYTE QUALITY RECOVERED FROM Gir BREED COWS WITH SYNCHRONIZED FOLLICULAR WAVE ON IN VITRO EMBRYO PRODUCTION

2011 ◽  
Vol 23 (1) ◽  
pp. 213
Author(s):  
L. T. Iguma ◽  
J. N. S. Sales ◽  
R. I. T. P. Batista ◽  
M. M. Pereira ◽  
C. C. R. Quintão ◽  
...  
Keyword(s):  
Cumulus Cell ◽  
Personal Communication ◽  
Fertilization In Vitro ◽  
Embryo Production ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Cell Layers ◽  
The Mean ◽  
In Vitro Embryo Production

Recent data reveal that approximately 80% of bovine embryos produced in vitro worldwide are from (Brazil J. H. M. Viana, personal communication). Adoption of this biotechnology by Brazilian producers might be attributed to particularities of the Bos indicus subspecies. Zebu breeds provide 2 to 3 times more viable oocytes than Bos taurus breeds per ovum pickup (OPU) session. This work aimed to evaluate the quality of cumulus–oocyte complexes (COC) retrieved from Gir breed cows (B. indicus) by OPU with a synchronized follicular wave and subjected to an in vitro embryo production (IVP) technique. All COC were obtained by OPU of 14 Gir cows performed every 14 days. There were 4 OPU sessions, preceded by synchronization of the follicular waves. Wave synchronization was achieved by an injection of 2 mg of oestradiol benzoate followed by the insertion of a norgestomet implant that stayed in place for 5 days. On Day 5, follicles of 2 to 8 mm were aspirated. The oocytes recovered were distributed according to classification: Group 1, with ≥3 cumulus cell layers and homogeneous or slightly heterogeneous cytoplasm (n = 314); and Group 2, ≤2 cumulus cells layers and slightly or coarsely granulated cytoplasm (n = 236). Oocytes from both groups were followed to in vitro maturation–IVF–fertilization–in vitro culture. Two (Day 2) and 8 (Day 8) days after the beginning of fertilization, the cleavage and blastocyst rates were measured, respectively. The statistical analyses were performed using a chi-square test (P < 0.05). The mean cleavage rates observed were 72.93 and 69.07% (not significant), whereas the mean blastocyst rates were 37.90 and 17.80%, and were significantly different for Groups 1 and 2, respectively. The results suggest that the morphology of oocytes (number of cumulus cell layers and cytoplasm homogeneity) is a strong indicator of the in vitro developmental capacity of oocytes recovered from Gir cows with synchronized follicular waves, although we did not observe compromised cleavage rates. Financial support was provided by Fapesp/Fapemig/CNPq/Embrapa. Epamig/Faz. Calciolândia/Nutricell–Nutrientes Celulares is acknowledged.

171 ADMINISTRATION OF GnRH ON DAY 6 ALTERS THE NUMBER OF FOLLICULAR WAVES FROM 2 TO 3 DURING THE ESTROUS CYCLE OF HOLSTEIN COWS

2009 ◽  
Vol 21 (1) ◽  
pp. 184
Author(s):  
E. Dirandeh ◽  
H. Kohram ◽  
A. Zare Shahneh
Keyword(s):  
Estrous Cycle ◽  
Prostaglandin F2α ◽  
Control Treatment ◽  
Control Group ◽  
Third Wave ◽  
Estrous Cycles ◽  
Follicular Waves ◽  
Follicular Wave ◽  
Lactating Cows ◽  
Ovulatory Follicle

It is suggested that pregnancy rate is greater in lactating cows inseminated following ovulation of a third-wave follicle compared with a second-wave follicle. The number of follicular waves is not apparent during the estrous cycle. However, GnRH injection on Day 6 is supposed to initiate a new follicular wave earlier; as a result, the number of cows with 3 follicular waves will be increased. This study was done to change the 2-follicular-wave cycles to 3 follicular waves during the estrous cycle. The estrous cycles of 10 cows were synchronized with 2 i.m. injections of prostaglandin F2α given 11 days apart. The cows were randomly assigned to 1 of 2 treatments. Cows in the control treatment received no treatment, whereas GnRH6 cows received a GnRH injection on Day 6 of the estrous cycle (estrus = Day 0). Ovaries of all cows were scanned daily, from estrus (Day 0) to the subsequent estrus (Day 23). Profiles of the mean number of follicles (i.e. 4- to 6-mm and ≥7 mm), the diameter of the largest follicle (F1), and comparison of 2- and 3-wave cows were compared by least squares analysis of variance using the general linear model (GLM) procedure of SAS. The number of 4 to 6 mm follicles had a tendency to decline until Day 6 (3.0 ± 2.1 v. 0.8 ± 1.6). In response to an injection of GnRH, the number of small follicles in group GnRH6 on Day 6 (1.5 ± 1.6 follicles) increased (P < 0.05) on Day 8 (5.0 ± 1.7 follicles) and the number of medium and large follicles (≥7 mm) on Day 6 (1.8 ± 0.5 follicles) decreased (P < 0.05) on Day 9 (0.8 ± 0.6 follicles). Over the 4-day period before GnRH treatment, the diameter of F1 was increasing (from 4.7 ± 0.9 mm to 10.0 ± 0.6 mm) in cows treated with GnRH on Day 6 of the estrous cycle; thereafter, the diameter of the F1 decreased (P < 0.05) within 2 days of GnRH treatment. In the control group the diameter of the F1 increased over the 4-day period before GnRH treatment (from 5.0 ± 0.9 mm to 11.2 ± 0.6 mm), whereas it remained constant (11.2 ± 1.2 mm to 11.2 ± 1.2 mm) between Days 6 and 9 of the estrous cycle (P < 0.003). Results showed that 4 out of 5 cows in control group had 2 follicular waves, whereas all of the cows (n = 5) in GnRH6 group had 3 follicular waves. The first follicular wave begins at Day 1.1 ± 0.50 and 0.70 ± 0.50 in the control and GnRH groups, respectively. The second follicular waves appeared at Day 11.00 ± 0.80 and 8.30 ± 1.50 (P ≤ 0.05) for the 2- and 3-wave animals, respectively. The third follicular waves (n = 6) initiated at Day 16.30 ± 1.50. Cows with 2 follicular waves had shorter estrous cycles (P ≤ 0.05) than 3-wave cows (20.50 ± 0.60 v. 22.40 ± 0.90). The ovulatory follicle in 2-wave cows grew larger (14.00 ± 1.80 v. 12.50 ± 0.90 mm; P ≤ 0.05), and maintained for a longer period of time (9.50 ± 1.80 v. 6.1 ± 0.90; P ≤ 0.05) than in 3-wave cows. In conclusion, an injection of GnRH on Day 6 of the estrous cycle could promote the emergence of a new follicular wave earlier in cows and alter the estrous cycles with 2 waves into 3 follicular waves.

scholarly journals Superovulation following follicular synchronization with GnRH at random stages of the oestrous cycle in heifers

2011 ◽  
Vol 56 (No. 1) ◽  
pp. 7-14
Author(s):  
H. Kohram ◽  
V. Vahedi ◽  
S. Nasrollahi ◽  
A. Farahavar
Keyword(s):  
Oestrous Cycle ◽  
Control Group ◽  
Follicular Waves ◽  
The Mean ◽  
Follicular Puncture ◽  
Conventional Manner

The objective of this study was to develop a superovulatory program based on synchronization of follicular waves with GnRH which could be applied regardless of the stage of the oestrous cycle. 36 heifers were subjected to this experiment and GnRH (Cystorelin, 200 &micro;g) was applied between Days 0 and 7 (n = 15), 8 and 12 (n = 8) or 13 and 20 (n = 13) of the oestrous cycle. Four days after GnRH treatment, all follicles &ge; 6 mm of heifers (n) were either punctured (n = 21) or left intact (n = 15). All heifers were superstimulated from Day 6 to Day 10 after GnRH treatment with 320 mg Folltropin-V. In parallel, 21 heifers were superstimulated in a conventional manner (Days 8 to 12) and were used as controls. The homogeneity of follicular inventories among Stage-groups occurred within 4 days of GnRH treatment for follicles &ge; 7 mm but only 2 days after follicular puncture for follicles 4 to 6 mm. In response to the follicular puncture, the mean number of follicles 4 to 6 mm increased in heifers of the punctured group (P &lt; 0.01). Following the superstimulation, the follicular (P &lt; 0.01) and ovulatory (P &lt; 0.01) responses were higher in the punctured group than in the nonpunctured group. The in vivo production of transferable embryos in the punctured group was similar to that of the nonpunctured group but it was lower (P &lt; 0.01) than in heifers of the control group. In conclusion, results from the present study indicate that regardless of the stage of the oestrous cycle, the homogeneity of follicular inventories following the follicular synchronization is obtained using GnRH treatment and follicular puncture. The in vivo production of embryos was severely compromised in the present study with heifers. Causes of such reduction in the in vivo production of embryos are still unknown.

scholarly journals 217LUTEAL REGRESSION AND FOLLICLE DEVELOPMENT FOLLOWING PROSTAGLANDIN-F2± TREATMENT 3 DAYS AFTER OVULATION IN MARES

2004 ◽  
Vol 16 (2) ◽  
pp. 230
Author(s):  
D.R. Bergfelt ◽  
R.A. Pierson ◽  
O.J. Ginther
Keyword(s):  
Prostaglandin F2α ◽  
Post Treatment ◽  
Maximum Diameter ◽  
Functional Regression ◽  
Treatment Groups ◽  
Scale Scores ◽  
Luteal Tissue ◽  
Potential Benefits ◽  
The Mean ◽  
The Difference

The corpus luteum (CL) is responsive to exogenous prostaglandin-F2α (PGF) 1 to 2 days after ovulation in the mare (Troedsson et al. 2001 Theriogenology 55, 1891–1899); however, complete and sustained demise of the CL beginning less than 5 days after ovulation in response to PGF treatment has not been documented. The present study was designed to compare the morphological and physiological response of the primary CL to PGF given at early diestrus with a more conventional treatment given at about mid-cycle. In addition, follicle status pre- and post-treatment were examined and compared between the treatment groups. On the day of pretreatment ovulation (Day 0), riding-type horse mares were randomly assigned to receive a single dose of PGF (Lutalyse, Upjohn, Kalamazoo, MI, USA;; 10mg/mare, i.m.) on Day 3 (n=17) or Day 10 (n=17). Beginning on either Days 3 or 10, transrectal ultrasonography was used to determine follicle and CL diameters, determine luteal tissue gray-scale scores (echogenicity), and to detect ovulation. Follicular and luteal measurements and jugular blood samples were collected daily until the post-treatment ovulation. Structural and functional regression of the CL was indicated by: 1) a progressive decrease (day effect;; P&lt;0.0001) in mean diameter of the CL beginning 24h after PGF treatment in the Day 3 and Day 10 groups;; 2) a precipitous decrease (P&lt;0.009) in mean plasma progesterone concentrations within 24h in both groups followed by a more gradual decline to basal concentrations by the second day in the Day 10 group or after the fourth day in the Day 3 group;; and 3) an increase (P&lt;0.02) in mean luteal tissue echogenicity in both groups after the second day following PGF treatment. The mean intervals from PGF treatment to ovulation were not different (P&gt;0.2) between groups (combined, 9.9 days) but the mean (±SEM) interovulatory interval was shorter (P&lt;0.0001) in the Day 3 group (13.2±0.9 days;; range, 7 to 20 days) than in the Day 10 group (19.2±0.7 days;; range, 14 to 26 days). The greater the diameter of the largest follicle at the time of PGF treatment, the shorter the interval to post-treatment ovulation in the Day 3 (r=−0.57, P&lt;0.02) and Day 10 (r=−0.74, P&lt;0.001) groups. Growth rates of the preovulatory follicles were similar (P&gt;0.59) between groups (combined, 3.6mm/day) but the maximum diameter was smaller (P&lt;0.05) in the Day 3 group (40.5±1.2mm) compared to the Day 10 group (43.4±0.8mm). Unexpectedly, more (P&lt;0.03) double ovulations occurred in the Day 3 group (6/17, 35%) than in the Day 10 group (1/17, 6%). In conclusion, an immature CL at early diestrus responded to PGF treatment in a manner comparable to a mature CL at mid-cycle. The Day 3 group ovulated an average of 6 days earlier than the Day 10 group as a result of the difference in timing of the PGF treatment between groups. Thus, these results warrant a reassessment of the prevailing concept that the equine CL is resistant to PGF-induced regression before 5 days after ovulation, especially when considering the potential benefits of a shortened interovulatory interval and an increased double ovulation rate.

178 IS PROGESTERONE THE DETERMINING REGULATORY FACTOR BEHIND OVULATION RATE IN EWES?

2015 ◽  
Vol 27 (1) ◽  
pp. 180
Author(s):  
J. Sohal ◽  
V. Paravinja ◽  
T. Baby ◽  
M. Murawski ◽  
T. Schwarz ◽  
...  
Keyword(s):  
Luteal Phase ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Antral Follicles ◽  
Follicular Waves ◽  
Lh Pulsatility ◽  
Lh Release ◽  
The Mean ◽  
Number Percentage ◽  
Ovulatory Follicles

Ovarian antral follicles in the ewe grow in an orderly succession, producing 3–4 waves per oestrous cycle. In prolific sheep, some large antral follicles from the second-last wave of the oestrous cycle are added to the ovulatory follicles emerging just before oestrus to give a higher ovulation rate; it is feasible that regression of these follicles is prevented by an increase in serum concentrations of FSH and/or LH pulsatility at pro-oestrus. Prolific sheep tend to have a shorter luteal phase than non-prolific breeds and there is a great deal of evidence that luteal progesterone (P4), in addition to regulating LH release, may govern the secretion of FSH heralding the emergence of follicular waves. The specific purpose of the present experiments was to determine whether or not extending the duration of the luteal phase would alter the ovulation rate in prolific sheep. In both studies, exogenous P4 (7.5 mg ewe–1 IM) was administered on Days 11 and 12 (Day 0 = ovulation) in moderately prolific Rideau Arcott x Polled Dorset (Exp. 1, n = 8) and highly prolific Olkuska ewes (Exp. 2, n = 7), while the equinumerous groups of animals served as controls (CTR). Transrectal ovarian ultrasonography was performed daily and jugular blood samples were drawn twice a day from Day 9 until ovulation. All single-time point observations were compared between groups by Student t-test. Progesterone injections resulted in uniform increments in serum P4 levels in all animals allocated to the treatment (TRT) groups. However, the mean duration of the interovulatory interval did not differ (P > 0.05) between TRT and CTR groups of ewes in both experiments. The mean (± s.e.m.) ovulation rate was 1.6 ± 0.2 v. 3.2 ± 0.4 (Exp. 1; P < 0.001) and 3.2 ± 0.8 v. 4.0 ± 1.0 (Exp. 2; P < 0.05) in TRT v. CTR ewes, respectively. There were no differences in terms of the timing of penultimate and final wave emergence between the two subsets of animals studied in either experiment. The number/percentage of ovulating follicles from the penultimate wave of the interovulatory interval studied was 0.25 ± 0.16 v. 1.75 ± 0.45 (P < 0.01)/25.0 ± 16.4% v. 75.0 ± 16.4% (P < 0.05) in Exp. 1 and 0.50 ± 0.30 v. 1.60 ± 0.40 (P < 0.05)/13.8 ± 9.0% v. 53.4 ± 16.7% (P < 0.05) in Exp. 2, in TRT v. CTR animals, respectively. In summary, administration of P4 at the end of diestrus reduced the incidence of ovulations from the penultimate wave of the oestrous cycle in moderately and highly prolific strains of sheep. Therefore, progesterone appears to be a key endocrine signal governing the ovulation rate in cyclic sheep, presumably by acting directly at the level of the ovary. The present results may pave a way to devising a simple and inexpensive method of controlling lamb productivity in commercial flocks of sheep and fertility in other polyovulatory species.

121 Ovulatory response to gonadotropin-releasing hormone relative to day and diameter of dominant follicle during the first follicular wave in Beetal goats

2019 ◽  
Vol 31 (1) ◽  
pp. 186
Author(s):  
W. Ahmad ◽  
M. I.-R. Khan ◽  
A. Murtaza ◽  
I. Mohsin ◽  
A. Riaz ◽  
...  
Keyword(s):  
Growth Rate ◽  
Prostaglandin F2α ◽  
Binary Logistic Regression ◽  
Gonadotropin Releasing Hormone ◽  
Oestrous Cycle ◽  
New Wave ◽  
Dominant Follicle ◽  
Releasing Hormone ◽  
Follicular Wave ◽  
Ovulatory Follicles

In Beetal goats under subtropical conditions, ovulatory response of first-wave dominant follicle based on diameter and day of oestrous cycle is unknown to date. The objective of this study was to evaluate the ovulatory response to gonadotropin-releasing hormone (GnRH) relative to day and diameter of dominant follicle during the first follicular wave in Beetal goats. Fifty goats were synchronized using a single dose of prostaglandin F2α (75 µg; D+ cloprostenol, Fatro, Italy), and scanned every 6 hours for ovulation using a 7.5-MHz trans-rectal transducer (Honda HS: 1500, Japan). Following ovulation (Day 0), goats (n=40; 10/day) were given GnRH (25µg lecirelin, Fatro, Italy) on Days 2, 4, 6, and 8 of oestrous cycle. Follicular dynamics was monitored daily from D 0 until GnRH, and every 4 hours after GnRH until ovulation. Ovulation frequency relative to day and dominant follicular diameter was analysed by binary logistic regression, whereas diameter of dominant follicle at time of GnRH, ovulation time, time of wave emergence and growth rate of dominant follicle following GnRH were analysed by one-way ANOVA and independent sample t-test (SPSS 20, IBM Corp., Armonk, NY, USA). Eighty percent of the goats ovulated within 74.7±1.3h after prostaglandin F2α. Overall, 37% (14/38) of the goats ovulated following GnRH within 12.0±1.5h. Ovulations (%) following GnRH were higher (P=0.03) on Day 4 than 2 (60 v. 10%; i.e. 14 times higher than Day 2) and decreased gradually from Day 4 to 8 (P&gt;0.05). Similarly, ovulations following GnRH were higher (P=0.00) in first-wave dominant follicles having diameter 6.1-7.0mm than those having less than 6.1mm (88v. 23%; i.e. 24 times higher than &lt;6.1mm). Ovulations (%) decreased as the diameter of dominant follicle increased from 6.1-7.0mm (P&gt;0.05). Diameters of ovulatory follicles at time of GnRH between Day 2, 4, 6, and 8 were not different (P&gt;0.05). Regardless of day of GnRH treatment, diameter of ovulatory v. anovulatory follicles differed (6.44±0.03v. 5.1±0.4 mm; P=0.00). Overall, growth rate of dominant follicles following GnRH was 0.2±0.11mm and did not differ between ovulatory and anovulatory goats (0.29±0.13v. 0.13±0.15 mm; P&gt;0.05). Interval to the emergence of a new wave following GnRH was prolonged for Day 4 compared to Day 2, 6, and 8 (i.e. 22v. 8, 11, and 12 h; respectively, P&lt;0.05). In conclusion, GnRH treatment at Day 4 resulted in maximum ovulations as the first-wave dominant follicle reached a size of 6.1 to 7.0 mm.

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