Follicular dynamics during the pre-ovulatory and subsequent first follicular wave stages affect the pregnancy outcome in Japanese Black cows

We have developed an experimental model in which groups of ewes are simultaneously experiencing the first ovarian follicular wave of their oestrous cycle. We used this ‘first-wave model’ in a 2×2 factorial experiment (ten ewes per group) to study the effect of body condition (BC) and a short-term supplement on follicular dynamics and ovulation rate. The ‘first-wave’ was established by giving ewes three injections of prostaglandin (PG), 7 days apart. The 6-day supplement (lupin grain) began 2 days after the second PG injection and continued until the third. Follicles were studied by ultrasound, and blood was sampled to measure glucose and hormones. The supplement increased (P<0.01) the concentrations of glucose, insulin and leptin, decreased FSH concentrations (P<0.01) and tended to increase oestradiol concentrations (P=0.06). The supplement tended to increase the number of 3 mm follicles (P=0.06). Compared with low-BC ewes, high-BC ewes had more follicular waves (P<0.05), higher concentrations of insulin, leptin and IGF1 (P<0.05) and tended to have higher FSH concentrations (P=0.09). Leptin and insulin concentrations remained high until the end of supplementation in high-BC ewes, whereas they decreased after the third day of supplementation in low-BC ewes. In conclusion, high concentrations of metabolic hormones in fat ewes are associated with the development of more follicular waves. When a supplement is superimposed on this situation, changes in glucose and metabolic hormones allow more follicles to be selected to ovulate.

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Ovarian Follicular Dynamics during the Estrous Cycle in Jennies in Upper Egypt

Veterinary Medicine International ◽

10.4061/2011/860518 ◽

2011 ◽

Vol 2011 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

R. I. Derar ◽

H. A. Hussein

Keyword(s):

Growth Rate ◽

Estrous Cycle ◽

Slow Rate ◽

Ovarian Follicles ◽

Maximum Diameter ◽

Dominant Follicle ◽

Upper Egypt ◽

Follicular Wave ◽

Preovulatory Follicles ◽

Follicular Dynamics

The objective of the current study was to describe follicular dynamics in Egyptian Jennies throughout the estrous cycle. In this experiment, 8 estrus cycles in 8 cyclic Jennies were studied from February to June using ultrasonography. The result revealed that one follicular wave per cycle was recorded throughout the studied period. Dominant follicle (DF) was firstly detected at day in Jennies. The growth rate of DF was mm/day. Left ovulations were nonsignificantly () more than right ovulations (55.6% versus 44.6%). The CL was firstly detected at D , developed in a rate of mm/day, reached a maximum diameter of mm at D , and started to regress on D with a mean regression rate of mm d-1. Results of the present study indicated that Jennies had one follicular wave per cycle. The Day of the cycle has a significant effect on the number of different classes of the ovarian follicles, but not large ones. Ultrasonographic characteristics of the preovulatory follicles could be useful to predict ovulation. CL developed and regressed in a slow rate.

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174 EVALUATION OF THE 9-DAY PROTOCOL FOR ESTROUS SYNCHRONIZATION IN SANTA INÊS EWES

Reproduction Fertility and Development ◽

10.1071/rdv23n1ab174 ◽

2011 ◽

Vol 23 (1) ◽

pp. 189

Author(s):

P. Viau ◽

M. B. Paes de Barros ◽

L. M. K. Dias ◽

S. S. Nicolau ◽

C. T. Marino ◽

...

Keyword(s):

Solid Phase ◽

Device Removal ◽

Intact Male ◽

Estrous Synchronization ◽

Follicular Wave ◽

Vaginal Progesterone ◽

Device Placement ◽

Santa Inês ◽

Veterinary Hospital ◽

Follicular Dynamics

The objective of the present study was to characterise follicular dynamics in Santa Ines (SI) during a 9-day protocol for oestrous synchronization and to evaluate the efficiency of the vaginal progesterone-releasing device Primer-PR® (Tecnopec, Brazil). Cyclic females were used (n = 10) at the ruminant sector of the veterinary hospital of the FMVZ–USP, in March 2009. The animals had body scores between 2.5 and 3 and were of proven fertility. Ultrasound examinations were performed using an ALOKA SSD-500 Scanner (Berger, Brazil) with a linear 5.0-MHz transducer, attached to a handle to allow safe intrarectal manipulation. Examinations were performed daily from 3 days (D-3) before the day of device placement (D0) until the day of device removal (D9), and twice daily from device removal until ovulation. All ewes received 0.03 mg of prostaglandin (D-cloprostenol, Prolise®, Tecnopec, Brazil) on D9. Ovulation was assessed by the disappearance of the growing larger follicle or follicles present in the previous examinations. Oestrous detection was performed using an intact male 3 times a day (at 10:00 a.m., 6:00 p.m., and 12:00 p.m.) from D9 until the last acceptant ewe, and blood samples were taken by jugular puncture for progesterone (P4) measurement by radioimmunoassay on solid phase (COAT-A-COUNT, Siemens, USA) from D-3 until the day of ovulation. Data were analysed by Shapiro–Wilk (PROC UNIVARIATE) using the SAS program (SAS Institute Inc., Cary, NC, USA, 2001) and shown as mean ± standard deviation. Plasma P4 concentrations between D0 and D9 were 6.56 ± 2.32 ng mL–1, peaking between D3 and D5 (8.07 ± 2.31 ng mL–1). Oestrous behaviour was shown 45.6 ± 12.71 h after Primer-PR® removal. The first and the last ewe that showed oestrous behaviour was at 30 h and 66 h after Primer-PR® removal, respectively, and the majority of ewes (50%) at 42 h. Oestrous lasted 26.40 ± 9.47 h, and the majority of ewes (70%) showed oestrous behaviour during 24 h. Ovulation occurred 73 ± 14.38 h after Primer–PR® removal and 1.3 ± 0.48 ovulations per animal were observed. From all growing presumptively dominant follicles observed, 92.3% of them ovulated. When double ovulations occurred (n = 3), the interval between first and second ovulation was 16 ± 6.93 h. Emergence of the ovulatory follicular wave occurred at 8.5 days + 16 h after Primer–PR® insertion. The follicles observed to continue growing had a diameter of 3.48 ± 0.28 mm when they were first detected and reached 5.63 ± 0.66 mm, with a growth rate of 0.73 ± 0.43 mm per day. A standard follicle wave within the 9-day protocol was not possible to determine, and the follicles receded in up to 4 days. In conclusion, placement of a Primer-PR® device for 9 days resulted in synchronous oestrus and ovulation in Santa Inês ewes. FAPESP, CAPES, Tecnopec.

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Ovarian follicular dynamics and endocrine profiles in Polwarth ewes with high and low body condition

Animal Science ◽

10.1017/s1357729800052693 ◽

2002 ◽

Vol 74 (3) ◽

pp. 539-545 ◽

Cited By ~ 22

Author(s):

C. Viñoles ◽

L. J. Harris ◽

M. Forsberg ◽

G. Banchero ◽

E. Rubianes

Keyword(s):

Body Condition ◽

Follicular Development ◽

Extended Period ◽

Inhibitory Effect ◽

Follicular Phase ◽

Follicular Waves ◽

Follicular Wave ◽

Similar Inhibitory Effect ◽

Turn Over ◽

Follicular Dynamics

AbstractIn this investigation we tested the hypothesis that static body condition (BC) of the ewe affects oestradiol and FSH with implications for subsequent follicular growth and turn-over. Sixteen Polwarth ewes were selected from a flock according to their BC score (scale: 1 emaciated; 5 obese). High BC (HBC) ewes (no. = 8) had a BC score of 4·1 (s.e. 0·1) and low BC (LBC) ewes (no. = 8) had a BC score of 1·9 (s.e. 0·1). Daily ultrasound examinations were performed and blood samples for progesterone, oestradiol and follicle-stimulating hormone (FSH) determination were collected. All HBC ewes (8/8) exhibited three waves of follicular development, while four LBC ewes (4/8) had two waves and the other four (4/8) had three waves of follicular development (P ≤ 0·05) during the interovulatory period. Overall, the emergences of 33 out of 44 follicular waves were preceded by significant increases in FSH concentrations. Maximum FSH concentrations were detected 0·9 ± 0·2 days before wave emergence. Oestradiol concentrations increased significantly during the growing phase in 38 out of 44 large follicles. A negative correlation between oestradiol and FSH was observed in HBC ewes. A similar inhibitory effect of oestradiol on FSH was observed in LBC ewes, irrespective of whether they developed two or three follicular waves. However, a longer period with high FSH was needed to promote the emergence of the second follicular wave in two-wave LBC ewes. Four HBC ewes had twin ovulations but no LBC ewes did (P ≤ 0·05). In HBC ewes, the follicular phase was characterized by lower oestradiol (6·5 (s.e. 1·0) pmol/l) but higher mean FSH concentrations (2·4 (s.e.0·4) μg/l) than in LBC ewes (8·9 (s.e. 1·2) pmol/l and 2·0 (s.e. 0·3) μg/l, respectively; P ≤ 0·05). The present results suggest that BC influences the pattern of follicular dynamics through changes in the endocrine milieu. Higher FSH concentrations during the follicular phase in HBC ewes, which allowed an extended period of follicular recruitment from a significantly larger pool of small antral follicles could explain the higher ovulation rate observed in this group.

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Follicular dynamic and repeatability of follicular wave development in Peranakan Ongole (PO) cattle

Jurnal Ilmu Ternak dan Veteriner ◽

10.14334/jitv.v21i1.1349 ◽

2016 ◽

Vol 21 (1) ◽

pp. 26 ◽

Cited By ~ 1

Author(s):

Muhammad Imron ◽

Iman Supriatna ◽

. Amrozi ◽

Mohamad Agus Setiadi

Keyword(s):

Bos Taurus ◽

Research Result ◽

Bos Indicus ◽

Follicular Development ◽

Wave Pattern ◽

Follicular Wave ◽

Follicle Diameter ◽

Wave Patterns ◽

The Difference ◽

Follicular Dynamics

<p class="abstrak2">Superovulation treatment on PO cattle (Bos indicus) was less responsive compared to Bos taurus breed. It might due to the difference of their follicular dynamic. This study was conducted to investigate the follicular dynamics and its repeatability in PO cattle. Follicular dynamics observations conducted on 9 cows trough ultrasound scanning every day. Observations of wave patterns repeatability were performed in 6 cows which its wave pattern already known on the next consecutive IOI. Research result indicated that PO cattle had 3 (66%) and 4-waves (34%) pattern. The first wave of 3 and 4-waves pattern emerged on day -0.4+0.9 and 1.4+1.1 respectively. The second wave of 3 and 4-wave pattern emerged on day 9.8+1.5 and 7.4+1.9 respectively. The pattern of 3 waves has a longer follicle dominant duration (11.6+1.5 day) in the first wave of estrous cycle, compared with 4 waves pattern (10+2.92 and 7+1.00 day respectively). The growth rate of dominant follicle was not different significantly between the 3 and 4-waves pattern (0.87+0.23 and 0.94+0.25 mm/day respectively). Similarly, ovulatory follicle diameter between 3 and 4-waves pattern was also not different significantly (12.24+12.34 and 12.30+12.23 mm respectively). Observation of wave patterns repeatability in 6 PO cows indicated that PO cattle had high repeatability in follicular wave pattern (0.88) and the number of growing follicle was 0.91. This study resulted data for dynamic of follicular development, wave pattern, its repeatability which be expected to design the protocol of superovulation treatment or other reproduction technologies based on follicular dynamic to improve its result in PO cattle.</p><p> </p>

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231 SUPEROVULATORY RESPONSE AND EMBRYO YIELD OF SANTA INES EWES SUBMITTED TO FOLLICLE STIMULATING HORMONE TREATMENTS STARTED NEAR THE TIME OF EMERGENCE OF THE FIRST AND LAST FOLLICULAR WAVE OF A PROGESTERONE-BASED PROTOCOL

Reproduction Fertility and Development ◽

10.1071/rdv24n1ab231 ◽

2012 ◽

Vol 24 (1) ◽

pp. 228

Author(s):

M. E. F. Oliveira ◽

C. C. D'Amato ◽

L. G. Oliveira ◽

S. D. Bicudo ◽

J. F. Fonseca ◽

...

Keyword(s):

Buenos Aires ◽

Animal Health ◽

Follicle Stimulating Hormone ◽

Corpora Lutea ◽

Chi Square ◽

Follicular Waves ◽

Follicular Wave ◽

Embryo Yield ◽

Santa Inês ◽

Follicular Dynamics

This study was designed to investigate if the superovulatory response and embryo yield in Santa Ines ewes are influenced by the time that FSH treatments are inititiated: near the emergence of the first or last follicular wave of a progesterone-based (P4) protocol. Days of emergence of the follicular waves was defined in a previous study that evaluated follicular dynamics in oestrus synchronization treatments (Oliveira et al. 2011 Acta Sci. Vet. 40). Twenty Santa Ines cyclic ewes were submitted to 2 superovulatory protocols according to the time that FSH treatments were initiated (G-first wave, n = 10 and G-last wave, n = 10). Thus, the FSH treatment started on Day 4 and 10 of protocol for G-first and G-last, respectively (Day 0 = onset of protocol). Ewes were treated with a P4 device (CIDR®; Pfizer-New Zealand) for 6 and 12 days for G-first and G-last, respectively. Additionally, in G-last, the CIDR was replaced by a new one on Day 7. All ewes received 2 injections of 37.5 μg of D-cloprostenol (Prolise®, Arsa-Argentina) on Day 0 and at CIDR removal. The superovulatory regimen consisted of 8 IM injections of pFSH (Folltropin®; Bioniche Animal Health, Belleville, Ontario, Canada) administrated twice daily (40, 40, 30, 30, 20, 20, 10 and 10 mg of porcine FSH). A single IM dose of 200 IU of eCG (Novormon®, Syntex, Buenos Aires, Argentina) was given concurrently with CIDR removal. Ewes were mated by a fertile ram. Embryo collections were accomplished 7 days after CIDR removal. The superovulatory response was classified in scores: (0) 4 or fewer corpora lutea (CL); (1) between 5 and 10 CL and (2) 11 or more CL. Means (± SD) were compared using Kruskal-Wallis test and percentages using Chi-square (P < 0.05). Most donors (70%, 7/10) from G-last had a superovulatory response classified as score 2 and the remainder (30%, 3/10) as score 1, whereas half of ewes from G-first were classified as score 2 and half as score 1 (P > 0.05).There was no effect between treatments (P > 0.05) for ovulation rate (G-first: 90.7 ± 10.2% vs G-last: 93.0 ± 7.2%), number of ovulations (G-first: 13.1 ± 7.3 vs G-last: 14.0 ± 5.8), or number of luteinized unovulated follicles (G-first: 1.4 ± 1.3 vs G-last: 0.9 ± 1.0). Furthermore, there was no effect between G-first and G-last (P > 0.05) in the rate of ova/embryos recovered (55.1 ± 27.1% vs 67.0 ± 19.4%), mean number of ova/embryos recovered (7.0 ± 5.5 vs 9.1 ± 3.8), number of viable embryos (3.9 ± 6.1 vs 5.7 ± 4.4), or viability rate (49.1 ± 43.7 vs 58.5 ± 34.6). In conclusion, superovulatory response and embryo yield did not differ between FSH treatments initiated during the first or last follicular wave of a progesterone-based treatment in Santa Ines ewes. Financial support of FAPESP is acknowledged.

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36 FOLLICULAR DYNAMICS IN PROLIFIC SHEEP: PGF-BASED ESTRUS SYNCHRONIZATION

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab36 ◽

2010 ◽

Vol 22 (1) ◽

pp. 176

Author(s):

L. Proctor ◽

D. Tutt ◽

D. Olliver ◽

S. Galloway ◽

J. L. Juengel ◽

...

Keyword(s):

Animal Health ◽

T Test ◽

Corpora Lutea ◽

Follicular Wave ◽

Follicle Diameter ◽

Array Transducer ◽

Significant Difference ◽

Preovulatory Follicles ◽

Student’S T ◽

Follicular Dynamics

A study was designed to compare the effect of a prostaglandin-based synchronization protocol on ovarian follicular dynamics in sheep with the FecB (Booroola) mutation. Forty dry Romney sheep (57.6 ± 7.3 kg; 6.1 ± 1.1 years) were randomly selected from both Invermay Booroola (BB; n = 20) and commercial (non-FecB carriers, ++; n = 20) flocks. All ewes had their estrous cycles synchronized with 2 i.m. injections of PGF (150 μg of cloprostenol, Estrumate, Schering-Plough Coopers Animal Health Ltd., New Zealand) administered 7 days apart. Ewes were monitored by transrectal ultrasonography (Aloka 900-SSD and a 7.5-MHz linear-array transducer, Aloka, Tokyo, Japan) daily from Day -2 to the day of ovulation. Data were analyzed by Student’s t-test or Wilcoxon Rank Sum test. Variances were compared with Barlett’s test. Paired t-test compared the number of preovulatory follicles in each genotype after PGF treatments and intervals from PGF to ovulation after PGF. Data are presented as mean (± SEM). The number of corpora lutea (CL) and total CL area at the time of the first and second PGF treatment were 4.4 ± 0.6; 5.7 ± 1.4 and 672.1 ± 133.5 mm2; 999.0 ± 145.9 mm2 in the BB and 2.1 ± 0.2; 2.1 ± 0.5 and 342.3 ± 60.7 mm2; 401.3 ± 68.6 mm2 in ++ ewes, respectively. These 2 variables were higher (P < 0.01) at both PGF injections in the BB than in the ++ ewes, except the CL area at the time of first PGF treatment (P = 0.15). The largest follicle diameter at the time of the first and second PGF treatments was smaller (P < 0.003) in BB (4.1 ± 0.3 mm; 3.5 ± 0.2 mm) than in ++ (5.3 ± 0.3 mm; 5.8 ± 0.1 mm) ewes. The median and mean number of follicles that ovulated after the first and second PGF treatment were higher (P < 0.0001) in BB (6 & 7; 5.7 ± 0.3; 6.9 ± 0.3; difference = 1.2 ± 0.4; P < 0.003) than in the ++ (2 & 2; 2.1 ± 0.1; 2.1 ± 0.1) sheep. The luteal area at the time of first and second PGF in both BB and ++ did not differ (P = 0.3). The intervals from the first and second PGF to the respective ovulations did not differ (P > 0.61) between BB (3.4 ± 0.2; 3.0 ± 0.3d) and ++ (3.5 ± 0.2d; 3.0 ± 0.1d) ewes. However, interval from the second PGF to ovulation was more variable (P = 0.002) in the BB than in the ++ ewes. Data of both groups were combined and a mean significant difference of 0.6 ± 0.2d (P < 0.003) was found between the first and second PGF-to-ovulation intervals. The interval from the first PGF to emergence of the next follicular wave was shorter (P < 0.02) and more variable (P < 0.03) in the BB (2.7 ± 0.4d) than in the ++ (3.5 ± 0.2 d) group. Preovulatory follicles were smaller in Booroola, but higher in number, than in ++ ewes, whereas the luteal area was similar. Within the BB ewes, the higher number of follicles that ovulated after the second PGF than after the first injection may be due to a higher follicular response to an elevated rebound in circulating FSH after the first PGF. A high number of growing follicles of the first follicular wave may also have contributed to this event. These findings warrant further research aimed at the study of the interaction between FSH and follicle dynamics in estrus synchronized sheep carrying the FecB mutation.

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15EFFECT OF DOSE OF ESTRADIOL VALERATE ON OVARIAN FOLLICULAR DYNAMICS IN CIDR-TREATED BEEF COWS

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab15 ◽

2004 ◽

Vol 16 (2) ◽

pp. 130 ◽

Cited By ~ 3

Author(s):

R.J. Mapletoft ◽

M.G. Colazo ◽

J.A. Small ◽

D.R. Ward ◽

J.P. Kastelic

Keyword(s):

Ovarian Follicle ◽

Animal Health ◽

Beef Cows ◽

Estradiol Valerate ◽

Control Group ◽

Dominant Follicle ◽

Follicular Wave ◽

Follicle Diameter ◽

Growth Profiles ◽

Follicular Dynamics

The objective was to investigate the effect of dose of estradiol valerate (EV) on ovarian follicular growth profiles, intervals to follicular wave emergence and, following CIDR removal, estrus and ovulation in beef cows. On Day 0, 43 non-lactating, crossbred beef cows, 3 to 9 yr of age and at random stages of the estrous cycle, received a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and were randomly allocated to one of four groups to receive no further treatment (Control; n=10), or an injection of 1mg (n=11), 2mg (n=10), or 5mg (n=12) i.m. of EV (Sigma Chemical Co, St. Louis, MO, USA) in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined by transrectal ultrasonography once daily until 48h after CIDR removal to detect ovarian follicle growth profiles, and twice daily thereafter to detect ovulation. Data were analyzed by ANOVA (LSD and Bartlett’s tests) and chi-square procedures. One cow (5mg EV group) lost the CIDR and was removed from all analyses. There was an effect of day (P<0.0001) on CL diameter, but the effects of treatment (P=0.3), and the treatment-by-day interaction (P=0.1), were not significant. Follicular wave emergence occurred within 7d in 7/10 (70%) Control cows and 31/32 (97%; P<0.04) EV-treated cows (one cow in late diestrus at the time of treatment did not respond to 1mg EV). Mean (±SD) interval from treatment to wave emergence was longer (P<0.03) in cows treated with 5mg EV (4.8±1.2d) than in those treated with 1mg (3.2±0.9 days) or 2mg EV (3.4±0.8 days), while Control cows were intermediate (3.8±2.0 days). Although follicular wave emergence tended (P<0.09) to be more synchronous in cows receiving EV, intervals from CIDR removal to estrus (P=0.7) and ovulation (P=0.8) did not differ among groups. Diameter of the dominant follicle was smaller (P<0.04) at CIDR removal and tended to be smaller (P<0.08) just prior to ovulation in the 5mg EV group (8.5±2.2 and 13.2±0.6mm, respectively) than in the Control (11.8±4.6 and 15.5±2.9mm, respectively) or 1mg EV (11.7±2.5 and 15.1±2.2mm, respectively) groups, with the 2mg EV group (10.7±1.5 and 14.3±1.7mm, respectively) intermediate. Diameter of the dominant follicle at CIDR removal was less variable (P<0.01) in the 2 and 5mg EV groups than in the Control group and intermediate in the 1mg EV group. In summary, dose of EV affected follicular dynamics, interval to and synchrony of follicular wave emergence, and dominant follicle diameter at CIDR removal and just prior to ovulation in CIDR-treated cows. However, interval from CIDR removal to estrus and ovulation was not affected by treatment. Results suggest that a dose of 2mg EV may be most efficacious in synchronizing follicular wave emergence in CIDR-treated cows.

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The effect of GnRH or oestradiol injected at pro-oestrus on luteal function and follicular dynamics of the subsequent oestrous cycle in non-lactating cycling Holstein cows

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v73i1.170 ◽

2006 ◽

Vol 73 (1) ◽

Cited By ~ 1

Author(s):

B.V.E. Segwagwe ◽

K.L. MacMillan ◽

P.D. Mansell

Keyword(s):

Corpus Luteum ◽

Optimum Concentration ◽

New Wave ◽

Luteal Function ◽

Future Studies ◽

Induction Of Ovulation ◽

Follicular Wave ◽

Oestradiol Benzoate ◽

Lower Fertility ◽

Follicular Dynamics

Oestrous synchronization involves synchronization of ovarian follicular turnover, new wave emergence, and finally induction of ovulation. The final step can be synchronized by the parenteral administration of either GnRH or oestradiol benzoate. This study investigated corpus luteum and follicular emergence after ovulation had been induced by the administration of either GnRH or oestradiol benzoate. The injection of oestradiol benzoate may have delayed the emergence of the first follicular wave subsequent to the induced ovulation; administration of oestradiol benzoate or GnRH lowered the progesterone rise so that the maximum dioestrous concentration of progesterone on Day 9 was lower when cows were treated during pro-oestrus compared to the spontaneously ovulating controls. One implication of findings from the present study is that induction of ovulation with either oestradiol benzoate or GnRH, administered 24 or 36 h after withdrawal of the CIDR device, respectively, may lower fertility. Future studies must identify the timing of administration relative to the time of CIDR device withdrawal and the optimum concentration of oestradiol benzoate or GnRH that would not have untoward effects on the development of the corpus lutea, particularly within the first week of dioestrus.

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14OVARIAN FOLLICULAR DYNAMICS IN COWS TREATED WITH A CIDR, ESTRADIOL AND PROGESTERONE LATE IN THE ESTROUS CYCLE

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab14 ◽

2004 ◽

Vol 16 (2) ◽

pp. 129 ◽

Cited By ~ 7

Author(s):

J.P. Kastelic ◽

M.G. Colazo ◽

J.A. Small ◽

D.R. Ward ◽

R.J. Mapletoft

Keyword(s):

Estrous Cycle ◽

Ovarian Follicle ◽

Animal Health ◽

Beef Cows ◽

Control Group ◽

Dominant Follicle ◽

Chi Square ◽

Follicular Wave ◽

Follicle Diameter ◽

Follicular Dynamics

The objective was to characterize ovarian follicular dynamics in beef cows treated with a CIDR (Bioniche Animal Health; Belleville, Ontario, Canada) and an injection of estradiol-17β (E2), with or without progesterone (P4), late in the estrous cycle. Previously synchronized, non-lactating, crossbred beef cows (n=36) received a CIDR (Day 0) 16 to 18 days after ovulation and were randomly allocated to one of three treatment groups: no further treatment (Control, n=12), an injection of 5mg E2 (E2, n=12), or 5mg E2 plus 100mg P4 (E2P4, n=12; both from Sigma Chemical Co., St.Louis, MO, USA) i.m. in 2mL canola oil. On Day 7, CIDR were removed and cows received 500μg i.m. of cloprostenol (Estrumate, Schering Plough Animal Health, Pointe-Claire, Quebec, Canada). Ovaries were examined once daily by transrectal ultrasonography to detect ovarian follicle growth profiles, and determine the time of ovulation. Blood samples were taken daily for progesterone determination. Data were analyzed by ANOVA (LSD and Bartlett’s tests), Student’s t-test and chi-square procedures. Diameter of the CL and the dominant follicle, and progesterone concentration on Day 0 did not differ among groups (P=0.6; overall mean (±SD), 16.8±2.7mm, 14.1±2.0mm, and 1.5±1.9ngmL, respectively). Thirteen cows ovulated within 3 days of treatment (50% of E2- and E2P4-treated cows and 8.3% of Control cows; P=0.05); cows that ovulated had smaller CL diameters (15.2±1.7 v. 17.7±2.7mm; P<0.004) and lower progesterone concentrations (0.4±0.2 v.2.1±2.2ngmL; P<0.001) at the time of treatment. Follicular wave emergence occurred within 7 days in 4/12 Control cows, 10/12 E2-treated cows, and 10/12 E2P4-treated cows (P<0.01). Although the interval from treatment to wave emergence did not differ among treatments (P=0.8; overall, 3.4±1.5 days), follicular wave emergence was more synchronous (P<0.004) in the E2 group than in the Control or E2P4 groups. At CIDR removal, dominant follicle diameter was larger (P<0.02) in the Control group (15.9±5.5mm) than in the E2 (11.9±1.8mm) or E2P4 (11.5±3.4mm)groups, but dominant follicle diameter was less variable (P<0.003) in the E2 group than in the other two groups. Three cows did not ovulate after CIDR removal; two in the Control group and one in the E2P4 group. Interval to ovulation was shorter (P<0.05) in the Control group (70.8±10.5h)than in the E2 (87.0±9.0h) or E2P4 (86.2±7.2h) groups, and the intervals to ovulation in cows that ovulated following treatment (91.0±8.0h) was longer (P<0.001) than in those that did not (76.6±9.6h). In summary, treatment of cows with an estradiol-progesterone protocol late in the estrous cycle resulted in ovulation (50.0%), atresia (33.3%) or persistence (16.6%) of the dominant follicle present at that time. As length of follicular dominance and timing of ovulation were affected, fertility may be impaired following AI.

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