scholarly journals Follicular wave emergence in Santa Inês ewes subjected to long-term, progesterone-based estrous synchronization protocols at different times of the year

2016 ◽  
Vol 174 ◽  
pp. 80-86 ◽  
Author(s):  
M.E.F. Oliveira ◽  
H. Ayres ◽  
L.G. Oliveira ◽  
E. Oba ◽  
R.T. Kridli ◽  
...  
Keyword(s):  
Estrous Synchronization ◽  
Follicular Wave ◽  
Santa Inês

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

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.

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

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.

418 EFFECT OF SUPEROVULATION INITIATED AT FOLLICULAR WAVE EMERGENCE IN Santa Inês EWES

2010 ◽  
Vol 22 (1) ◽  
pp. 366
Author(s):  
B. D. M. Silva ◽  
T. A. S. N. Silva ◽  
L. Dalcin ◽  
C. M. Lucci ◽  
J. P. Neves
Keyword(s):  
Total Dose ◽  
Buenos Aires ◽  
Ovarian Response ◽  
Corpora Lutea ◽  
Dominant Follicle ◽  
Treatment Groups ◽  
Follicular Wave ◽  
Preliminary Study ◽  
Santa Inês ◽  
Fresh Semen

Superovulation in ewes has been a source of many studies aimed at obtaining high superovulatory response and number of viable embryos recovered. In a protocol called Day 0, superovulatory treatment was initiated at the time of wave emergence in the absence of a dominant follicle (Menchaca A et al. 2002 Theriogenology 58, 1713-1721). The aim of this study was to compare ovarian response and number of embryos recovered after treatment between ewes treated with a Day 0 protocol and those treated with a traditional protocol. Santa InÊs ewes (n= 18) between 2 and 5 years old were randomly distributed into 2 superovulation treatment groups: traditional protocol and Day 0 protocol. Each treatment was repeated twice in a crossover model. The traditional protocol consisted of the intravaginal insertion of a sponge containing 60 mg of medroxiprogesterone acetate (MAP; Progespon®, Tecnopec, São Paulo, Brazil) for 14 days, which was replaced on Day 7, followed by 150 μg of cloprostenol (Prolise®, Tecnopec) i.m. On Day 12, FSH (Folltropin®-V, Bioniche, Belleville, Ontario, Canada) treatment was initiated using a total dose of 200 mg, given in twice-daily i.m. injections that decreased in dose over 4 days. A dose of 200 IU of eCG (Novormon®, Syntex, Buenos Aires, Argentina) i.m. was given at the time of sponge withdrawal. The AI was done by laparoscopy at 48 and 55 h after sponge withdrawal using fresh semen. The Day 0 protocol consisted of a previous 9-day synchronization treatment with a sponge containing 60 mg of MAP, followed by 150 μ of cloprostenol i.m. and 200 IU of eCG i.m. given on Day 7. A dose of 0.05 mg of GnRH (lecirelin; Gestran Plus®, Tecnopec) i.m. was given 16 h after sponge withdrawal. In a preliminary study, 38 ewes ovulated 42 ± 52 h after sponge withdrawal. Therefore, 48 h after sponge removal was considered as Day 0 and FSH treatment was initiated at that time, with a total dose of 200 mg of Folltropin®-V, given in 6 twice-daily decreasing doses. Two doses of cloprostenol (150 μg) were given i.m. concurrent with the fifth and sixth FSH treatments. Gonadotropin-releasing hormone (0.05 mg of lecirelin i.m.) was given 12 h after the last FSH treatment. Artificial insemination with fresh semen was done by laparoscopy 16 and 26 h after GnRH treatment. Five days after AI, embryos were recovered surgically. Results were evaluated by the parametric t-test. The number of corpora lutea and ova/embryos recovered did not differ (P > 0.05) between the traditional (9.8 ± 5.3; 4.5 ± 4.6) and Day 0 (10.0 ± 6.0; 3.5 ± 4.3) protocols. Similarly, no difference in the number of viable embryos was observed between treatments (1.6 ± 2.0 and 1.7 ± 2.4 for the traditional and Day 0 treatments, respectively). Within viable embryos, the traditional protocol (0.4 ± 1.0) resulted in ahigher (P < 0.05) number of morulae than that of the Day 0 protocol (0.1 ± 0.3). The ewes that had no superovulatory response did not differ (P > 0.05) between the traditional (11.11%) and Day 0 (5.56%) protocols. In summary, there was no difference in the parameters evaluated between both protocols. Financial support: FAPDF, CNPq, Tecnopec.

scholarly journals 317 EFFECT OF TIME OF ONSET OF FOLLICLE-STIMULATING HORMONE TREATMENT ON SUPEROVULATORY RESPONSE AND EMBRYO YIELD OF SANTA INES EWES DURING BREEDING SEASON

2013 ◽  
Vol 25 (1) ◽  
pp. 306
Author(s):  
M. E. F. Oliveira ◽  
C. C. D'Amato ◽  
C. S. Oliveira ◽  
F. F. P. C. Barros ◽  
A. P. Perini ◽  
...  
Keyword(s):  
New York ◽  
Breeding Season ◽  
Animal Health ◽  
Hormone Treatment ◽  
Corpora Lutea ◽  
Mating Period ◽  
Follicular Wave ◽  
Embryo Yield ◽  
Pfizer Animal Health ◽  
Santa Inês

This study was designed to investigate if the time of onset of FSH treatment [near the emergence of first or last follicular wave on progesterone (P4) protocol] influenced the superovulatory response and embryo yield in Santa Ines ewes during breeding season. Days of emergence of the follicular waves were defined in a previous study that evaluated the follicular dynamic in oestrus synchronization treatments (Oliveira et al. 2011 Acta Sci. Vet. 40). We observed emergence of the first and last follicular wave on 5.69 ± 0.42 and 11.25 ± 0.39 days of protocol, respectively. Twenty Santa Ines ewes were submitted to 2 superovulatory protocols according to the time that FSH treatments were initiated (G-first wave, n = 10; G-last wave, n = 10). On Day 0, all ewes received a P4 device (CIDR®; Pfizer Animal Health, New York, NY, USA) and injection of 37.5 µg of d-cloprostenol, IM. The FSH treatments started on Day 6 and Day 11 of protocol for G-first and G-last, respectively. The superovulatory regimen consisted of 8 IM injections of pFSH administrated twice daily (40, 40, 30, 30, 20, 20, 10, and 10 mg of pFSH). The P4 device was removed on Day 8 and Day 13 for G-first and G-last, respectively. At these times, all ewes received another injection of 37.5 µg of d-cloprostenol and a dose of 200 IU of eCG. During 4 days after the P4 device removal, ewes were mated by a fertile ram. Embryo collections were accomplished 7 days after CIDR withdrawal. The ovaries were evaluated by ultrasonography (3 times daily, during the mating period) and laparotomy (concomitantly with embryo collection). The superovulatory response was observed by classified by score: 0 = 4 or fewer corpora lutea (CL); 1 = between 5 and 10 CL; and 2 = 11 or more CL. Data were analysed by GLIMMIX using SAS software (SAS Institute Inc., Cary, NC, USA). All donors from G-first had superovulatory response classified as score 2, whereas 60% of ewes from G-last were classified as score 2, 20% as score 1, and 20% as score 0 (P < 0.05). There were effects between treatments (P < 0.05) for ovulation rate (G-first: 97.9 ± 1.4% v. G-last: 88.5 ± 4.4%) and number of ovulations (G-first: 17.0 ± 2.3 v. G-last: 12.5 ± 2.6). The numbers of luteinized unovulated follicles were 0.7 ± 0.5 for G-first and 1.2 ± 0.4 for G-last (P > 0.05). There was no difference between G-first and G-last (P > 0.05) in the rate of ova/embryos recovered (54.9 ± 5.7% v. 49.3 ± 8.5%), mean number of ova/embryos recovered (9.0 ± 1.4 v. 6.3 ± 1.1), number of viable embryos (3.8 ± 1.5 v. 3.4 ± 0.8), or viability rate (40.3 ± 10.8 v. 53.4 ± 12.1). In conclusion, the FSH treatment started near the emergence of the first follicular wave of progesterone protocol in Santa Ines ewes during the breeding season resulted in a higher superovulatory response than that started near the last follicular wave; however, no improvements in embryo yield were observed. Financial support: FAPESP.

scholarly journals 213 USE OF ACTIVE CASPASE 3 AND TUNEL ASSAYS TO ESTIMATE EMBRYONIC QUALITY IN IN VIVO SANTA INES EWE EMBRYOS

2014 ◽  
Vol 26 (1) ◽  
pp. 220 ◽  
Author(s):  
M. E. F. Oliveira ◽  
C. S. Oliveira ◽  
M. R. Lima ◽  
F. F. P. C. Barros ◽  
A. P. Perini ◽  
...  
Keyword(s):  
Breeding Season ◽  
Caspase 3 ◽  
Transition Period ◽  
Pearson Correlation ◽  
Apoptotic Cells ◽  
Nonbreeding Season ◽  
Follicular Wave ◽  
Santa Inês ◽  
Active Caspase

This study was designed to quantify the percentage of apoptotic cells using active caspase 3 and TUNEL assays, in order to estimate the quality of ovine embryos produced in vivo. For that, 60 Santa Ines ewes (n = 10 per group) were submitted to superovulation with FSH treatment started near the different follicular wave emergence of the protocols (G-1 or G-2), during breeding season, transition, and nonbreeding season. Follicular wave emergence days were defined in a previous study that evaluated the follicular dynamic in oestrus synchronization treatments (Oliveira et al. 2011 Acta Sci. Vet. 38, 361). On Day 0, all ewes received a P4 device (CIDR®) and 37.5 μg of D-cloprostenol. The P4 device was replaced by a new one on Day 7 just for G-2 in the transition period. The superovulation treatment started on Day 4, 4, and 6 of protocol for G-1 and on Day 10, 10, and 11 for G-2 in nonbreeding, transition, and breeding season, respectively. The FSH treatment consisted of eight injections of pFSH administrated twice a day in descending order (40, 30, 20, and 10 mg of pFSH). The P4 device was removed two days after beginning of FSH treatment. At these times, all ewes received another injection of 37.5 μg of D-cloprostenol and a dose of 200 IU of eCG. Ewes were mated with a fertile ram for 4 days after P4 device removal. Embryo recoveries were carried out by laparotomy, 7 days after CIDR withdrawal. Embryos were morphologically classified. Grade I to III morulas and blastocysts were considered viable. A representative sample of each treatment was fixed and stained by active caspase 3 and TUNEL assays to assess the apoptotic cells percentage. Data were analysed by GLIMMIX using SAS comparing mean values (±s.e.m.) between groups at each season (P = 0.05). Pearson correlation was estimated between active caspase 3 and TUNEL assays. No effect was detected between treatments in each season on the number of viable embryos (3.2 ± 0.8 v. 1.8 ± 0.8, 3.9 ± 1.9 v. 5.7 ± 1.4, and 3.8 ± 1.5 v. 3.4 ± 0.8 for G-1 v. G-2 in nonbreeding, transition and breeding season, respectively). The treatment G-2 increased (P < 0.05) apoptotic cells percentage in nonbreeding season group, assessed by active caspase 3 (G-1: 3.1 ± 1.6% and G-2: 12.8 ± 4.3%) and TUNEL (G-1: 1.6 ± 0.5% and G-2: 11.1 ± 3.5%) assays. The apoptotic cells percentage remained unaltered for Transition and Breeding season groups, assessed by either active caspase 3 (G-1: 6.0 ± 0.9% and 5.6 ± 1.5%; G-2: 5.6 ± 1.1% and 5.1 ± 0.5%) and by TUNEL (G-1: 7.5 ± 1.3% and 5.2 ± 1.0%; G-2: 5.0 ± 0.9% and 6.4 ± 1.1%). The Pearson correlation between active caspase 3 and TUNEL tests was r2 = 0.436 (P < 0.0001). In conclusion, the active caspase 3 and TUNEL assays presented similar results for apoptosis level assessment in Santa Ines ewes in vivo produced embryos, and both assays were considered appropriate for this purpose. The increased apoptosis levels detected in the G-2 nonbreeding season group suggest that this treatment is harmful for Santa Ines ewe embryos. Financial support was provided by FAPESP and FUNDUNESP.

scholarly journals Effect of different protocols for estrus synchronization on reproductive performance of Santa Inês ewes under Amazon environmental conditions

2020 ◽  
Vol 43 ◽  
pp. e48954
Author(s):  
Regina Oliveira da Silva ◽  
Roseane Pinto Martins de Oliveira ◽  
André Ferreira Silva ◽  
Franklyn Ferreira de Oliveira ◽  
João Paulo Ferreira Rufino ◽  
...  
Keyword(s):  
Experimental Design ◽  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Environmental Conditions ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Test Results ◽  
Short Term ◽  
Santa Inês

 The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukey’s test. Results were considered significant at p ≤ 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.

Effect of reproductive methods and GnRH administration on long-term protocol in Santa Ines ewes

2017 ◽  
Vol 49 (6) ◽  
pp. 1303-1308 ◽  
Author(s):  
Marcos V Biehl ◽  
Marcos V C Ferraz Junior ◽  
Evandro M Ferreira ◽  
Daniel M Polizel ◽  
Alexandre A Miszura ◽  
...  
Keyword(s):  
Santa Inês

Long-term chromium picolinate supplementation improves colostrum profile of Santa Ines ewe

2019 ◽  
Vol 193 (2) ◽  
pp. 414-421
Author(s):  
Thiago F. V. Bompadre ◽  
Débora B. Moretti ◽  
Gabriel Z. Sakita ◽  
Egon H. Ieda ◽  
Maria I. V. Martinez ◽  
...  
Keyword(s):  
Chromium Picolinate ◽  
Santa Inês

353 FOLLICULAR POPULATION STATUS AT THE FIRST FOLLICLE-STIMULATING HORMONE INJECTION IN EWES SUPERSTIMULATED NEAR THE FIRST FOLLICULAR WAVE OF CIDR PROTOCOL

2015 ◽  
Vol 27 (1) ◽  
pp. 264
Author(s):  
M. E. F. Oliveira ◽  
M. A. R. Feliciano ◽  
L. G. Oliveira ◽  
J. F. Fonseca ◽  
W. R. R. Vicente
Keyword(s):  
Pearson Correlation ◽  
Follicle Stimulating Hormone ◽  
Large Population ◽  
Population Status ◽  
Mean Values ◽  
Follicular Wave ◽  
Hormone Injection ◽  
Phase Data ◽  
Santa Inês ◽  
Stimulating Hormone

This study was designed to evaluate the follicular status at the 1st FSH injection in ewes superstimulated near the 1st follicular wave of the CIDR protocol during nonbreeding (NB), transition (T), and breeding (B) season, and thus to correlate them with the superovulatory response (SR). On Day 0, all females (30 Santa Ines ewes; n = 10 per season) received a progesterone (P4) device (CIDR®; Zoetis, Brazil) and 37.5 µg of d-cloprostenol. The superestimulation (ST) was initiated on Day 4, 4, and 6 of protocol in the NB, T, and B season, respectively. These follicular wave emergence days were defined in a previous study that evaluated the follicular dynamic in P4 protocol (Oliveira et al. 2011 Acta Scientiae Veterinariae, 38, 361). The ST consisted of 8 injections of pFSH administrated twice a day in descending order (40/30/20/ and 10 mg of pFSH; Folltropin-V, Bioniche, Canada). The P4 device was removed 2 days after the beginning of the FSH treatment and all ewes received another injection of 37.5 µg of d-cloprostenol and a dose of 200 IU of eCG at the same time. B-mode ultrasound of ovaries was performed immediately before the 1st FSH injection. The follicles were classified according to their diameters into categories based on physiological dynamics: (C1) 2–4.25 mm, representative of the population before dominance phase; (C2) 4.5–5 mm, initial dominance phase; (C3) 5.25–5.75 mm, middle dominance phase; and (C4) 6 mm, preovulatory phase. Data were analysed by GLIMMIX using SAS comparing mean values (± s.e.m.) between seasons (P < 0.05) and Pearson correlation was made. All ewes had small follicles (C1) at the beginning the ST; however, only one female had solely C1 follicles. The number of C1 follicles did not differ between seasons (12.9 ± 0.9, 12.8 ± 0.8, and 12.1 ± 0.5 follicles for the NB, T, and B season, respectively). One-half of the animals from NB and T seasons had no C3 and C4 follicles, whereas 40% of females in B season showed the same follicular status. The percentage of ewes that had no C4 follicles was 80, 100, and 50% for the NB, T, and B season, respectively. There were no difference between season in number of C2 follicles (1.8 ± 0.5, 1.7 ± 0.4, and 1.7 ± 0.4) and C3 follicles (0.3 ± 0.1, 0.6 ± 0.2, 0.1 ± 0.1) for NB, T, and B seasons, respectively. However, the number of C4 follicles was significantly higher (P < 0.05) in the NB (0.2 ± 0.13) and B (0.6 ± 0.2) season than T period, which had no follicles in this category. The SR did not differ between seasons (12.4 ± 0.9, 13.1 ± 2.3, and 17.0 ± 2.3 for the NB, T, and B season, respectively) and had no correlation to any follicular category. In conclusion, the ST started on a day when there was a large population of small follicles, regardless of the season, confirming proximity to follicular wave emergence. However, the ovarian population was not restricted to this category. Therefore, it is possible that wave emergence has already started in some ewes before the initiation of the ST.Financial support is from FAPESP and CNPq.

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