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

2002 ◽  
Vol 74 (3) ◽  
pp. 539-545 ◽  
Author(s):  
C. Viñoles ◽  
L. J. Harris ◽  
M. Forsberg ◽  
G. Banchero ◽  
E. Rubianes

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.

Reproduction ◽  
2010 ◽  
Vol 140 (6) ◽  
pp. 865-874 ◽  
Author(s):  
C Viñoles ◽  
B Paganoni ◽  
K M M Glover ◽  
J T B Milton ◽  
D Blache ◽  
...  

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.


2011 ◽  
Vol 23 (2) ◽  
pp. 303 ◽  
Author(s):  
Tanya E. Baby ◽  
Pawel M. Bartlewski

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.


2016 ◽  
Vol 21 (1) ◽  
pp. 26 ◽  
Author(s):  
Muhammad Imron ◽  
Iman Supriatna ◽  
. Amrozi ◽  
Mohamad Agus Setiadi

<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>


2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 469-469
Author(s):  
Junyou LI ◽  
Chunxiang Piao ◽  
Min Ma ◽  
Masayoshi Kuwahara

Abstract Ovarian follicular development was monitored daily by transrectal ultrasonographic examination in 20 female goats for 2 successive estrous cycles (40 cycles). These animals exhibited ovulatory cycles with a mean length of 20.8 ± 1.1 days. The mean number of follicles ovulated was 2.3 ± 0.9 and their diameter before ovulation was 6.9 ± 1.1 mm. Among 40 estrous cycles examined, 9 (23 %) displayed 1 latent follicular wave and the remaining 31 (77 %) cycles displayed 2 latent follicular waves. Three and 4 days after the second spontaneous ovulation (day 0 = ovulation), when diameter of dominant follicles of the first latent wave exceeded 5.5 mm, 20 goats were treated with a luteolytic dose of prostaglandin F2a (PGF2a) and randomly assigned to one of three groups. This treatment immediately decreased plasma levels of progesterone and increased those of estradiol, resulting in ovulation 2 or 3 days later. One group of goats (n = 5) treated with PGF2a at the first latent follicular wave and was mated with fertile male goat, resulting in 4 pregnancies. For the second group of goats (n = 5), 4 successive short estrous cycles were induced. A total of 35 short ovulatory cycles were induced at a mean interval of 6.5 ± 1.2 days with a range of 4–9 days. Five of goats were allowed to mate following 4 consecutive short ovulatory cycles; normal oestrous behavior was observed at each estrus. The goats were successfully mated, became pregnant and delivered kids of normal body weight and length. The remaining goats (n = 6), in addition to PGF2a treatment, received exogenous progesterone supplement which allowed latent follicular development to occur, but prevented ovulation until the effect of progesterone supplement subsided. Thus, it was concluded that appropriate phase of follicle size and progesterone concentration could control ovulation of ruminant animal.


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 ◽  
...  

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.


2012 ◽  
Vol 57 (No. 12) ◽  
pp. 562-572 ◽  
Author(s):  
R. Rajmon ◽  
J. Šichtař ◽  
L. Vostrý ◽  
D. Řehák

The indicators of follicle development with regard to the growth wave order, the first ovulation, animal parity, and also with regard to the simultaneous presence or absence of a follicular cyst were determined in cows in the course of 60 days postpartum. Follicular dynamics were monitored daily by ultrasonography. The animals were assigned to three groups based on the time of the 1<sup>st</sup> ovulation: G1 (n = 9) &ndash; the 1<sup>st</sup> dominant follicle (DF) ovulated, G2 (n = 10) &ndash; ovulation occurred on the 2<sup>nd</sup> or later follicular waves, and G3 (n = 5) &ndash; no ovulation occurred during the experimental period. G1 animals showed better fertility later (no cyst, less days open, P = 0.07, less hormonal treatment, P = 0.008). The rhythm of follicular wave development was generally similar in all the animals (based on emergence of the first follicular wave, the interval from emergence to deviation, and the number of all follicular waves). Nevertheless, emergence of follicular waves and deviation occurred by 0.5&ndash;0.9 day earlier in primiparous than in multiparous cows and in G1 vs. G2, or G3, respectively (in all P &lt; 0.05). DF development was independent of parity as well as group effects, but the maximum size and growth rate (1.2 vs. 0.8 cm/day, P &lt; 0.05) were higher in ovulatory follicles (OF) than in regressive ones (rDF). The presence of a growing cyst decreased the probability of rDF as well as OF development (P &lt; 0.0001). The OF growth rate was faster in the milieu of a stagnating cyst than without any cyst (P &lt; 0.04). Therefore, the development of follicles was dramatically suppressed beyond, but nor before, deviation in the milieu of a growing cyst. Cessation of the cyst growth accelerated the development of OFs. On the contrary, a cystic structure without any significant growth can persist for weeks with no effect on successful follicular development.


Reproduction ◽  
2000 ◽  
pp. 83-90 ◽  
Author(s):  
Z Roth ◽  
R Meidan ◽  
R Braw-Tal ◽  
D Wolfenson

The aim of this study was to characterize the immediate effects of heat stress on plasma FSH and inhibin concentrations, and its involvement in follicular dynamics during a complete oestrous cycle, and to examine a possible delayed effect of heat stress on follicular development. Holstein dairy cows were oestrous synchronized and randomly assigned to either cooled (n = 7) or heat-stressed (n = 6) treatment groups. During a complete oestrous cycle, control cows, which were cooled, maintained normothermia, whereas heat-stressed cows, which were exposed to direct solar radiation, developed hyperthermia. At the end of this oestrous cycle (treated cycle), both groups were cooled and maintained normothermia for the first 10 days of the subsequent oestrous cycle. Throughout this period, follicular development was examined by ultrasonography, and plasma samples were collected. During the second follicular wave of the treated oestrous cycle, a significantly larger cohort of medium sized follicles (6-9 mm) was found in heat-stressed cows than in cooled cows (P < 0.05). The enhanced growth of follicles in this wave in heat-stressed cows was associated with a higher plasma FSH increase which lasted 4 more days (days 8-13 of the oestrous cycle; P < 0.05), and coincided with a decrease in the plasma concentration of immunoreactive inhibin (days 5-18 of the oestrous cycle; P < 0.05). During the follicular phase (days 17-20 of the treated cycle), heat-stressed cows showed an increase in the number of large follicles (>/= 10 mm), and the preovulatory plasma FSH surge was significantly higher in heat-stressed cows than in cooled cows (P < 0.01). The effect of heat stress was also observed during the first follicular wave of the subsequent cycle: the postovulatory plasma FSH concentration was higher (P < 0.01), but fewer medium follicles developed, and the first follicular wave decreased at a slower rate in previously heat-stressed cows than in cooled cows (0.40 and 0.71 follicles per day, respectively). This study shows both immediate and delayed effects of heat stress on follicular dynamics, which were associated with high FSH and low inhibin concentrations in plasma. These alterations may have physiological significance that could be associated with low fertility of cattle during the summer and autumn.


1991 ◽  
Vol 3 (5) ◽  
pp. 529 ◽  
Author(s):  
H Kaneko ◽  
T Terada ◽  
K Taya ◽  
G Watanabe ◽  
S Sasamoto ◽  
...  

Changes in the plasma concentration of oestradiol-17 beta, progesterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were characterized during the transition from the luteal to the follicular phase, the periovulatory period and the early luteal phase in five cycling cows. The pattern of growth and the regression of follicles and corpora lutea in the ovary of the same animals were also assessed by daily ultrasonographic examinations. Two waves of follicular growth (ovulatory and non-ovulatory) occurred in all animals. The ovulatory follicular wave started from 4 days before the preovulatory surges of LH and FSH and the wave of next growth of a dominant follicle (non-ovulatory follicle) started within one day after ovulation. Changes in plasma levels of oestradiol-17 beta correlated well with the growth of both ovulatory and non-ovulatory dominant follicles. Suppression of FSH concentration during the follicular phase was inversely related to the increase in plasma concentration of oestradiol-17 beta. These results suggest that, in the cow, ovulatory dominant follicles suppress FSH secretion by increasing the concentration of oestradiol-17 beta (and probably also inhibin) during the follicular phase.


2021 ◽  
Vol 32 (1) ◽  
pp. e19504
Author(s):  
Uri Perez G. ◽  
David Pari P. ◽  
Fidel Gutierrez Y. ◽  
Julio Málaga A. ◽  
Natalio Luque M. ◽  
...  

La dinámica folicular ovárica monitoreada por vía transrectal (TR) y transvaginal (TV) en ondas sucesivas en llamas fue estudiada en 10 llamas con más de 4 años, multíparas, sin cría, estado corporal de 3.0, durante un periodo de 90 días en la época reproductiva. Se utilizó el ecógrafo Sonostar SS8® con un transductor lineal para el examen transrectal y transductor microconvexo endocavitario para el examen transvaginal, ambos con frecuencia de 6.5 MHz. El intervalo inter-onda fue de 20±4.4 y 22.5±5.3 por vía TR y TV, respectivamente; el número de folículos por cohorte fue 5.21±0.92 y 6.38±1.26 para TR y TV, respectivamente (p=0.0011); el diámetro máximo de folículos fue 12.49±3.57 mm para TR y 13.56±3.91 mm para TV; la tasa de crecimiento fue de 0.70±0.35 y 0.67±0.32 mm/día para TR y TV, respectivamente. La ecuación de regresión para relación del diámetro máximo folicular y duración de onda folicular vía TR fue de y=0.89766x+6.5554 (R²=0.423) y para la vía TV de y=0.8466x+10.184 (R²=0.479). La duración de las fases foliculares fue similar entre ambas técnicas con excepción de la fase de dominancia (10.2±3.19 días para TR y 8.67±2.46 para TV, p=0.0418). La relación entre el diámetro folicular y número de folículos detectados presentó una correlación negativa baja (R²=-0.0827 para TV y R²=-0.0876 para TR). En conclusión, el transductor endocavitario transvaginal permite determinar con mayor precisión las características de dinámica folicular en llamas en sus fases de reclutamiento, dominancia y regresión con sobreposición de ondas foliculares como característica importante.The ovarian follicular dynamics monitored by transrectal (TR) and transvaginal (TV) routes in successive waves was studied in 10 llamas older than 4 years, multiparous, without calves at foot, body condition of 3.0, during a period of 90 days in the reproductive season. The Sonostar SS8® ultrasound equipment was used with a linear transducer for transrectal examination and endocavitary microconvex transducer for transvaginal examination, both with a frequency of 6.5 MHz. The inter-wave interval was 20 ± 4.4 and 22.5 ± 5.3 via TR and VT, respectively; the number of follicles per cohort was 5.21 ± 0.92 and 6.38 ± 1.26 for TR and TV, respectively (p=0.0011); the maximum diameter of follicles was 12.49 ± 3.57 mm for TR and 13.56 ± 3.91 mm for TV; the growth rate was 0.70 ± 0.35 and 0.67 ± 0.32 mm/day for TR and TV, respectively. The regression equation for the ratio of the maximum follicular diameter and duration of follicular wave via TR was y=0.89766x+6.5554 (R²=0.423) and for the TV route y=0.8466x+10.184 (R²=0.479). The duration of the follicular phases was similar between both techniques except for the dominance phase (10.2±3.19 days for TR and 8.67±2.46 for TV, p=0.0418). The relationship between the follicular diameter and the number of follicles detected showed a low negative correlation (R²=-0.0827 for TV and R²=-0.0876 for TR). In conclusion, the transvaginal endocavitary transducer makes it possible to determine with greater precision the characteristics of llama follicular dynamics in their recruitment, dominance and regression phases with overlapping of follicular waves as an important characteristic.


2005 ◽  
Vol 10 (1) ◽  
Author(s):  
L.E. KOZICKI ◽  
M.S. SEGUI ◽  
J.C. FANTINI FILHO ◽  
F.R.A. PRADO ◽  
F. MATTÉ ◽  
...  

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).


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