scholarly journals 228DOMINANT FOLLICLE DEVIATION IN GUZERA BREED (BOS INDICUS) COWS

2004 ◽  
Vol 16 (2) ◽  
pp. 235
Author(s):  
J.H.M. Viana ◽  
G.T.R.M. Coutinho ◽  
M.P. Palhao ◽  
L.S.A. Camargo ◽  
W.F. Sa ◽  
...  
Keyword(s):  
Bos Indicus ◽  
Maximum Diameter ◽  
Zebu Cattle ◽  
Dominant Follicle ◽  
Estrous Cycles ◽  
Portable Ultrasound ◽  
Follicular Wave ◽  
Lower Maximum ◽  
Ovulatory Follicles ◽  
Follicular Dynamics

Follicular dynamics of Zebu Cattle are characterized by lower maximum diameter and persistence of dominant follicles, when compared to European breeds. However, the main effects of follicular dominance on subordinated follicle population, and consequently on oocyte recovery and embryo production, have been shown to be similar among breeds. The aim of this study was to evaluate the dominant follicle establishment period, indicated by follicle divergence, in Zebu cows. Pluriparous, non-lactating Guzera breed (Bos indicus) cows (n=5), presenting a mean body weight of 518.0±48.5kg and similar body score condition (ranging from 3.5 to 4, in a 1 to 5 scale), were used. In a first trial, follicular dynamics were evaluated daily during 1 (n=2) or 2 (n=3) estrous cycles, using a portable ultrasound device equipped with a linear rectal 5MHz transducer (Aloka SSD500, Aloka Co., Tokyo, Japan). In a second trial, estrous cycles were synchronized using progesterone intravaginal-releasing devices (CIDR, Pharmacia, Sao Paulo, Brazil), and follicular dynamics were evaluated every 6h after ovulation, during the first follicular wave, until the largest follicle achieved a diameter of 10mm. During each evaluation ovaries were mapped, and evolution of follicles followed individually. Data are normalized for the moment of follicular divergence, and analyzed by ANOVA. Results are presented as mean±SD. Data from the first evaluations confirmed the occurrence of cycles with three (4/8) and four (1/8) follicular waves, despite a mean cycle length of 19.1±1.9 days, with a maximum diameter of 11.6±2.4mm for non-ovulatory follicles, and 14.4±0.5mm for ovulatory follicles. Follicular deviation during the first follicular wave occurred 49.2±5.0h after ovulation, when the largest follicle presented a diameter of 7.3±0.6mm, and the second largest follicle 6.8±0.7mm. Growth rates of the dominant and the largest subordinated follicles were similar before (0.35mm/6h vs. 0.33mm/6h, respectively;; P>0.05), but significantly different after deviation (0.52mm 6h v. −0.04mm 6h; P<0.05). These results shows that the lower maximum diameter and persistence of dominant follicles, in Zebu cattle, is partially compensated by an earlier dominant follicle deviation.

scholarly journals Follicular dynamics in zebu cattle

2000 ◽  
Vol 35 (12) ◽  
pp. 2501-2509 ◽  
Author(s):  
JOÃO HENRIQUE MOREIRA VIANA ◽  
ADEMIR DE MORAES FERREIRA ◽  
WANDERLEI FERREIRA DE SÁ ◽  
LUIZ SÉRGIO DE ALMEIDA CAMARGO
Keyword(s):  
Estrous Cycle ◽  
Bos Indicus ◽  
Maximum Diameter ◽  
Zebu Cattle ◽  
Dominant Follicle ◽  
Serum Progesterone ◽  
Portable Ultrasound ◽  
Follicular Waves ◽  
Ovulatory Follicle ◽  
Follicular Dynamics

The aim of this study was to investigate the follicular dynamics during estrous cycle in Gir breed (Bos indicus) cows. Follicular growth and atresia during estrous cycle were evaluated using a portable ultrasound device. Luteal activity was evaluated by serum progesterone levels. Cycles with two (6.67%), three (60.00%), four (26.67%) and five (6.67%) follicular waves were observed. There was no difference (P>0.05) in dominant or subordinate follicles growth or atresia rates among follicular waves. The maximum diameter of the ovulatory follicle was higher than the diameter of the other dominant follicles in cycles with four waves, and higher than the diameter of the second dominant follicle in cycles with three waves (P<0.05). There was no difference (P>0.05) in estrous cycle length (21.11±1.76 and 22.25±1.71 days) or progesterone levels during diestrous (4.48±1.45 and 5.08±1.40 ng/mL) between cycles with three or four waves. Follicular dynamics in Gir cattle is characterized by a higher incidence of cycles with three or four waves, associated with a low persistence of the dominant follicle.

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

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
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.

Studies on Ovarian Follicular Dynamics and Steroid Profiles in Sahiwal Cattle

2021 ◽  
Author(s):  
Vinny Dodiyar ◽  
Parkash Singh Brar ◽  
Narinder Singh ◽  
Mrigank Honparkhe
Keyword(s):  
Corpus Luteum ◽  
Estrous Cycle ◽  
Maximum Diameter ◽  
Endocrine Regulation ◽  
Dominant Follicle ◽  
Estrous Cycles ◽  
Significant Difference ◽  
Sahiwal Cattle ◽  
Sahiwal Cows ◽  
Follicular Dynamics

Background: Understanding of ovarian follicular dynamics and endocrine regulation is essential to design and use interventions to optimize reproductive efficiency. Bos indicus and Bos taurus cows have some differences in their follicular dynamics and ovarian steroidal hormones. The present study was planned to understand follicular dynamics vis-a-vis ovarian steroids profiles in Sahiwal cattle. Methods: The study was conducted in normal cyclic, pluriparous, non-lactating Sahiwal cows (n=7). Trans-rectal ultrasonography was performed to record the location, size, number of follicles and size of corpus luteum (CL) from the beginning, till the end of experiment. The dataset was used to characterize the follicular wave emergence, growth, regression, time of selection and ovulation of the dominant follicle in each cow. Result: Three Sahiwal cows showed two wave and four cows showed three wave estrous cycles with mean interovulatory length of 20.33±0.33 and 22.50±0.28 days, respectively. No significant difference was recorded in the maximum diameter of corpus luteum, P4 and E2 plasma levels between 2-wave and 3-wave estrous cycles. The peak progesterone values of 6.00±0.91 and 6.2±1.2 ng/ml and peak estradiol values of 15.83±0.60 and 14.31±0.44 ng/ml were recorded in 2-wave and 3-wave estrous cycle, respectively. The results showed that Sahiwal cows had 2-wave and 3-wave estrous cycle and the 3-wave estrous cycle had comparatively longer inter-ovulatory period and smaller maximum diameter of second wave dominant follicle than 2-wave estrous cycle.

Effect of the dominant follicle on regression of its subordinates in heifers

1993 ◽  
Vol 73 (2) ◽  
pp. 267-275 ◽  
Author(s):  
G. P. Adams ◽  
K. Kot ◽  
C. A. Smith ◽  
O. J. Ginther
Keyword(s):  
Key Words ◽  
Maximum Diameter ◽  
Sham Operation ◽  
Dominant Follicle ◽  
Follicular Waves ◽  
Follicular Wave ◽  
The Relationship ◽  
Small Follicle

The relationship between a dominant follicle of a follicular wave and the suppression of subordinate follicles was studied during the first postovulatory wave (Wave 1) in Holstein heifers. The dominant follicle (largest follicle) was cauterized or a sham-operation was done on day 3 (day 0 = ovulation) using seven heifers per group. In the cautery group, compared to the controls, the largest subordinate follicle attained a larger diameter (11 7 vs 8 0 mm; P < 0.01), reached maximum diameter at a later day (day 9.2 vs. day 3.1; P < 0 01) and began to regress at a later day (day 14.3 vs. day 5.7; P < 0.01). In addition, the emergence of Wave 2 was hastened (day 6.4 vs. day 9.3; P < 0.05) and more heifers had more than two waves per interovulatory interval (5 of 6 vs. 2 of 7; P < 0.05). In heifers with the dominant follicle eliminated, the largest subordinate grew to the diameter of a dominant follicle during Wave 1 (n = 3) or became the dominant follicle of a newly emerged wave (n = 2). A subordinate sometimes persisted as a small follicle (e.g., 5 mm) for several days before resurging. However, it was not convincingly demonstrated that a subordinate follicle could resurge after it had begun to regress (decrease in diameter). Results supported the hypothesis that suppression of subordinate follicles is a prolonged process, so that resurgence of a subordinate can occur if the dominant follicle is removed. Key words: Ovaries, follicular waves, selection, cattle, cauterization

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

2016 ◽  
Vol 21 (1) ◽  
pp. 26 ◽  
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>

208 OVARIAN FOLLICULAR DYNAMICS IN SOUTH AMERICAN CAMELIDS: EFFECT OF PLANE OF NUTRITION AND SPECIES

2010 ◽  
Vol 22 (1) ◽  
pp. 262
Author(s):  
M. P. Cervantes ◽  
T. Orban ◽  
G. P. Adams
Keyword(s):  
Body Condition ◽  
Suppressive Effect ◽  
Maximum Diameter ◽  
Dominant Follicle ◽  
Observational Period ◽  
Engineering Research ◽  
South American Camelids ◽  
Nutritional Conditions ◽  
Main Effects ◽  
Follicular Dynamics

Controversy exists regarding characteristics of follicular waves in llamas and alpacas. Lactational status has been shown to influence follicular dynamics, but the effects of species and nutrition have not been critically examined. A 2 × 2 experimental design was used to determine the effects of species (llama v. alpaca) and nutritional status (high-plane v. low-plane) on ovarian follicular wave dynamics. Adult female llamas (n = 16) and alpacas (n = 19), ≥ 3 years old, were assigned randomly to either a high or low plane of nutrition. Nutritional planes were defined by the grazing condition of the native pasture. The respective nutritional conditions were imposed 2 weeks before the start of the observational period. Body condition was estimated at the start of the observational period using a subjective scoring system (1 = very thin, 10 = very fat) and ovarian dynamics were monitored daily by transrectal ultrasonography for 38 days. Data were analyzed by two-way ANOVA and are expressed as mean ± SEM. Body condition scores were not different among groups (6.9 ± 0.35 and 6.6 ± 0.19 for llamas on high and low planes of nutrition, respectively, and 7.2 ± 0.25 and 6.8 ± 0.18 for alpacas on high and low planes of nutrition, respectively). The growing phase of the dominant follicle tended (P = 0.1) to be longer in llamas than in alpacas (9.8 ± 0.47 v. 8.8 ± 0.45 days) and in animals on a high plane of nutrition than in animals on a low plane (9.6 ± 0.50 v. 8.6 ± 0.42 days). Accordingly, the maximum diameter of the dominant follicle tended to be larger in llamas than in alpacas (10.1 ± 0.37 v. 9.1 ± 0.30 mm; P = 0.06) and in animals on a high plane of nutrition than in animals on a low plane (9.9 ± 0.39 v. 9.1 ± 0.27 mm; P = 0.14). The interwave interval was similar between llamas and alpacas (16.5 ± 0.66 v. 15.6 ± 0.42 days; P = 0.29), but was longer (P < 0.01) in animals on a high plane of nutrition than in animals on a low plane (16.9 ± 0.54 v. 15.0 ± 0.44 days); there was no interaction between main effects (P = 0.31). The total lifespan (duration of detection) of the dominant follicle was similar in both llamas and alpacas (22.9 ± 0.75 v. 21.9 ± 0.73 days; P = 0.38) and in animals on a high plane of nutrition than in animals on a low plane (22.7 ± 0.78 v. 22.0 ± 0.70 days; P = 0.53). There was no interaction between main effects (P = 0.21). All females (n = 35/35, 100%) had a follicle ≥ 7 mm (ovulatory size) from Days 7 to 12 after wave emergence. In conclusion, a low plane of nutrition had a suppressive effect on dominant follicle growth, resulting in a shortened interwave interval in llamas and alpacas. The interwave interval was not significantly longer in llamas than in alpacas despite a tendency for a longer growing phase and a larger dominant follicle. Research supported by Mitchell Group’s Mallkini Alpaca Breeding and Genetic Centre and the Natural Sciences and Engineering Research Council of Canada.

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

2004 ◽  
Vol 16 (2) ◽  
pp. 130 ◽  
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&lt;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&lt;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&lt;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&lt;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&lt;0.04) at CIDR removal and tended to be smaller (P&lt;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&lt;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.

scholarly journals Ovarian follicular dynamics in Boran and Crossbred heifers in Ethiopia: Implications for assisted reproductive techniques

2020 ◽  
Vol 24 (2) ◽  
pp. 54-72
Author(s):  
Jeilu Jemal ◽  
Tamrat Degefa ◽  
Tefera Yilma ◽  
Sayid Ali ◽  
Lemma Alemayehu
Keyword(s):  
Recovery Rate ◽  
Ovarian Follicle ◽  
Reproductive Potential ◽  
Progesterone Level ◽  
Maximum Diameter ◽  
Serum Progesterone ◽  
Estrous Cycles ◽  
Follicular Waves ◽  
Follicular Dynamics

The study was conducted to characterize the follicular dynamics of purebred Boran (Bos indicus) and Boran * Holstein Friesian crossbred heifers  during estrous cycles; for use in ovum pick up and in-vitro embryo production. Insight of reproductive physiology of cattle would help to understand and exploit the reproductive potential of elite animals for breed improvement. Follicular development, growth and atresia during estrous cycles were evaluated using a trans-rectal real-time B-mode ultrasound system for three consecutive estrus cycles. Luteal activity was evaluated by serum progesterone level. Follicular aspirations were done to investigate the potential of Boran cattle and their crosses for transvaginal oocyte production; using a vacuum pressure pump and Aloka SSD Prosound-2 ultrasound device. Boran heifers (n=15) manifested two (n = 6, 40%), three (n = 5, 33%), four (n= 3, 20%) and five (n=1, 6.7%) follicular waves. Crossbred heifers (n=14) showed one (n= 2, 14%), two (n= 6, 43%) and three (n= 6, 43%) follicular waves. Interovulatory interval was 21.1 ± 3.4 and 21.4 ± 2.7 days for Boran (n=45) and crossbred (n=42) heifers, respectively. The progesterone level in Boran and Crossbred heifers during diestrus was 9.5 ± 11.0 and 4.6 ± 8.8 ng/ml, respectively. The maximum diameter of the ovulatory follicle for crossbred heifers was higher (15.4 ± 1.6 mm) than the diameter of the Boran (14.0 ± 1.9 mm) heifers (p<0.005). Differences (p<0.005) were observed in the size of both right (26.6 ± 5.14 and 28.6 ± 5.1 mm) and left (21.7 ± 4.85 and 24.1 ± 5.07 mm) ovaries of Boran and Crossbred heifers, respectively. Difference (p<0.005) was also observed in follicular count of the  right ovaries of Boran (4.84 ± 1.96) and Crossbred  (5.13 ± 2.05) heifers. Oocyte recovery rate in once weekly collection scheme for Boran and their crossbred heifers was (n=19, 42.08%) and (n=17, 42.55%), respectively. The recovery rate for twice weekly collection scheme was (n=24, 34.53%) and (n=23, 40.44%) for Boran and crossbred heifers, respectively. Follicular dynamics in Boran heifers is characterized by a higher incidence of cycles with two, three and four waves, associated with a low persistence of the dominant follicles; and smaller size of ovulatory follicles and less intense heat signs from their crossbred counterpart. Boran heifers proved to have potential for comparable number of follicular population and ease of aspiration procedures that can be tapped for advancedreproductive techniques. Keywords: Estrus cycle; follicular wave; ovarian follicle; ovum pickup; ultrasound.

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

2004 ◽  
Vol 16 (2) ◽  
pp. 129 ◽  
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&lt;0.004) and lower progesterone concentrations (0.4±0.2 v.2.1±2.2ngmL; P&lt;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&lt;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&lt;0.004) in the E2 group than in the Control or E2P4 groups. At CIDR removal, dominant follicle diameter was larger (P&lt;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&lt;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&lt;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&lt;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.

224 OVARIAN FOLLICLE DEVELOPMENT DURING SEASONAL TRANSITION IN WAPITI

2006 ◽  
Vol 18 (2) ◽  
pp. 220
Author(s):  
R. McCorkell ◽  
M. Woodbury ◽  
G. Adams
Keyword(s):  
Breeding Season ◽  
Ovarian Follicle ◽  
Follicular Development ◽  
Maximum Diameter ◽  
Follicle Development ◽  
Estrous Cycles ◽  
Ovarian Follicle Development ◽  
Array Transducer ◽  
October 17 ◽  
Ovulatory Follicles

Wapiti are seasonally polyestrous. The transition into and out of the breeding season is marked by resumption of ovulation in autumn and cessation of ovulation in winter. Onset of ovulatory cyclicity is distinct and associated with aggressive breeding behavior of stags in rut. Cessation of ovulation at the end of the breeding season is not distinguished by behavioral patterns. The objective of the present study was to characterize follicular and luteal dynamics in wapiti during the transitional periods into and out of the breeding seasons. Transition from anestrus to estrus was monitored in 15 hinds, aged 2 to 14 years, over two successive seasons (11 in year 1, with 5 hinds from year 1 used again in year 2 along with 4 new hinds; n = 20 observations). Transition from estrus to anestrus was monitored in 11 hinds over 1 season (n = 11 observations). Hinds were maintained on a farm near Saskatoon, Saskatchewan (52°07′N, 106°38′W). The ovaries were examined daily during September through October by transrectral ultrasonography using a B-mode ultrasound machine and a 7.5 MHz linear array transducer for transition to estrus, and December through April for transition to anestrus. The first ovulation was recorded on September 15 and all hinds had ovulated for the first time by October 7. In 17 of 20 observations, the duration of the first interovulatory interval (IOI) was 9.3 ± 0.4 days (mean ± SEM). With one exception, these IOIs were characterized by one wave of follicular development. The remaining three IOIs ranged from 16 to 23 days and consisted of two or three waves of follicle development. The second ovulation occurred by October 15 in hinds with a short IOI and by October 17 in all remaining hinds. The mean dates of first and last ovulation were September 25 and February 7, respectively, an interval of 135 days. The median date of the last ovulation was February 15 and the range was from December 3 to March 22. Duration of the last IOI of the season (21.2 ± 0.6 days) was similar to the notional 21-day cycle for wapiti, but longer (P < 0.05) than the duration of the first IOI (10.9 ± 1.0 days). Maximum diameters of the first 2 ovulatory follicles were similar (11.3 ± 0.4 vs. 11.3 ± 0.2 mm), but were larger (P < 0.05) than the last 2 ovulatory follicles of the breeding season (10.3 ± 0.3 vs. 10.1 ± 0.4 mm). Maximum diameter of the corpus luteum (CL) tended (P = 0.06) to be smaller for the short IOI than for longer IOI of the first and last cycles. Diameter of the last CL of the season was not different from that of the previous CL (12.8 ± 0.6 vs. 12.5 ± 0.6 mm); however, it was detected for a longer period (22.3 ± 1.2 vs. 19.3 ± 0.7 days; P < 0.05). Estrous cycles during transition into the breeding season have been described as being irregular and those out of the breeding season as increasingly long. In the present study, the transition periods were characterized by regular events. Transition to regular estrous cycles was preceded by one short (9 days) IOI. The last IOI of the breeding season was the same as that reported during the rut. Transition to anestrus occurred most commonly in February and was marked by a failure of the dominant follicle to ovulate after luteal regression.

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