Preovulatory Changes and Ovulation in Cattle Undergoing Spontaneous or Cloprostenol-Induced Luteolysis (original) (raw)
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Animal Reproduction Science, 1994
The aim of this study was to characterise the luteal and follicular response to artificially elevated concentrations of progesterone during the metoestrous phase of the oestrous cycle of heifers. An intravaginal controlled internal drug releasing (CIDR) device containing 1.9 g progesterone was inserted at either Day 1 of the cycle (oestrus designated Day 0) for 4 days (T 1; n = 12), or on Day 4 for 5 days (T4; n= 11). A third group of heifers (CTRL; n= 13) remained untreated. The diameters of the corpus luteum (CL) and all follicles of at least 5 mm were recorded daily in ovaries of eight heifers from each group by transrectal ultrasonography throughout the cycle. A blood sample was collected daily from every heifer to determine the concentrations of progesterone and iuteinising hormone (LH) in sera. Two of the heifers with elevated progesterone levels from Day l had 'short' cycles which were characterised by ovulation of the first dominant follicle following the premature demise of the CL. These data are considered separately from the general analysis. Progesterone concentrations of heifers in both treatment groups were elevated (P< 0.05) during the period of CIDR insertion, but were not different at the mid-cycle phase compared with untreated contemporaries. A sustained decline to basal concentrations of progesterone occurred earlier (P< 0.05) in heifers treated from Day 1. Elevated progesterone concentrations were associated with decreased (P< 0.05) mean concentrations of LH on Days 4 and 5 in heifers of the Tl group, but only on Day 5 in the T4 group. The average diameter of the corpus luteum (CL) of treated heifers from Days 8 to 18 was less than in untreated heifers (Days 11-13 and 16-18, P<0.05). Heifers in the T1 group had either one or two waves of follicle turnover, with a mean inter-oestrus interval of 8 days and 18 days, respectively. In contrast, heifers in other groups had some two-wave but mostly three-wave cycles and mean inter-oestrus intervals of about 21 days. Premature elevation of progesterone reduced (P < 0.05) the size of the first dominant follicle in both treated groups of heifers. Administration of progesterone during the early and late metoestrous phase of the oestrous cycle in heifers reduced the diameters of the CL and the first dominant follicle. Elevation of progesterone from Days 1 to 5, hut not from Days 4 to 9, reduced the lifespan of the CL to produce 'short' and 'shortened' cycles, with either one or two follicle waves, respectively.
Canadian journal of veterinary research = Revue canadienne de recherche veterinaire, 2004
The objective was to determine the effects of giving prostaglandin F2alpha (PGF) concurrent with, or 24 h before, removal of an intravaginal, progesterone-releasing (controlled internal drug release [CIDR]) device, on luteolysis, the synchrony of estrus and ovulation. Eighteen postpubertal Holstein heifers were given a CIDR and 100 microg gonadotropin releasing hormone (GnRH) and equally allocated to 3 groups. The PGF was given concurrently with CIDR removal after 7 or 8 d (groups D7/D7 and D8/D8, respectively) or given 1-d before removal of CIDR after 8 d (group D7/D8). There was no difference (P > 0.75) among groups in the intervals (h) from CIDR removal to onset of standing estrus and to ovulation (49.3 h+/-6.2 h and 77.5 h+/-9.0 h, respectively; least squares means+/-standard error of means). We also determined if stage of the estrus cycle influenced the synchrony of estrus or ovulation. In heifers in metestrus at CIDR insertion (versus those at estrus or diestrus), intervals...
Theriogenology, 2001
Predicting the functional activity of a dominant follicle (DF) and corpus luteum (CL) might be important before starting a superovulation regime or a synchronization program. The DF and CL were characterized morphologically by using ultrasonography and were characterized functionally by estimating the estradiol-17lYprogesterone (E,/P,) ratio. Their influence on ovarian function was estimated through their ability to ovulate at different stages of development in response to PGF,a-application. A total of 47 Holstein Friesian (35 cows and 12 heifers) were used in two experiments. In Experiment 1, 25 animals were examined by daily transrectal palpation and ultrasonography to follow the morphological development of the DF. The status of the DF was categorized into 3 groups (Al, Bl, Cl). The Al group (n=7) contained animals with DF in the growing phase or in early static growth phase for less than 3 days. Group Bl (n=13) included animals with DF in static growth phase for 3 to 4 days, while Group Cl (n=5) comprised animals with DF keeping a plateau for more than 4 days or animals with DF in the regression phase. The DF were aspirated transvaginally and the follicular fluid (FF) was analyzed for E, and P,. In Experiment 2, 22 animals were included. As in Experiment 1, the animals were classified into three groups (A2, n=lO; B2, n=5; C2, n=7). They were treated by a single dose of PGF,a (25 mg, im) between Days 8 and 12 of the cycle. Results showed that luteolyses occurred in all animals. The DF, which were in growing or in early static growth phase < 3 days were always E,-dominant (E, > PJ and ovulated after PGFp-application in 618 of cases and persisted in 2 (Group A2). The DF persisting > 4 days or that had been in regression were always P,dominant. This type of DF regressed after PGF,a-application (Group C2). The DF in early static growth phase for 3 to 4 days in 5113 cases were E,-dominant and in 8/l 3 cases were P,-dominant. This type of DF ovulated in 3/5 cases and regressed in 215 cases after PGF,a-application (Group B2). These results suggest that the DF is morphologically and functionally defined as long as the DF is in the growing or early static growth phase (A 1, A2) for at least 2 days or if the DF is in regression (C 1, C2). However, when the DF is in the static growth phase for 3 or 4 days (B 1, B2), their morphological and functional characteristics are different. The CL controlls ovulation in the A and C groups and plays an abettor's roll in the B-group.
Theriogenology, 2009
The objective of this study was to determine the effects of progesterone and cloprostenol (a PGF 2a analogue) on ovarian follicular development and ovulation in prepubertal heifers. In Experiment 1, crossbred Hereford heifers (Bos taurus; 10 to 12 mo old, 255 to 320 kg) were assigned randomly to three groups and given (1) an intravaginal progesterone-releasing insert (CIDR; P group, n = 13); (2) a CIDR plus 500 mg cloprostenol im (PGF 2a analogue) at CIDR removal (PPG group, n = 11); or (3) no treatment (control group, n = 14). The CIDR inserts were removed 5 d after follicular wave emergence. Progesterone-treated heifers (P and PPG groups) had a larger dominant follicle than that of the control group (P = 0.01). The percentage ovulating was highest in the PPG group (8 of 11, 73%), intermediate in the P group (4 of 13, 31%), and lowest in the control group (1 of 14, 7%; P < 0.02). In Experiment 2, 16 heifers (14 to 16 mo old, 300 to 330 kg) were designated to have follicular wave emergence synchronized with either a CIDR and 1 mg estradiol benzoate im (EP group, n = 8) on Day 0 (beginning of experiment) or by transvaginal ultrasoundguided ablation of all follicles !5 mm on Day 3 (FA group, n = 8). On Day 7, CIDRs were removed in the EP group, and all heifers received 500 mg cloprostenol im. Ovulation was detected in 6 of 8 heifers (75%) in both groups. In summary, the use of PGF 2a with or without exogenous progesterone treatment increased the percentage ovulating in heifers close to spontaneous puberty. #
Animal Reproduction Science, 2005
The effect of day of induced luteolysis on follicle dynamics, oestrus behaviour and ovulatory response in goats was studied by administering cloprostenol on Day 5 (n = 10), Day 11 (n = 10), or Day 16 (n = 10) after detection of oestrus. Stage of the luteal phase affected the interval from cloprostenol injection to onset of oestrus, with behavioural oestrus being observed earlier in goats treated early in the luteal phase (43.4 ± 3.2 h on Day 5 versus 57.0 ± 2.6 h on Day 11 and 56.7 ± 2.7 h on Day 16, P < 0.01). The group treated on Day 5 also tended to have a higher proportion of does which exhibited oestrus behaviour (P = 0.07) and ovulation (P = 0.06). In all the cycles, at least one of the ovulatory follicles arose from antral follicles present in the ovary at cloprostenol injection. In 66.7% of monovular cycles, the ovulatory follicle was the largest follicle on the day of luteolysis. In 33.3% of polyovulatory cycles, one of the ovulatory follicles was the largest one present when cloprostenol was administered. In 80% of polyovulatory cycles, the second ovulatory follicle was present on the day of luteolysis; but in the three remaining cycles, the second ovulatory follicle emerged later. This shows that the largest follicle may not exert dominance over other follicles in the goat. Evaluation of follicular dynamics in different phases of luteal activity in current experiment showed an attenuation of dominance in the mid-luteal period. In does treated early or late in the luteal * Corresponding author.
Animal Reproduction Science, 1990
In previous studies of heifers with two follicular waves during an estrous cycle, the dominant follicle of Wave 1 was first detected ultrasonically on approximately the day of ovulation (Day 0) when its diameter was 4-5 ram. On average, it grew linearly for 6 days (growing phase), remained the same size for 6 days (static phase), and then regressed (regressing phase). The dominant follicle of Wave 2 was first detected on approximately Day 9 and became the ovulatory follicle. In the present experiment, nonbred and bred heifers were treated with a luteolytic dose of prostaglandin F2,~ (25 mg) on Days 5, 8, or 12, when the dominant follicle of Wave 1 was expected to be in the growing, static, and regressing phase, respectively. There were no significant effects of breeding status on any end point. The hypothesis that growth of the dominant follicle during Wave 1 and response to prostaglandin F2,~ treatment is different between bred and nonbred heifers was not supported. Ovulation occurred from the dominant follicle of Wave 1 in 5 of 5, 6 of 6 and 0 of 4 heifers treated on Days 5, 8, and 12, respectively (P<0.005). Wave 2 was not detected in the Day-8 heifers, but was the origin of the ovulatory follicle in the Day-12 heifers. The results supported the hypothesis that the dominant follicle of Wave 1 is viable (capable of ovulation) before detection of Wave 2. For heifers treated on Days 5, 8, and 12, the ovulatory follicle had a mean diameter of 13.8, 17.3, and 11.8 mm, respectively, on the day of treatment and a mean diameter of 16.0, 19.5, and 16.4 ram, respectively, on the day prior to ovulation (significant increase between treatment and day prior to ovulation for each group). The results supported the hypothesis that the static-phase dominant follicle of Wave 1 is capable of further growth after luteolysis, even though it has apparently reached maximum diameter. The interval from treatment to ovulation was significantly shorter in Day-5 heifers (mean, 3.0 days) than in Day-12 heifers (mean, 4.5 days). In summary, the viable dominant follicle present at the time of luteolysis increased in diameter and became the ovulatory follicle.
Theriogenology, 1999
Ovarian changes determined by daily transrectal ultrasonic scanning, and its correlation with serum progesterone (P4) and estradiol (E2) concentrations were studied in seven cyclic Saanen goats, Estrous cycles were synchronized with 2 injections of a PGF2, analogue 9 d apart. All follicles 22 mm in diameter and CL were measured each day. One goat showed a longer interestrous interval, associated with development of a cystic-luteinized structure. The mean interovulatory interval for the other 6 goats was 20.8f0.4 d. The incidence of goats with 4, 3, and 2 follicular waves was 3, 1 and 2 respectively; follicular waves emerged on Days 0.5f0.6, 7.2fO 7, 10.7M.5 and 13.7fo.8 for Wave I, 2, 3 and the Ovulatory wave, respectively. The largest follicle of Wave 2 was smaller (4.9+0. I mm) than the largest follicles of Wave 3 (6.2rtO. I mm; P10.01) and of the Ovulatory wave (7.0+0.5 mm; P<O.Ol), and tended to be smaller than the largest follicle of Wave 1 (6.3ti.6 mm; P<O 09). Interval between emergence of Wave 1 and Wave 2 was longer than interval between emergence of Wave 2 and Wave 3 (7.3H.9 d vs 4.0fO 4 d; P<O.Ol), and between Wave 3 and the Ovulatory wave (3.8&l. 1 d; P50.05) Two days before ovulation, the diameter of the ovulatory follicle was larger (P<O.Ol) than the first subordinate follicle. Serum E2 concentrations increased from the day of ovulation (2.7kO.3 pg/mL) to Day 2 (7.6kO.9 pg/mL; P10.01) associated with the early-mid growing phase of the largest follicle of Wave 1, and then decreased to basal levels on Day 5 (P10.01) and peaked again (I 6.5k2.4 pg/mL) 2 d before ovulation. The CL were detected ultrasonically on Day 3 post ovulation and attained a mean maximum diameter of 33.5+0.8 mm between Days 8 and 14 The following characteristics were observed 1) ovarian follicular development in goats is wave-like; 2) increased P4 concentrations may be promoting follicular wave turnover; 3) it is suggested that the presence of follicular dominance and the production of E2 are different among waves. While in Wave 1 and in the Ovulatory wave, follicular dominance is present and production of E2 is consistent, no changes in serum E2 concentrations were found in other stages of the interovulatory interval. In the intervening waves, no indicators of follicular dominance could be firmly documented. 0 1999 by Elsevier Science lnc
Role of oestradiol in growth of follicles and follicle deviation in heifers
Reproduction, 2003
Follicle deviation is characterized by continued growth of the largest (developing dominant) follicle and reduced growth of the smaller (subordinate) follicles. The aim of the present study was to test the following hypotheses: (1) oestradiol contributes to the depression of circulating FSH encompassing follicle deviation and (2) oestradiol plays a role in the initiation of deviation. Heifers were treated with progesterone (n = 5) or antiserum against oestradiol (n = 7) or given no treatment (control; n = 6). On the basis of previous studies, progesterone treatment would decrease LH and thereby the circulatory and intrafollicular concentrations of oestradiol and the antiserum would reduce the availability of oestradiol. Progesterone was given in six 75 mg injections at 12 h intervals beginning when the largest follicle of wave 1 first reached 5.7 mm (t = 0 h). Oestradiol antiserum (100 ml) was given in a single injection at t = 12 h. Follicles of the wave were defined as F1 (largest) and F2, according to the diameter at each examination. Blood samples were collected at 12 h intervals during t = 0-72 h. Treatment with progesterone lowered the circulatory concentrations of LH by 12 h after the start of treatment (P < 0.05), and concentrations remained low compared with those of controls during the treatment period. Treatment with oestradiol antiserum had no effect on LH. Both progesterone and the antiserum treatments increased the FSH concentrations compared with controls (P < 0.05), which supports the first hypothesis. The interval from t = 0 h to the beginning of deviation was longer in the progesterone-(51.0 ± 7.6 h; P < 0.06) and antiserum (51.4 ± 6.3 h; P < 0.05)-treated groups than in the controls (38.0 ± 3.7 h), which supports the second hypothesis. There was no difference among groups in the diameters of F1 and F2 at deviation. Reduced diameter (P < 0.05 or P < 0.06) of both F1 and F2 occurred in both the progesterone-and antiserum-treated groups at t = 36 h and 48 h, compared with controls. Follicle retardation occurred in both the progesterone-and antiserum-treated groups despite the high FSH concentrations, whereas LH was altered only in the progesterone-treated group. Therefore, the follicle effect can be attributed to inadequate intrafollicular oestradiol. This interpretation implies a functional local role for oestradiol in the deviation process, independent of the systemic negative effect on FSH.