Enhanced Precision of Estrus and Luteinizing Hormone After Progesterone and Prostaglandin in Heifers 1 (original) (raw)
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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...
Exogenous hormonal manipulation of ovarian activity in cattle
Domestic Animal Endocrinology, 2002
To achieve precise control of the oestrous cycle in cattle it is necessary to control both the life span of the corpus luteum and the follicle wave status at the end of the treatment. Antral follicle growth in cattle occurs in distinct wavelike patterns during the ovarian cycle and the postpartum anoestrous period. The emergence of each new wave is stimulated by a transient increase in FSH. Each follicle wave has an inherent life span of 7-10 days as it progresses through the different stages of development, viz., emergence, selection, dominance and atresia or ovulation. The dominant follicle (DF) is distinguishable from other subordinate follicles by its enhanced capacity to produce oestradiol, maintenance of low intrafollicular concentrations of insulin-like growth factor binding proteins-2,-4 and-5 and follistatin and an increase in free intrafollicular concentrations of IGF-I as well as an increase in size. Three approaches can be taken to control ovarian activity and regulate the oestrous cycle in cattle: (i) use of the luteolytic agent prostaglandin F2␣ (PGF2␣) alone or one of its potent analogues, (ii) administration of exogenous progesterone-progestagen treatments combined with the use of exogenous oestradiol or gonadotrophin releasing hormone (GnRH) to control new follicle wave emergence and shorten the life span of the corpus luteum, and (iii) prior follicle wave synchrony followed by induced luteolysis. A number of different oestrous synchronisation regimens, viz., PGF2␣-based only, short-term progesterone with prior follicle wave synchrony using oestradiol or GnRH have been developed but the problem of obtaining good follicle wave synchrony and CL regression limit their widespread application. GnRH-prostaglandin-GnRH regimens have recently been developed for beef and dairy cows. However, their success is variable. A better understanding of the hormonal control of follicle growth is a prerequisite in order to obtain more precise control the oestrous cycle allowing one AI at a predetermined time giving high pregnancy rates without recourse to detection of oestrus.
Theriogenology, 2019
An experiment was designed to evaluate the effect of extending duration of the presynchronization treatment in a long-term progestin-based estrus synchronization protocol. Heifers were assigned to either an 18 d (Day 0e18) or 14 d (Day 4 to Day 18) CIDR ® treatment (1.38 g progesterone controlled internal drug release insert; Zoetis, Madison, NJ), with prostaglandin F 2a (PG; 250 mg im cloprostenol sodium) administered 16 d after CIDR ® removal (Day 34). Heifers at two locations (location one, n ¼ 193; location two, n ¼ 649) were assigned to treatment based on reproductive tract score (RTS; Scale 1e5) and body weight. Heifers that were assigned RTS 1 were not retained for the trial (n ¼ 6). Estrus detection aids (Estrotect ®) were applied at PG. Split-time artificial insemination (STAI) was utilized and AI performed based on expression of estrus at 66 h. Expression of estrus was defined as removal of !50% of the grey coating from the Estrotect ® patch. Heifers that expressed estrus at 66 h were inseminated then and heifers that had not expressed estrus were inseminated at 90 h. Only heifers that failed to express estrus by 90 h received gonadotropin-releasing hormone (GnRH; 100 mg im gonadorelin acetate) at the time of AI. At location one, blood samples were collected at PG and AI (66 h or 90 h) from all heifers to determine E 2 concentration by radioimmunoassay, and transrectal ovarian ultrasound was performed to detail ovarian structures on a subset of heifers (n ¼ 73) at both time points. The proportion of heifers expressing estrus did not differ between treatments, either by 66 h (60%) or in total by 90 h (84%) after PG. Pregnancy rate to STAI did not differ between treatments (P ¼ 0.3; 52%, 14-d CIDR ®-PG; 50%, 18-d CIDR ®-PG), or at the end of the 60 d breeding season (P ¼ 0.2; 86%, 14-d CIDR ®-PG; 82%, 18-d CIDR ®-PG). No differences were detected in mean diameter of the dominant follicle at PG (P ¼ 0.6; 10.9 ± 0.4 mm, 14d CIDR ®-PG; 11.0 ± 0.4 mm, 18-d CIDR ®-PG) or at STAI (P ¼ 0.3; 12.6 ± 0.4 mm, 14-d CIDR ®-PG; 13.2 ± 0.4 mm, 18-d CIDR ®-PG), nor were any differences observed between treatments in concentrations of E 2 at PG (P ¼ 0.8; 1.1 ± 0.19 pg/ml, 14-d CIDR ®-PG; 1.1 ± 0.19 pg/ml, 18-d CIDR ®-PG) or STAI (P ¼ 0.6; 3.8 ± 0.19 pg/ml, 14-d CIDR ®-PG; 3.6 ± 0.19 pg/ml, 18-d CIDR ®-PG). These data indicate that duration of CIDR ® treatment can be extended from 14 to 18 d, thus providing flexibility in scheduling without compromising reproductive outcomes.
Enhanced precision of estrus and luteinizing hormone after progesterone and prostaglandin in heifers
Journal of dairy science, 1986
Objectives were to determine if low progesterone and increased basal luteinizing hormone for 3 d after injecting prostaglandin F2 alpha would affect precision of preovulatory surges of luteinizing hormone and onset of estrus in Holstein heifers. In experiments 1 and 2, heifers received progesterone devices for 10 d and prostaglandin F2 alpha on the 7th d after inserting progesterone device. For controls, progesterone devices were removed when prostaglandin F2 alpha was injected, and control devices were installed for 3 d. In experiment 1, jugular blood was sampled every 2 or 4 h from injection of prostaglandin F2 alpha until 108 h after removing progesterone to determine basal and peak secretion of luteinizing hormone. In treatment heifers, basal luteinizing hormone tended to increase, and intervals to peak secretion of luteinizing hormone were shorter and more precise than for controls. In experiment 2, heifers were observed for estrus for 30 min every 4 h for 96 h after removing p...
Reproduction, 1998
The aim of the present study was to develop a treatment protocol for the precise synchronization of oestrus that would avoid the development of persistent dominant ovarian follicles. Bos indicus heifers, in which oestrous cycles had been presynchronized, were allocated randomly, according to the day of their oestrous cycle, to one of five treatment groups. All heifers received a subcutaneous ear implant containing 3 mg of norgestomet for 17 days starting on day 0 and an injection of an analogue of prostaglandin F2\ g=a\ on days 0 and 4. Heifers in group 1 (control group; n = 7) received no other treatment, while heifers in groups 2 (n = 8), 3 (n = 7), 4(n = 7), and 5 (n= 7) received a single progesterone-releasing controlled internal drug release device (CIDR) for 24 h on days 10, 12, 14 and 16, respectively. Treatment with a single CIDR delayed the mean time of ovulation and the day of emergence of the ovulatory follicle in heifers treated on days 14 and 16 compared with control heifers (P<0.05). There was less variation in the interval to ovulation in heifers treated on day 10 compared with other treated heifers (P < 0.05). The variation among heifers in the day of emergence of the ovulatory follicle and the age of the ovulatory follicle at ovulation was less for all groups treated with a CIDR than for the control group (P<0.05). The duration of dominance and variation in the duration of dominance of the ovulatory follicle was less in heifers treated with a CIDR device on days 10 and 16 than for control heifers (P < 0.05). Mean age (days from emergence to ovulation) of the ovulatory follicle did not differ among treatment groups (P > 0.05). Concentrations of LH and oestradiol decreased coincident with increased concentrations of progesterone on the days of CIDR treatment in treated compared with control heifers (P < 0.02) but increased again after removal of the CIDR. A smaller proportion of follicles in the growing phase of follicular development at the time of CIDR treatment become atretic compared with follicles that had reached a plateau phase of follicular growth (14.3% (1/7) versus 90.5% (19/21), respectively; P < 0.001). It was concluded that acute treatment with progesterone can influence the growth pattern of ovarian follicular development. However, the effect varies with the stage of ovarian follicular development. Short term treatment with progesterone 7 days before the end of a 17 day period of norgestomet treatment resulted in precise synchrony of ovulation without the ovulation of a persistent dominant ovarian follicle.
Control of Oestrus and Ovulation in Cows
Although the methods and techniques that will be used to synchronize follicle growth and ovulation in the future may yet to be discovered, many tools that are needed may already exist. Once synchronous growth of a competent dominant follicle occurs, ovulation can be induced at a predictable time by applying drugs or hormones that induce LH release, or by administration of exogenous LH. Development of a practical method for fixed-time AI offers significant advantages to dairy producers if conception rates are close to those seen in breeding after detected estrus. Development of routine methods based on the use of GnRH and PGF for resynchronization should help dairy producers improve reproductive performance. The control of estrus and ovulation program can benefit dairy operation because it allows for timed AI of lactating dairy cows without detection of estrus. However, the cost hormone administration should be considered when selecting this form of reproductive technology for routin...
Journal of Dairy Science, 2008
The objective was to compare pregnancy rates in nulliparous Holstein heifers given PGF 2α 24 h before, or concurrent with, removal of an intravaginal progesterone-releasing (CIDR) insert in 3 timed artificial insemination (TAI) protocols. Heifers (from 2 herds) were assigned randomly, over 11 mo, to 1 of 3 modified Ovsynch protocols. On d 0 (without reference to the stage of the estrous cycle), all heifers were given 100 g of GnRH i.m. and a CIDR insert (containing 1.9 g of progesterone). In the PG-7/P4-8 protocol (n = 99), PGF 2α was given on d 7, and CIDR inserts were removed on d 8. In the PG-7/P4-7 (n = 98) and PG-8/P4-8 (n = 102) protocols, PGF 2α administration and CIDR removal occurred concurrently, on d 7 or 8, respectively. In all 3 protocols, a second GnRH treatment (100 g) was given 48 h after PGF 2α , with TAI 16 to 20 h later. Blood samples were collected (subset of 124 heifers) on d 0, 7, 10 or 11 (i.e., at TAI), and 17. Pregnancy rates (32 d after TAI) for protocols PG-7/P4-8, PG-7/P4-7, and PG-8/P4-8 were 61.8, 55.6, and 54.1%, respectively. Pregnancy rate was higher when synchronization was initiated during diestrus than when initiated at other stages (57.0 versus 34.8%). Although pregnancy rates were not affected by season, there was an interaction between protocol and season; pregnancy rates were significantly lower in summer in heifers subjected to PG-7/P4-7 and PG-8/P4-8, but season did not affect pregnancy rates in heifers subjected to PG-7/P4-8. In summary, giving PGF 2α 24 h before CIDR removal, followed by TAI (PG-7/P4-8 protocol), resulted in consistent pregnancy rates, regardless of season, relative to protocols involving PGF 2α treatment concurrent with CIDR removal.