Article

Pregnancy per artificial insemination after presynchronizing estrous cycles with the Presynch-10 protocol or prostaglandin F2α injection followed by gonadotropin-releasing hormone before Ovsynch-56 in 4 dairy herds of lactating dairy cows1

Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201. Electronic address: .
Journal of Dairy Science (Impact Factor: 2.57). 08/2012; 95(11):6513-22. DOI: 10.3168/jds.2012-5707
Source: PubMed

ABSTRACT

The objective was to determine the effect of 2 presynchronization treatments on first-service pregnancy per artificial insemination (P/AI) in 4 dairy herds during warm and cool seasons of the year. Cows with ear tags ending with even digits at calving were enrolled in Presynch-10 (Presynch-10): two 25-mg injections of PGF(2α) (i.e., PG-1 and PG-2) 14 d apart. Cows with ear tags ending with odd digits were enrolled in PG-3-G: one 25-mg injection of PG (Pre-PG) 3 d before injection of 100μg of GnRH (Pre-GnRH), with the Pre-PG injection administered at the same time as PG-2 in the Presynch-10 treatment. Ten days after PG-2 or Pre-PG, all cows were enrolled in a timed AI protocol (Ovsynch-56; injection of GnRH 7 d before GnRH-1 and 56 h after GnRH-2 PG with AI 16 to 18 h after GnRH-2). Median days in milk (DIM) at scheduled timed AI were 75 d, which did not differ among herds. Cows detected in estrus before the scheduled timed AI were inseminated early (early bred, EB). Pregnancy was diagnosed at d 32 to 38 and at d 60 to 66 after timed AI by transrectal ultrasonography or transrectal palpation. Data were analyzed with herd as a random effect and with fixed effects of treatment (EB, Presynch-10, or PG-3-G), parity (primiparous vs. multiparous), season [hot (June through September) vs. cool-cold (October through May)], DIM, estrus at timed AI (0 vs. 1), and all 2-way interactions with treatment. The P/AI at d 32 to 38 for EB (n=472), Presynch-10 (n=1,247), and PG-3-G (n=1,286) were 31.4, 35.0, and 41.2%, respectively; P/AI at d 60 to 66 was 29.8, 32.2, and 37.3%, respectively. Season significantly influenced P/AI at d 32 to 38 and d 60 to 66, but a treatment by season interaction was not detected. The P/AI for PG-3-G and Presynch-10 treatments did not differ during cool-cold weather (d 32 to 38: 46.8 vs. 44.3%; d 60 to 66: 41.6 vs. 41.1%, respectively), but PG-3-G and Presynch-10 produced more P/AI than EB at d 32 to 38. During the summer, P/AI in PG-3-G was greater than in Presynch-10 (d 32 to 38: 35.9 vs. 26.7% and d 60 to 66: 33.2 vs. 24.4%, respectively), and P/AI in EB cows did not differ from that of Presynch-10 cows. Although pregnancy loss did not differ for EB, Presynch-10, and PG-3-G treatments (4.0, 6.7, and 9.3%, respectively), pregnancy loss from d 32 to 38 and d 60 to 66 was 2-fold greater in thinner cows (<2.5 vs. ≥2.5; 9.0 vs. 4.4%). We concluded that presynchronizing estrous cycles with PG-3-G produced more P/AI than inseminating cows at estrus during cooler weather and was superior to Presynch-10 during the summer.

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    • "Overall, lactating dairy cows exposed to PG-presynch programs have 42% greater odds of pregnancy compared with cows receiving only the timed AI program [8]. Presynchronization programs before first postpartum AI that include combinations of GnRH and PG (i.e., GnRH-PG presynch options): PG-3-G [9] [10]; G-6-G [11]; or Double Ovsynch [12] [13] before a timed AI program have become alternatives to standard PG-presynch programs because they often further improved P/AI. The mechanism of advantage of these programs includes inducing ovulation in anovulatory cows [9], decreasing the percentage of cows with low circulating progesterone concentrations (<0.50 ng/mL) at GnRH-1, increasing the percentage of cows with medium progesterone concentrations (0.50 < progesterone 3.0 ng/mL) at GnRH-1, and increasing the proportion of cows with a CL at GnRH-1 [9] [14]. "
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    ABSTRACT: The objective was to determine the benefit of including GnRH and PGF2α (PG) as a part of a presynchronization option before enrolling cows in a timed artificial insemination (AI) program. Holstein cows in one herd were assigned weekly at calving from January 2012 to August 2014 to a completely randomized design consisting of two presynchronization treatments. Cows in the Presynch-11 (n = 290) control were administered two PGF2α injections (Presynch PG-1 and Presynch PG-2) 14 days apart starting at 39 ± 4 days postpartum (study Days 0 and 14). Cows receiving the experimental presynchronization treatment (Gsynch-11, n = 287) were treated with GnRH (pre-GnRH) on study Day 7 and PG (pre-PG) on study Day 14. On study Day 25, all cows were enrolled in the Ovsynch-56 timed AI program: GnRH-1 on study Day 25, PG on study Day 32, GnRH-2 on study Day 34, 56 hours after PG, and timed AI on study Day 35, 16 hours after GnRH-2. In a subsample of 255 cows, ovarian structures were monitored for size and ovulation, and blood samples were collected on study Days 7, 14, 25, 32, 34, and 41 to measure progesterone. Concentrations of progesterone were greater (P < 0.05) in Gsynch-11 than Presynch-11 cows before pre-GnRH was administered (3.3 ± 0.3 vs. 2.1 ± 0.3 ng/mL), respectively, and ovulatory response to the pre-GnRH treatment also was greater (P = 0.008) in Gsynch-11 than Presynch-11 cows (53.2 vs. 35.0%), respectively. One week later, the dominant follicle was larger (P = 0.045) in Presynch-11 than Gsynch-11 cows. Eleven days after completing the presynchronization treatments, ovulatory response to the Ovsynch GnRH-1 treatment was greater (P = 0.016) in Presynch-11 than Gsynch-11 cows (62.2% vs. 45.6%), respectively. At the time of the Ovsynch-PG treatment, more (P = 0.019) Presynch-11 than Gsynch-11 cows had at least one CL. Subsequent luteal regression (>96%), ovulation to GnRH-2 (>90%), and synchronization risk (>88%) did not differ between treatments, but incidence of multiple ovulation after GnRH-2 was larger (P = 0.036) in Presynch-11 than Gsynch-11 cows (28.4% vs. 15.9%), respectively. Pregnancy per AI at 32 days (36.4% vs. 35.1%) and 60 days (30.0% vs. 29.0%) after AI did not differ between Gsynch-11 and Presynch-11 cows, respectively, but was suppressed during summer months in both treatments to less than 70% of the pregnancy per AI of nonsummer months. Because more than 90% of the cows were ovular as treatments were applied, the GnRH treatment of Gsynch-11 could not be assessed for its benefit in anovular cows. The Gsynch-11 presynchronization treatment performed comparably with the standard Presynch-11 program and provides a viable presynchronization option for use before first AI in dairy herds.
    No preview · Article · Dec 2015 · Theriogenology
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    • "Likewise, a larger proportion of heifers exhibited a new follicular wave at the start of a TAI protocol when they were injected with PG 3 days before the initiation of the protocol [12]. Lactating dairy cows had better pregnancy outcomes during the summer when they were treated with PG and GnRH (3 days after PG and 7 days before the start of the Ovsynch protocol) than cows whose estrous cycles were presynchronized with two PG injections 14 days apart, with the second PG injection administered 10 days before Ovsynch [13]. We hypothesized that treatment with PG or PG followed by GnRH before the start of the 7-day CO-Synch þ CIDR protocol would improve pregnancy outcomes by altering concentrations of progesterone at the onset of the TAI protocol. "
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    ABSTRACT: We hypothesized that pregnancy outcomes may be improved by inducing luteal regression, ovulation, or both (i.e., altering progesterone status) before initiating a timed AI program in suckled beef cows. This hypothesis was tested in two experiments in which cows were treated with either PGF2α (PG) or PG + GnRH before initiating a timed AI program to increase the proportion of cows starting the program in a theoretical marginal (< 1 ng/mL; Experiment 1) or elevated (≥ 1 ng/mL; Experiment 2) progesterone environment, respectively. The control was a standard CO-Synch + CIDR program employed in suckled beef cows (100 μg GnRH im [GnRH-1] and insertion of a progesterone-impregnated intravaginal controlled internal drug release [CIDR] insert on study Day -10, 25 mg PG im and CIDR insert removal on study Day -3, and 100 μg GnRH im [GnRH-2] and timed AI [TAI] on study Day 0). In both experiments, blood was collected before each injection for later progesterone analyses. In Experiment 1, cows at 9 locations (n = 1,537) were assigned to either: (1) control or (2) PrePG (same as control with a PG injection on study Day −13). The PrePG cows had larger (P < 0.05) follicles on study Day −10 and more (P < 0.05) ovulated after GnRH-1 compared with control cows (60.6 vs. 36.5%), but pregnancy per TAI was not altered (55.5 vs. 52.2%, respectively). In Experiment 2, cows (n = 803) at 4 locations were assigned to: (1) control or (2) PrePGG (same as control with PG injection on study Day −20 and GnRH injection on study Day −17). Although pregnancy per TAI did not differ between control and PrePGG cows (44.0 vs. 44.4%, respectively), cows with BCS > 5.0 or ≥ 77 d postpartum at TAI were more (P < 0.05) likely to become pregnant than thinner cows or those with fewer days postpartum. Presynchronized cows in both experiments were more (P < 0.05) likely than controls to have luteolysis after initial PG injections and reduced (P < 0.05) serum progesterone; moreover, treatments altered the proportion of cows and pregnancy per TAI of cows in various progesterone categories before the onset of the TAI protocol. In combined data from both experiments, cows classified as anestrous before the study but with elevated progesterone on D −10 had increased (P < 0.05) pregnancy outcomes compared with anestrous cows with low progesterone concentrations. Progesterone concentration had no effect on pregnancy outcome of cycling cows. In summary, luteal regression and ovulation were enhanced and progesterone concentrations were altered by presynchronization treatments before the 7-d CO-Synch + CIDR program, but pregnancy per TAI was not improved.
    Full-text · Article · Jul 2014 · Theriogenology
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    • "Ovulation incidence in response to Pre-GnRH was increased in cows receiving d-31 PG-3-G-RES compared with d-41 RES treatment. Similar presynchronization treatments before first AI including PG and GnRH have reported ovulation incidence of 80 to 90% (Bello et al., 2006; Stevenson et al., 2012; Pulley et al., 2015). "

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