Luteal function, largest follicle, and fertility in postpartum dairy cows treated with 14dCIDR-PGF2α versus 2xPGF2α-Ovsynch for timed AIby Rebecca C. Escalante, Scott E. Poock, Matthew C. Lucy

Theriogenology

About

Year
2013
DOI
10.1016/j.theriogenology.2013.07.017
Subject
Equine / Food Animals / Small Animals / Animal Science and Zoology

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Luteal function, largest f treated with 14dCIDR-PG

Rebecca C. Escalante a, Scott E. aDivision of Animal Sciences, University of Missouri, C bCollege of Veterinary Medicine, University of Missou a r t i c l e i n f o

Article history:

Received 1 April 2013

Received in revised form 18 July 2013

Accepted 20 July 2013

Keywords:

Timed artificial insemination

Presynchronization

Progesterone * Corresponding author. Tel.: þ1 573 882 9897; fax: þ1 573 882 6827

E-mail address: lucym@missouri.edu (M.C. Lucy).

Contents lists available at ScienceDirect

Theriogenology

Theriogenology 80 (2013) 903–913PGF2a treatment) had greater P/AI than those not observed in estrus (55/103; 53.4% vs. 60/ 160; 37.5%; observed vs. not observed; P < 0.01; d 32 pregnancy diagnosis). When progesterone data were examined in a subset of cows (n ¼ 208), 55.3% of cows had a “prototypical” response to treatment (i.e., the cow had an estrous cycle that was synchronized by the presynchronization treatment and then the cow responded appropriately to the subsequent PGF2a and GnRH treatments before timed AI). Collectively, cows with a prototypical response to either treatment had 52.2% P/AI that was greater (P < 0.001) than the

P/AI for cows that had a nonprototypical response (19%) (P/AI determined at 60–90 days of pregnancy). In conclusion, we did not detect a difference in P/AI when postpartum dairy cows were treated with 14dCIDR-PGF2a or 2xPGF2a-Ovsynch before timed AI. The primary limitation to the success of either program was the failure of the cow to respond appropriately to the sequence of treatments.  2013 Elsevier Inc. All rights reserved.Dairy cow0093-691X/$ – see front matter  2013 Elsevier Inc http://dx.doi.org/10.1016/j.theriogenology.2013.07.01ollicle, and fertility in postpartum dairy cows

F2a versus 2xPGF2a-Ovsynch for timed AI

Poock b, Matthew C. Lucy a,* olumbia, USA ri, Columbia, USA a b s t r a c t

A method for timed artificial insemination (AI) that is used for beef cows, beef heifers, and dairy heifers employs progesterone-releasing inserts, such as the controlled internal drug release (CIDR; Zoetis, New York, NY, USA) that are left in place for 14 days. The 14-day CIDR treatment is a method of presynchronization that ensures that cattle are in the late luteal phase of the estrous cycle when PGF2a is administered before timed AI. The objective of this study was to test the effectiveness of the 14dCIDR-PGF2a program in postpartum dairy cows by comparing it with the traditional “Presynch-Ovsynch” (2xPGF2a-Ovsynch) program. The 14dCIDR-PGF2a cows (n ¼ 132) were treated with a CIDR insert on Day 0 for 14 days. At 19 days after CIDR removal (Day 33), the cows were treated with a luteolytic dose of PGF2a, 56 hours later were treated with an ovulatory dose of GnRH (Day 35), and 16 hours later were inseminated. The 2xPGF2a-Ovsynch cows were treated with a luteolytic dose of PGF2a on Day 0 and again on Day 14. At 12 days after the second PGF2a treatment (Day 26), the cows were treated with GnRH. At 7 days after GnRH, the cows were treated with PGF2a (Day 33), then 56 hours later treated with GnRH (Day 35), and then 16 hours later were inseminated. There was no effect of treatment or treatment by parity interaction on pregnancies per AI (P/AI) when pregnancy diagnosis was performed on Day 32 (115/ 263; 43.7%) or Days 60 to 90 (99/263; 37.6%) after insemination. There was an effect of parity (P < 0.05) on P/AI because primiparous cows had lesser P/AI (35/98; 35.7%) than multiparous cows (80/165; 48.5%) on Day 32. Cows observed in estrus after the presynchronization step (within 5 days after CIDR removal or within 5 days after the secondjournal homepage: www.ther io journal .com. All rights reserved. 7

R.C. Escalante et al. / Theriogenology 80 (2013) 903–9139041. Introduction

Timed artificial insemination (AI) programs are used in the dairy industry to ensure that every eligible cow is inseminated within the desired postpartum interval [1].

The first widely used timed AI program for lactating dairy cows was Ovsynch [2]. The Ovsynch program incorporates a series of hormonal treatments (GnRH, 7 days, PGF2a, 2–3 days, GnRH, 0–24 hours, AI) to synchronize a follicular wave, regress the CL, and synchronize an ovulation. Pregnancies per AI (P/AI) for the Ovsynch programwere greater if the program was started between Day 5 and 10 of the estrous cycle [3]. To achieve this desired improvement in P/AI, a presynchronization step (two treatments of PGF2a, 14 days apart) was devised to bring cows into a synchronized estrus before Ovsynch ([3]; “Presynch-Ovsynch” or 2xPGF2a-Ovsynch program). For this program, Ovsynch is started 10 to 14 days after the second PGF2a treatment, which is an optimal timing if a 3- to 5-day interval to estrus after PGF2a is assumed [4]. Later, it was found that giving the GnRH treatment 56 hours after the final PGF2a treatment and insemination 16 hours later yielded an additional improvement [5]. The final program called “PresynchOvsynch56” (further referred to as “2xPGF2a-Ovsynch in this article) is now a common option for timed AI in the dairy industry [6].

A method for timed AI that is used for beef cows, beef heifers, and dairy heifers employs progesterone-releasing inserts, such as the controlled internal drug release (CIDR, insert; Zoetis, New York, NY, USA) that are left in place for 14 days [7–11]. Treating cattle with the CIDR will suppress estrus, inhibit ovulation, and cause the development of a persistent dominant follicle [12]. The persistent dominant follicle can ovulate after CIDR removal [13]. The 14-day

CIDR treatment is a method of presynchronization. Ovulation of the dominant follicle creates a synchronized estrous cycle that can be used to optimize a timed AI program [14].

In the original programs, GnRH was administered 9 days after CIDR withdrawal (approximately Day 7 of the estrous cycle if it is assumed that cattle are in estrus 2 days after

CIDR removal [7]). In this original program, cattle were treated with PGF2a 16 days after CIDR removal (i.e., 1 week after GnRH), and the PGF2a treatment was followed by a timed AI [7] or insemination after estrus [9]. Later work indicated that the GnRH 9 days after CIDR removal did not improve synchrony of estrus, so this treatment was eliminated from the program [15]. The subsequent timed AI program (CIDR in, 14 days, CIDR out, 16 days, PGF2a, 48–72 hours, GnRH and timed AI) was named “Show-Me-Synch” or 14dCIDR-PGF2a and its efficacy was revealed in beef heifers [10] and dairy heifers [11].