The Netherlands Pharmacovigilance Centre Lareb has received 12 reports of haematoma associated with the use of fluticaso
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esynchronization using a modified Ovsynch protocol or a single gonadotropin-releasing hormone injection 7 d before an Ovsynch-56 protocol for submission of lactating dairy cows to first timed artificial insemination P. D. Carvalho, J. N. Guenther, M. J. Fuenzalida, M. C. Amundson, M. C. Wiltbank, and P. M. Fricke1 Department of Dairy Science, University of Wisconsin, Madison 53706
ABSTRACT
Presynchronization strategies, such as PresynchOvsynch and Double-Ovsynch, increase fertility to timed artificial insemination (TAI) compared with Ovsynch alone; however, simpler presynchronization strategies could reduce costs and simplify reproductive management. Lactating Holstein cows (n = 601) were randomly assigned to 1 of 2 presynchronization treatments before beginning an Ovsynch-56 protocol (GnRH at 70 ± 3 DIM, PGF2α 7 d later, GnRH 56 h after PGF2α, and TAI 16 h later at 80 ± 3 DIM) for first TAI. Cows (n = 306) in the first treatment (Double-Ovsynch; DO) were presynchronized using a modified Ovsynch protocol (GnRH at 53 ± 3 DIM, 7 d later PGF2α, and GnRH 3 d later) ending 7 d before the first GnRH injection (G1) of an Ovsynch-56 protocol. Cows (n = 295) in the second treatment (GGPG) were presynchronized using a single injection of GnRH 7 d before G1 of an Ovsynch-56 protocol at 63 ± 3 DIM. Blood samples were collected at G1 and the PGF2α injections of the Ovsynch-56 protocol to determine progesterone (P4) concentrations. Pregnancy diagnosis was performed using ultrasonography 32 d after TAI, and pregnant cows were reexamined 46 and 70 d after TAI. Overall, DO cows had more pregnancies per artificial insemination (P/AI) compared with GGPG cows 32 d after TAI (53 vs. 43%). Overall, P/AI did not differ by parity (primiparous vs. multiparous), and pregnancy loss did not differ between treatments or parities. More DO cows had P4 in a medium range (>0.5 to 4 ng/mL) at the PGF2α injection of the Ovsynch-56 protocol compared with GGPG cows (67 vs. 36%). Thus, presynchronization with a modified Ovsynch protocol increased P/AI after TAI
Received April 10, 2014. Accepted June 23, 2014. 1 Corresponding author: [email protected]
at first AI by increasing synchrony to the Ovsynch-56 protocol compared with presynchronization using a single injection of GnRH. Key words: presynchronization, Ovsynch, DoubleOvsynch INTRODUCTION
Despite improvements in nutrition, cow comfort, and genetic selection for reproductive efficiency that have occurred over the past decade, pregnancies per artificial insemination (P/AI) continues to be low (~30%) in high-producing dairy cows inseminated after a detected estrus (Valenza et al., 2012; Fricke et al., 2014). Expression of behavioral estrus is poor in high-producing dairy cows (Lopez et al., 2004) and ranged from 50% after visual observation (Washburn et al., 2002) to 70% when insemination was based on an activity monitoring system for detection of estrus (Valenza et al., 2012), and inadequate and inaccurate detection of estrus continues to be a challenge on dairy farms (Palmer et al., 2010). Timed
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