A Modified Presynchronization Protocol Improves Fertility to Timed Artificial Insemination in Lactating Dairy Cows

Abstract

To compare 2 hormonal protocols for submission of lactating dairy cows for timed artificial insemination (TAI), nonpregnant lactating Holstein cows (n = 269) >60 d in milk were randomly assigned to each of 2 treatments to receive TAI (TAI = d 0). Cows assigned to the first treatment (Ovsynch, n = 134) received 50 microg of GnRH (d -10), 25 mg of PGF2alpha (d -3), and 50 microg of GnRH (d -1) beginning at a random stage of the estrous cycle. Cows assigned to the second treatment (Presynch, n = 135) received Ovsynch but with the addition of 2 PGF2alpha (25 mg) injections administered 14 d apart beginning 28 d (d -38 and -24) before initiation of Ovsynch. All cows received TAI 16 to 18 h after the second GnRH injection. Ovulatory response after each GnRH injection for a subset of cows (n = 109) and pregnancy status 42 d after TAI for all cows were assessed using transrectal ultrasonography. Based on serum progesterone (P4) profiles determined for a subset of cows (n = 109), P4 concentrations decreased for Presynch cows after the first 2 PGF2alpha injections, and Presynch cows had greater P4 concentrations at the PGF2alpha injection on d -3 compared with Ovsynch cows. Although the proportion of cows ovulating after the first and second GnRH injections did not differ statistically between treatments (41.1 and 69.6% vs. 35.9 and 81.1% for Ovsynch vs. Presynch, respectively), pregnancy rate per artificial insemination (PR/AI) at 42 d post TAI was greater for Presynch than for Ovsynch cows (49.6 vs. 37.3%). Parity, DIM, and body condition score (BCS) at TAI did not affect PR/AI to TAI. These data support use of this presynchronization protocol to increase PR/ AI of lactating dairy cows receiving TAI compared with Ovsynch.

Expression and detection of estrus in dairy cows: the role of new technologies

“…Overall, cows in treatment 1 in which inseminations occurred as a combination between AI to activity and timed AI had fewer P/AI compared with cows in treatment two in which all cows received timed AI after completing the Presynch-Ovsynch protocol ( Table 2). The reduction in P/AI due to inseminating cows with increased activity after the second PGF 2α injection was expected because the increase in P/AI due to presynchronization with PGF 2α likely results from synchronizing estrus after the second PGF 2α injection (Navanukraw et al, 2004) so most cows initiate the Ovsynch protocol on days 5 to 9 of the ensuing estrus cycle, thereby improving P/AI to timed AI (Vasconcelos et al, 1999). Inseminating 70% of cows based on activity after the second PGF 2α injection removed the presynchronized cows from the protocol, thereby negating the increase in P/AI due to presynchronization.…”

“…A presynchronization strategy in which cows receive two injections of PGF 2α administered 14 days apart with the second PGF 2α injection 10 to 14 days before initiation of an Ovsynch protocol (i.e. Presynch-Ovsynch) increases fertility to timed AI in lactating dairy cows compared with Ovsynch alone (Moreira et al, 2001;Navanukraw et al, 2004). The Presynch-Ovsynch protocol has been widely adopted by dairies in the United States (Caraviello et al, 2006) and is a popular strategy for submitting cows for first AI because AI to detected estrus can be combined with timed AI for cows failing to be detected in estrus.…”

Efficacy of hCG and GnRH with Respect to Follicular Size and Presence of the Corpus Luteum in Cosynch Protocol Integrated with Norgestomet in Lactating Cows

“…Therefore, many veterinarians under field conditions prefer to perform TAI concurrently with the second GnRH injection. This strategy is known as Cosynch because it eliminates one handling of cows and facilitates once-daily restraint of cows for administration of hormone injections and TAI (12).…”

Reproductive Management of Lactating Dairy Cows for First Postpartum Insemination

“…Because of the convenience of giving injections on the same day of the week, many producers have opted for administering the PGF 2 α injections of the presynchronization protocol on the same day of the injections of the Ovsynch protocol, which results in an interval between presynchronization and initiation of Ovsynch of 14 days. Navanukraw et al (2004) clearly demonstrated that a 14 -day interval between presynchronization and initiation of the Ovsynch was benefi cial to P/ AI; however, in all these studies El -Zarkouny et al, 2004 ;Navanukraw et al, 2004 ), cows assigned to the control groups did not receive PGF 2 α during the postpartum period, which might improve uterine health and, then, fertility of dairy cows. Furthermore, although presynchronizing cows 14 days before initiating the Ovsynch improved P/AI compared with no presynchronization (Navanukraw et al, 2004 ), the interval is not optimal and results in poor ovulation rate to the initial GnRH of the Ovsynch (Chebel et al, 2006 ;Galv ã o et al, 2007 ).…”