Effect of extending the interval from Presynch to initiation of Ovsynch in a Presynch-Ovsynch protocol on fertility of timed artificial insemination services in lactating dairy cows

Abstract

The specific objective of this study was to determine if increasing the interval between the Presynch and Ovsynch portion of the Presynch-Ovsynch protocol (Presynch: PGF2α-14 d-PGF2α and Ovsynch: GnRH-7 d-PGF2α-56 h-GnRH-16-20 h-timed artificial insemination) from 12 to 14 d would reduce the fertility of lactating dairy cows not detected in estrus after Presynch that receive timed artificial insemination (TAI). Cows from 4 commercial dairy farms (n=3,165) were blocked by parity (primiparous vs. multiparous) and randomly assigned to a 12 (PSOv14-12; n=1,566) or 14 d (PSOv14-14; n=1,599) interval between the second PGF2α (PGF) injection of Presynch (P2) and the beginning of Ovsynch. Cows detected in estrus any time between P2 and the day of the TAI were inseminated (AIED group). From a subgroup of cows (177 and 150 in PSOv14-12 and PSOv14-14, respectively), ovarian parameters and ovulation were evaluated through determination of concentrations of progesterone (P4) in blood and transrectal ultrasonography at the time of the first GnRH (GnRH1) and the PGF injection of Ovsynch. Overall, 52.8% (n=1,671) of the cows were AIED, whereas 47.2% (n=1,494) received TAI. For cows that received TAI, pregnancies per artificial insemination 39 d after artificial insemination were similar for PSOv14-12 (36.3%) and PSOv14-14 (36.0%) but were greater for primiparous (41.5%) than multiparous cows (33.6%). Pregnancy loss from 39 to 105 d after artificial insemination was similar for PSOv14-12 (4.8%) and PSOv14-14 (8.6%), for primiparous (6.4%) and multiparous cows (7.0%), but a tendency for a treatment by parity interaction was observed. Both treatments had a similar proportion of cows with a follicle ≥ 10 mm and similar follicle size at GnRH1; however, the ovulatory response to GnRH was greater for PSOv14-12 (62.2%) than PSOv14-14 (46.4%). A greater proportion of cows with a functional corpus luteum (75.3 vs. 65.6%) and greater concentrations of P4 (3.9 vs. 3.3 ng/mL) at GnRH1 in PSOv14-14 than PSOv14-12 may have compensated for the reduction in fertility expected due to reduced ovulatory response to GnRH1. We concluded that extending the interval from Presynch to Ovsynch from 12 to 14 reduced ovulatory response to GnRH1 but did not reduce the fertility of cows that received TAI when cows were inseminated in estrus after presynchronization. Thus, farms that combine AIED and TAI during the Presynch-Ovsynch protocol may use a 14-d interval between Presynch and Ovsynch to simplify their management without reducing fertility of cows receiving TAI.

Reproductive performance of replacement dairy heifers submitted to first service with programs that favor insemination at detected estrus, timed artificial insemination, or a combination of both

“…These programs can help reduce time to pregnancy after the end of the voluntary waiting period through rapid insemination of most cows after Presynch and immediate submission to TAI of those cows not detected in estrus. Programs such as Presynch-Ovsynch (Chebel et al, 2006;Fricke et al, 2014;Giordano et al, 2016) and Presynch-Cosynch (Stevenson, 2011;Ribeiro et al, 2012) have been extensively evaluated and are widely used for first service management of lactating dairy cows (Caraviello et al, 2006;Ferguson and Skidmore, 2013). In spite of the fact that these programs may effectively improve reproductive performance of dairy heifers, they have not been evaluated extensively in research and are rarely used for heifers in commercial farms (NAHMS, 2018).…”

Strategies for induction of ovulation for fixed-time AI in lactating dairy cows submitted to a novel presynchronization protocol

“…Since a presynchronization strategy was used in the study, the ovulation in response to GnRH of the Ovsynch protocol could be higher, as reported by other authors that obtained over 80% of ovulation rate to the first GnRH of the FTAI protocol in Presynch-Ovsynch or Double-Ovsynch-synchronized cows (Gumen et al, 2012;Ayres et al, 2013). However, the ovulation rate of the present study was similar to other studies that reported rates around 60-70% (Souza et al, 2008;Giordano et al, 2013;Giordano et al, 2016). It should be mentioned that the 16.8 µg dose of buserelin acetate used on D0 of our study represents 68% more in relation to the recommended dose of 10.0 µg (Monteiro et al, 2015).…”

“…The proportion of cows with CL on D6, which was the moment of first PGF of the FTAI protocols, was high (~90%) and did not differ (P = 0.34) between experimental groups (Table 3). Studies using Presynch-Ovsynch or Double-Ovsynch also reported high (87 to 100%) proportion of cows with CL on that day (Ayres et al, 2013;Carvalho et al, 2015;Dirandeh et al, 2015;Giordano et al, 2016). Therefore, in our study, more than 90% of the cows had at least one CL during development of the preovulatory follicle, providing an adequate circulating P4 milieu for optimized fertility.…”

“…Although studies reported no effect of ovulation in response to first GnRH of the Ovsynch protocol on fertility, especially in cows with high P4 at the beginning of the protocol (Giordano et al, 2016), generally, cows that ovulated at the onset of the protocol had higher P/AI 30 d (Giordano et al, 2013;Bisinotto et al, 2015b;Carvalho et al, 2015) and 60 d (Chebel et al, 2006;Bisinotto et al, 2015b) after FTAI. In our study, there were no interactions between ovulation on D0 and presence of CL (P = 0.40) or treatment (P = 0.44) on fertility responses.…”

“…The P/AI 31 days after FTAI was higher (P = 0.002) for farm 6 compared to the other herds ( There was no interaction (P = 0.46) between parity and treatment on P/AI 31 d after FTAI, however primiparous had higher (P < 0.001) P/AI than multiparous cows in the 3 experimental treatments (Figure 9). In several studies that used primiparous and multiparous cows, the fertility was higher for primiparous (Pereira et al, 2016), even more in first postpartum FTAI (Carvalho et al, 2014;Giordano et al, 2016), since primiparous are producing less milk because they are in first lactation and may have fewer health problems postpartum such as subclinical hypocalcemia (Reinhardt et al, 2011) and metabolic or clinical disorders (Cheong et al, 2011;Pascottini et al, 2017). Another aspect that was recently discussed in the literature about fertility in primiparous and multiparous cows is uterine size.…”