Effect of progesterone supplementation on fertility responses of lactating dairy cows with corpus luteum at the initiation of the Ovsynch protocol

Certain hormonal profiles of postpartum anestrus jersey crossbred cows treated with controlled internal drug release and ovsynch protocol

“…The circulating progesterone value in Group 1 increased significantly (p<0.05) to 3.57±0.39 on day of removal than the pre-treatment value of 1.74±0.34 and it was significantly higher (p<0.05) from the Group 2. This finding corroborates the observation made by earlier workers [4,8-11]. However, Mishra et al .…”

Randomised controlled trial of the effect of concentration of progesterone before artificial insemination on fertility in ovulatory and anovulatory Bos indicus cattle

“…7 Significant increases in pregnancy rates were, however, confined to cows that did not have a CL at the start of the synchronisation treatment or that underwent timed insemination without the detection of oestrus. One study found that P4 supplementation as part of an Ovsynch protocol reduced pregnancy rates to AI in cows that were inseminated at a set time and which maintained their CL until administration of prostaglandin F2α (40.3% vs 46.7%), 30 but reported increased pregnancy rates to AI in those that did not have a CL at that time (38.1% vs 27.7%). Other studies have failed to detect differences in pregnancy rates when cattle with synchronised oestrous cycles have been exposed to higher P4 concentrations before ovulation.…”

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

“…In relation to EC/G group, several studies reported higher estrus expression in cows that had their ovulation induced by GnRH but also received E2 supplementation (Souza et al, 2007;Brusveen et al, 2009). Lastly, the estrus expression in cows from the G group was higher compared to other studies that used GnRH to induce ovulation and reported 24 to 35% of estrus (Ribeiro et al, 2012;Bisinotto et al, 2013Bisinotto et al, , 2015aBisinotto et al, , 2015b, but was similar to the 44% obtained by Souza et al (2007). The possible increased estrus expression in group G could be due to the fact that in our study we used two treatments with PGF, and the first one was administered on D6 of the protocol and not on D7 as in the traditional Ovsynch protocols.…”

“…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.…”

“…We confirmed our hypothesis that cows expressing estrus would achieve higher fertility, because expression of estrus increased P/AI on d31 in 69% and on d60 in 57% (Table 2). It is well-known that estrus expression at the end of FTAI protocols increases fertility parameters as shown by Bisinotto et al (2015b), who reported that expression of estrus increased ~10 percentage points P/AI on d32 (50.2 vs. 40.4%) and on d60 (46.0 vs. 35.8) in cows submitted to the Ovsynch protocol. Likewise, in a retrospective study with more the 5,430 FTAIs analyzed, Pereira et al (2016) reported that in protocols using EC as ovulation inducer, estrus expression increased P/AI on d30 and d60 in 13 percentage points.…”