Effects of progestagen exposure duration on estrus synchronization and conception rates of crossbreed ewes undergoing fixed time artificial insemination

Abstract

Synchronization of estrus and ovulation are of paramount importance in modern livestock improvement programs. These methods are critical for assisted reproduction technologies, including artificial insemination and embryo transfer, that can increase productivity. In the current study, subcutaneous implants containing norgestomet were placed for long (14 days), medium (9 days), and short (5 days) periods of time in 70 crossbred ewes undergoing fixed-time artificial insemination. The resulting effects on estrus synchronization and conception rates were subsequently evaluated. Among the synchronized ewes, 85.7% (60/70) underwent estrus over a period of 72 h after progestagen treatment ceased. The shortest mean interval between withdrawal of the device and onset of estrus (34.2 ± 8.9 h) was observed in the G14 days of P4 group (p < 0.05). The conception rate of the G14 days of P4 group was statistically higher than that of the other groups (83.3% vs. 60.9% vs. 47.8%; p < 0.05). In conclusion, 14 days of norgestomet treatment produced higher conception rates and a greater number of pregnancies at the beginning of the breeding season.

Different estrus induction protocols and fixed time artificial insemination during the anoestrous period in non-lactating Kivircik ewes

“…Similarly, Ataman et al (2009) reported earlier estrous detection rate in Akkaraman cross bred ewes treated with ear implant containing 3 mg norgestomet, compared to ewes treated with intravaginal sponge containing 30 or 40 mg FGA at the transition from non-breeding to breeding period. Considering our overall estrous detection rate for the first 12.0 ± 6.0 h period (46.8%), our result was higher than that reported by Ungerfeld and Rubianes (1999), Das et al (2000), Simonetti et al (2000), Dogan and Nur (2006), Hashemi et al (2006), Ustuner et al (2007) and Blaschi et al (2014). There were no significant differences among the 3 groups in terms of estrous detection rate within 72 h after progesterone removal.…”

“…It has been reported that the onset of estrous occured within 18-144 h following withdrawal of progesterone impregnated sponges (Das et al, 2000), MAP or FGA impregnated sponges (Ungerfeld and Rubianes, 1999;Simonetti et al, 2000;Gokcen et al, 2000;Dogan and Nur, 2006;Hashemi et al, 2006;Ustuner et al, 2007) or norgestomet ear implants (Cardwell et al, 1998;Ataman et al, 2009;Blaschi et al, 2014). In the present study, ewes detected in estrous between 12 and 72 h after sponge and implant removal; the highest incidence of estrous onset occured between 30 and 42 hours (Fig.…”

“…There were no significant differences among the 3 groups in terms of estrous detection rate within 72 h after progesterone removal. The estrous detection rate recorded during the 72 h observation period following the cessation of treatment (overall mean rate 86.1%) is within the range of 42.0-100% quoted in treatment with progesterone (Das et al, 2000) or FGA or MAP intravaginal sponges alone (Ungerfeld and Rubianes, 1999;Simonetti et al, 2000;Ataman et al, 2009) or in combination with eCG (Zarkawi et al, 1999;Gokcen et al, 2000;Ungerfeld and Rubianes, 2002;Zeleke et al, 2005;Hashemi et al, 2006;Ustuner et al, 2007) and PGF2α (Dogan and Nur, 2006) or norgestomet ear implants alone (Ataman et al, 2009) or in combination with eCG (Cardwell et al, 1998;Awel et al, 2009;Garoussi et al, 2012;Uslu et al, 2012 ) and PGF2α (Blaschi et al, 2014), in different breeds of ewes under different environmental conditions.…”

“…Sometimes prostaglandin F2α injected at sponge removal or 48 h prior to sponge removal (Gordon, 1999;Wildeus, 2000;Ungerfeld and Rubianes, 2002;Dogan and Nur, 2006;Ustuner et al, 2007). Moreover, norgestomet ear implants can easily be used in sheep for estrous synchronization (Cardwell et al, 1998;Awel et al, 2009;Ataman et al, 2009;Garoussi et al, 2012;Uslu et al, 2012;Blaschi et al, 2014). Gonadotrophins, such as equine chorionic gonadotrophin (eCG), have been shown to stimulate follicular growth, increase ovulation rate and fertility and induce a tighter synchrony of ovulation in both anestrous (Maurel et al, 2003;Dogan and Nur, 2006) and cycling sheep (Ustuner et al, 2007).…”

Effect of barium selenate injections on fertility of Pirlak ewes subjected to estrus synchronization during non-breeding season

“…Especially after a 14 d MAP application, estrus began earlier than it did after an 11 d MAP application (P < 0.001). In a similar study, progesterone administration for 14 days was reported to have caused estrus sooner than progesterone treatment for 9 d or less (8).…”