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

Abstract

ABSTRACT. The efficiency of medroxyprogesterone acetate (MAP) sponges or norgestomet ear implants (half or entire) for synchronizing and inducing the estrous cycle in non-lactating Kivircik ewes was investigated during the natural non-breeding period. Ewes were treated for 11 days either with 60 mg MAP sponges (group 1, n=27) or with 1.5 mg norgestomet (group 2, n=25) or with 3 mg norgestomet (group 3, n=27) ear implants. In addition, each ewe received an intramuscular injection of 500 IU of equine chorionic gonadotropin (eCG) and 125 µg cloprostenol (PGF2α), 48 h prior to progestagen removal. Double Cervical Artificial Insemination (AI) with diluted fresh semen was performed at a fixed time (36 and 48 h) following progestagen withdrawal. Mean values for estrous detection rates at the first 12 ± 6 h and within 72 h, the time from progestagen removal to the onset of estrous, the duration of the induced estrous and pregnancy rate were found to be 46.8%, 86.1%, 26.1 ± 7.3 h, 27.0 ± 10.7 h and 27.8%, respectively. There were significant differences between groups 2 and 3 in the time of induced estrous onset (P<0.05). These results indicate that, each of the three protocols was equally efficient in inducing and synchronizing estrus in non-lactating Kivircik ewes during the natural non-breeding period.

Effect of pre-synchronisation with progestogen and eCG on reproductive activity in synchronised ewes during anoestrous season

“…There was considerable variation in the pregnancy rate after the cervical insemination in ewes in previous studies (Zeleke et al 2005;Dogan and Nur 2006;Ustuner et al 2007;Masoudi et al 2017;Dogan et al 2018). Although all cervical inseminations were conducted in the same breed in the previous and current studies, the pregnancy rates varied on the synchronisation protocol, time of the FTAI, nutritional status, and management status (Menchaca and Rubianes 2004;Scaramuzzi et al 2006;Dogan et al 2018).…”

“…There was considerable variation in the pregnancy rate after the cervical insemination in ewes in previous studies (Zeleke et al 2005;Dogan and Nur 2006;Ustuner et al 2007;Masoudi et al 2017;Dogan et al 2018). Although all cervical inseminations were conducted in the same breed in the previous and current studies, the pregnancy rates varied on the synchronisation protocol, time of the FTAI, nutritional status, and management status (Menchaca and Rubianes 2004;Scaramuzzi et al 2006;Dogan et al 2018). While the pregnancy rate was reported as 72.3% after cervical insemination with 200 × 10 6 spermatozoa between 53-55 h after the sponge removal during the transition period in Dorper ewes (Zeleke et al 2005), the pregnancy rate was determined as 33.3% after two cervical inseminations with 250 × 10 6 spermatozoa at 40 h and 60 h following the sponge removal during the breeding season in Awasi ewes (Ustuner et al 2007).…”

Effectiveness of a low-dose Norgestomet ear implant in short-term protocols to induce estrus in ewes during the non-breeding season in Brazil.

“…Figure 2 -Estrus response (%) and pregnancy rate (%) using an intravaginal progesterone device (G-nP4) or ear implant (G-NOR). and entire Norgestomet ear implants were equally efficient in synchronizing and inducting estrus in ewes during natural anestrus (Dogan et al, 2018). In ewes, Norgestomet ear implants were successfully reused to synchronize estrus in Texel (Bragança and Rocha, 2018).…”

“…The use of Norgestomet implants inserted subcutaneously in the back of the ear has been reported to improve fertility in ewes (Castilho et al, 2007;Awel et al, 2009;Garoussi et al, 2012;Santos and Barcelos, 2012;Dogan et al, 2018). However, the use of commercial doses of Norgestomet in ewes is still in the incipient stages compared with the use of other devices, and further studies are necessary to evaluate its effects on animal reproduction.…”

“…However, the use of commercial doses of Norgestomet in ewes is still in the incipient stages compared with the use of other devices, and further studies are necessary to evaluate its effects on animal reproduction. Half and entire Norgestomet ear implants were equally efficient to synchronize and induce estrus in ewes during natural anestrous (Dogan et al, 2018). Nevertheless, there is no study about estrus induction using less than a half ear implant.…”