Different estrous induction methods during the non-breeding season in Kivircik ewes

Abstract

The efficiency of medroxyprogesterone acetate (MAP) sponges in combination with either pregnant mare serum gonadotrophin (PMSG) or cloprostenol (PGF<sub>2α</sub>) for inducing and synchronizing the estrous cycle in non-lactating Kivircik ewes was investigated during the natural non-breeding season. All ewes (n = 69) were treated with 60 mg MAP sponges for 12 days. In addition, each ewe received an intramuscular injection of either 1.5 ml sterile saline solution (n = 18); 125 μg PGF<sub>2α</sub> (n = 14); 500 IU PMSG (n = 18) or 500 IU PMSG and 125 μg PGF<sub>2α</sub> (n = 19), 48 h before the sponge removal. Cervical artificial insemination (AI) with diluted fresh semen was performed at a fixed time (48 and 60 h) following progestagen withdrawal. The different groups estrous response for the first 24 ± 6 h and within 120 h, time to onset and duration of the induced estrous, and pregnancy rate was found to be 36.2%, 81.6%, 41.7 ± 2.3 h, 29.6 ± 1.5 h, and 54.5%, respectively. There were significant differences between groups MAP and MAP/PGF<sub>2α</sub> and their with the two latter groups (MAP/PMSG, MAP/PMSG/PGF<sub>2α</sub>) in terms of the onset of induced estrous (P < 0.05) and between groups MAP and MAP/PGF<sub>2α</sub> in terms of the duration of induced estrous (P < 0.05) and between the first two groups (MAP, MAP/PGF<sub>2α</sub>) and the latter two groups (MAP/PMSG, MAP/PMSG/PGF<sub>2α</sub>) in terms of estrous response at the first 24 ± 6 h (P < 0.05). These results indicate that, the use of MAP/PMSG, rather than MAP or MAP/PGF<sub>2α</sub>, was effective in the attainment of early and compact induction and synchronization of estrous in non-lactating Kivircik ewes during the natural non-breeding season.