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(2 alpha)) 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 mu g PGF(2 alpha) (n = 14); 500 IU PMSG (n = 18) or 500 IU PMSG and 125 mu g PGF2 alpha (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(2 alpha) and their with the two latter groups (MAP/PMSG, MAP/PMSG/PGF(2 alpha)) in terms of the onset of induced estrous (P < 0.05) and between groups MAP and MAP/PGF2a in terms of the duration of induced estrous (P < 0.05) and between the first two groups ( MAP, MAP/PGF2a) and the latter two groups (MAP/PMSG, MAP/PMSG/PGF2 alpha) 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/PGF2 alpha, 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.