Méndez MM, Joel Hernández Cerón, Pacheco RNO, Porras AA

Language: English/Spanish
References: 10
Page: 369-371
PDF size: 31.52 Kb.

ABSTRACT

The objective of this study was to determine if progestagens (either melengestrol acetate (MGA) or norgestomet) based synchronization treatments either, with or without estrogens can induce estrous behavior in ovariectomized ewes. Ten ovariectomized ewes were subjected to 4 different treatments twice with a 20 day interval between them. One sheep was removed from the study after its third treatment. treatment 1 received 0.22 mg of MGA mixed in the daily feed for 9 days; Treatment 2 received MGA as for treatment 1 plus 0.5 mg of estradiol cipionate im at the beginning of the treatment; treatment 3 received an ear implant with 3mg of norgestomet for 9 days. Treatment 4 received a norgestomet implant plus 1 ml of a solution containing 2.5 mg of estradiol valerate and 1.5 mg of norgestomet at the beginning of the treatment. Estrous behaviour was assessed 3 times a day during the 6 days that followed progestagen withdrawal. The onset of estrous was considered when mounting was accepted. In treatment 2 (MGA+estradiol), estrous was observed in 52% of the ewes at 68 ± 32.7 hours (media ±standard deviation). In Treatment 4 (norgestomet+estradiol) estrous was observed in 88% of the sheep at 36.7 ± 19.2 hours. In Treatments 1 (MGA) and 3, (norgestomet) only 10% showed estrous behavior at 37 ± 7.0 and 24 ± 0 hours, respectively. It is concluded that synchronization of estrous using progestagens combined with an initial estrogen injection induces estrous behavior in ovariectomized ewes.

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