Effect of the method of estrus synchronization and PMSG dosage on estrus and twinning in Ethiopian Menze sheep

Mature, cyclic Ethiopian Menze ewes (n = 72) were used in this study. They were divided into 6 equal groups in a 2x3 factorial experimental design. Estrus and ovulation were synchronized in all ewes using either 2 dosages of prostaglandin F2 alpha 12 days apart (n = 36) or intravaginal progestogen sponges for an equal length of time (n = 36). At sponge removal or at the second prostaglandin injection, equal groups of ewes were injected with either 0, 200, or 300 IU of PMSG. Prostaglandin-synchronized ewes exhibit estrus significantly earlier (P = 0.025) than the progestogen-synchrcnized group. Although PMSG treatment increased twinning rates and therefore total number of lambs born, the differences between groups did not reach significant levels (P>0.10).