Effect of eCG inclusion in a progesterone-based estrus synchronization protocol on plasma pregnancy-associated glycoprotein concentrations and lambing performance in sheep
Abstract
Progesterone (P4)-based estrus synchronization protocols are commonly used to improve reproductive performance in ewes. In this study, it was evaluated whether adding equine chorionic gonadotropin (eCG) to a P4 and prostaglandin F2α (PGF2α)-based protocol affects plasma pregnancy-associated glycoproteins (PAG) concentrations on day 35 of pregnancy and selected reproductive outcomes in Hasak ewes. Fifty ewes were synchronized with P4+PGF2α (n = 19) or P4+PGF2α+eCG (n = 31) protocols and then mated with fertile rams. Pregnancy was confirmed on day 35 post-mating by ultrasonography, and plasma samples were collected. After parturition, lambing data were recorded. PAG concentrations were measured via ELISA. The estrus-synchronization protocol did not significantly affect PAG concentrations on day 35 of pregnancy, the average lamb birth weight, or gestation length (p > 0.05). However, the lamb productivity and total birth weight were significantly higher in the P4+PGF2α+eCG protocol (p < 0.05). In this study, it was shown that the addition of eCG to a P4-based estrus synchronization protocol improved lambing performance; however, no effect on maternal PAG concentrations was observed on day 35 of gestation.
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