The influence of fetal sex and litter size on pregnancy-associated glycoprotein concentration at the end of the embryonic period in Hasak ewes

In sheep flocks, reproductive efficiency is a fundamental factor for economic profitability and a direct result of reproductive management. The management of pregnant ewes involves the diagnosis of pregnancy and the determination of the number of conceptions in utero to enable breeders to make informed decisions for the future management of the flock. The aim of this study was to investigate whether the concentration of pregnancy-associated glycoprotein (PAG) in plasma on day 35 of pregnancy can be used to predict the number and sex of conceptions in Hasak ewes. For this purpose, a total of 75 pregnant Hasak ewes aged 2-7 years kept under identical conditions were randomly selected. The pregnancy status and number of conceptions of the ewes were determined on day 35 after mating using a transrectal ultrasound technique with a 7.5 MHz linear probe. Immediately after pregnancy diagnosis, blood samples were taken from the jugular vein of all selected ewes and the plasma samples were separated. After a healthy pregnancy and lambing, the ewes were divided into five groups based on the number and sex of lambs born: singleton male lambing ewes (SM group, n=27), singleton female lambing ewes (SF group, n=27), twin male lambing ewes (TM group, n=8), twin female lambing ewes (TF group, n=7), one male and one female lambing ewes (TMF group, n=6). Plasma PAG concentrations were measured using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Data were analysed using an independent samples t-test and one-way ANOVA. The results showed that the number and sex of lambs born had no significant effect on plasma PAG concentrations measured on day 35 of pregnancy (p>0.05). In conclusion, plasma PAG concentration on day 35 of pregnancy is not a reliable predictor of the number or sex of lambs born in Hasak ewes.