Maternal Undernutrition Effect on Pregnancy-Associated Glycoprotein (PAG) Concentration in Sheep Carrying Single and Multiple Fetuses

To the best of our knowledge, no studies in the literature have reported on the relationship between the pregnancy-associated glycoprotein (PAG) concentration and undernutrition during pregnancy in sheep. Therefore, the aim of this study was to investigate the effects of undernutrition on the blood concentration of PAGs in pregnant ewes carrying single and multiple fetuses, undergoing either dietary energy restriction or receiving 100% of their energy requirements during the period of maximal placenta growth. From d 24 to 100 of pregnancy, the ewes were fed ryegrass hay and two different iso-proteic concentrates, fulfilling either 100% of the ewes’ energy requirements (control group; n = 30, 14 singleton pregnancies, 16 multiple pregnancies) or only 50% (feed-restricted group; n = 29; 11 singleton pregnancies, 18 multiple pregnancies). Blood samples were collected from all the ewes the day before intravaginal sponge insertion (T0) and, thereafter, every 30 days starting from d 24 of gestation (T1) until d 30 after parturition (T6), to determine the PAG, progesterone, NEFA, total protein, and glucose concentrations. Our results showed that PAG concentrations are not only influenced by the number of fetuses, but also by the ewe’s diet. In particular, the PAG marginal means were higher in the feed-restricted group than in the control group (7.8 ± 0.6 and 10.8 ± 0.9 ng/mL for the control and feed-restricted groups, respectively; p = 0.040). This finding confirms that a dietary restriction between d 24 and d 100 of gestation leads to a growth in placental functions as inferred from the increase in the concentration of the PAG levels. Therefore, the measurement of PAG concentrations, in addition to serving as a marker of pregnancy, can also serve as a marker of placental functionality.