Pregnancy-associated glycoproteins (PAGs) and progesterone concentrations in Holstein heifers following two methods of estrus syncronization

Abstract

Pregnancy-associated glycoproteins (PAGs) and progesterone concentrations were assessed in Holstein heifers 28 days post-insemination, following estrus synchronization with either a double prostaglandin (PG) injection or the ovsynch protocol. Animals between 15 and 20 months of age, with a 3-3.5 BCS, were randomly assigned to three groups: Heifers in the control group (n = 70) were monitored for estrus behaviour for 21 days and inseminated when detected in standing heat; Estrus of heifers in the Ovsynch group (n = 70)) was synchronized following the Ovsynch protocol, and timed artificial insemination was performed 16 h after the completion of treatment; Animals in the PG group (n = 70) received two prostaglandin-F2α injections 11 days apart, were monitored for estrus behaviour for 2-5 days following the last injection, and inseminated when in heat. Serum PAGs and progesterone concentrations were measured in pregnant heifers (control group n = 25; ovsynch group n = 22; PG group n = 21) on day 28 after artificial insemination (AI). Mean serum PAGs concentrations (OD: optical density) were similar between groups (control = 3.37 ± 0.148, Ovsynch = 3.21 ± 0.136, and PG = 3.34 ± 0.143; p > 0.05). However, serum progesterone concentrations were found to be lower in the ovsynch group (4.70 ± 0.17 ng/mL) when compared to the PG (5.34 ± 0.13 ng/mL) or the control (5.37 ± 0.08 ng/mL) groups (p < 0.001). There was no correlation between serum PAGs and progesterone levels at day 28 post-insemination, or between early pregnancy PAGs concentrations and fetal death rates. Further research, including multiple sampling time points throughout gestation, after estrus synchronization protocols is warranted, to determine if there are associated temporal changes in PAGs and progesterone profiles that could impact reproductive parameters in dairy heifers.

Serum pregnancy–associated glycoprotein profiles during early gestation in Karya and Konya Merino sheep

“…Pregnant and non‐pregnant ewes can be identified with a high accuracy as of day 24 of gestation, based on the measurement of serum PAGs levels by the ELISA test as a more reliable alternative to the RIA method (El Amiri et al., 2007 ; Redden & Passavant, 2013 ). Today, commercial PAG‐ELISA pregnancy diagnosis test kits are available for use in cattle (Akkose et al., 2019 ; Akköse, 2023 ; Szenci, 2021 ) but have not been validated for specific use in sheep yet. However, the high level of similarity between the molecular structure of bovine and ovine PAGs (Xie et al., 1991 ) allows the safe use of bovine PAG‐ELISA tests in sheep (Akköse, 2020 ; Chaves et al., 2020 ; de Miranda e Silva Chaves et al., 2017 ; Roberts et al., 2019 ; Steckeler et al., 2018 ).…”