The values of luteal blood flow (LBF), total corpus luteum (CL) area (TAR), and progesterone (P4), during and after OvSynch (OvS) protocol in comfort (CP; n = 40) and hot periods (HP; n = 40) were compared. We investigated how low and high P4 values obtained before the application affected the parameters above during CP and HP periods. Blood samples were collected before the OvS application on day 0 (OVSd0), day 9 (OeG), and day 18 (9th day after OeG: OvSd9). The P4 (ng/mL) values of the animals exhibiting dominant follicles were between 0.12–0.82 in HC and 0.1–0.88 in CP (P4-2: 4.36–4.38 and P4-3: ≥7.36 ng/mL). The LBF values were measured on days 7 (OvSd7) and 9 (OvSd9) after the OeG. The P4 mean values at day 0 (OvSd0) were classified as low (P4-1), medium (P4-2), and high (P4-3). The LBF and the TAR values in the P4-2 and P4-3 on OeG day 9 were higher than in HP (p < 0.05; 0.001), but there was no significant difference in the P4-1. In conclusion, when the OvS program was initiated with low P4 values, no difference was observed between HP and CP in terms of LBF values; however, when the program was started with high P4 values, there were significant increases in LBF and TAR values in the CP compared to the HP.

The study groups (n = 39) included ewes with ongoing pregnancy (P+; n = 19), with fetal death (FD; n = 12), and that were not pregnant (P−; n = 8). Blood samples were taken on days 10, 20, 30, 40, 60, 80, and 150 post-mating. Ultrasonography (USG) controls started on day 30. The P₄ concentrations differed significantly between P+ and P− on all days (p < 0.001). Regarding AMH concentrations, a significant difference was observed between P+ and P− on day 30. P₄ increased significantly from day 60 to 80 and remained elevated until day 150 in P+, while remaining basal in P−. In FD and P− groups, P₄ reached its lowest concentrations. A rapid decrease in P₄ was observed in P− from day 20 onwards. A statistically significant difference in P₄ was also noted between P+ and FD. Additionally, P₄ concentrations differed between singleton and twin pregnancies, especially on days 20 and 40. Statistically significant differences in AMH were found between P+ and FD on days 10, 20, and 30. In P+ sheep, P₄, AMH, and Hp concentrations varied by season. A significant relationship was found between AMH and Hp concentrations and body weight. In conclusion, P₄ stands out as the primary marker for distinguishing pregnancy status and detecting embryonic loss, while AMH provides complementary support, particularly in identifying fetal death. Seasonal changes were reflected across P₄, AMH, and Hp concentrations, with AMH and Hp also showing significant associations with BW.