This study was carried out to monitor serum cortisol level in pregnant ewes and comparing it with the non-pregnant values. Also, cortisol levels were monitored in single-fetus bearing and twin-fetus bearing ewes. This study was carried out during the breeding season on 31 pregnant and 5 non-pregnant ewes. Pregnancy and fetal numbers were determined through transrectal ultrasonography. Blood samples were collected every two weeks starting at day 30 of pregnancy until day 135 of pregnancy. Blood samples were collected in parallel from non-pregnant ewes as a control group. Cortisol was measured using ELISA.The results showed that serum cortisol levels increased gradually in pregnant ewes until day 90 of pregnancy reaching the highest level at day 135. Serum cortisol level was 4.26 ± 0.16 ng/ml at day 135 of pregnancy, while its level in non-pregnant ewes was 1.85 ± 0.15 ng/ml. Cortisol level was little bit higher in primiparous than pluriparous ewes, however, the difference was not significant. Regarding the effect of fetal number on cortisol level, twin-fetus bearing primiparous ewes had the significantly highest level. In addition, twin-fetus pulriparous ewes had a higher cortisol level than single-fetus bearing ewes.
In conclusion, cortisol level increased gradually during pregnancy until day 90 reaching the highest level at day 135 of pregnancy. In addition, cortisol level was significantly higher in twin-fetus bearing ewes than single-fetus bearing ewes. This indicates that twinning increases stress on the pregnant ewes especially in primipara which need more care and attention.