During pregnancy, ewes may encounter various stressors that can have significant effects on their well-being and the development of their offspring. These stressors include physiological, environmental, and psychological factors. This study aimed to investigate the effects of OLE supplementation (2% and 4%) and Nannochloropsis oculata (3%) on pregnant ewes' immune functions. This study was primarily focused on evaluating the lymphocyte transformation test (LTT) (as a measure of immune response), serum lipid peroxidation, and superoxide dismutase levels (as indicators of oxidative stress). The study was conducted on healthy pregnant ewes in their last trimester of gestation. The ewes were divided into different groups, including a control group and groups supplemented with OLE and N. oculata. Performance parameters such as body weight gain and feed conversion ratio (FCR) were measured. Blood samples were collected to assess lymphocyte transformation, lipid peroxidation, and superoxide dismutase levels. The results showed that supplementation with OLE and N. oculata improved the FCR in pregnant ewes, indicating enhanced feed conversion efficiency. Additionally, the supplements significantly increased lymphocyte transformation and reduced lipid peroxidation levels, indicating improved immune response and reduced oxidative stress. In conclusion, this study explored the effects of OLE and N. oculata supplementation on pregnant ewes' immune functions. The findings suggest that these supplements can improve immune response and reduce oxidative stress in pregnant ewes, potentially benefiting both the ewes and their offspring.