h: 0px; "> The present study aimed to determine the effect of adding plant oils; extra virgin olive oil (EVOO), sunflower and soybean to animal feed on serum estradiol (E2) and progesterone (P4) levels, histological structure of ovaries and in vitro maturation of oocytes (IVM). A total of 60 mature female Albino rats were used. Animals were divided equally into 5 groups; control group (received standard diet), group II (received EVOO), group III (received sunflower oil), group IV (received soybean oil) and group VI (received oil mixture which consist of sunflower and soybean oils). After 6 weeks of feeding oil addited diet, blood samples were collected from all rats throughout the different stages of estrous cycle. Sera were used for determination of serum E2 and P4 levels. Only females that were not in estrus were scarified after the last blood sample collection, ovaries were harvested for histopathological examination and for in vitro maturation. Results showed that none of oils led to ovarian changes except soybean oil and oil mixture, cause congestion of some ovarian blood vessels. It was
also noted that the hormonal pattern didn't differ significantly among different treatments within the same stage of the cycle, except for the group received oil mixture where E2 and P4 levels decreased significantly (P < 0.05) during metestrus and diestrus phases, respectively. In the treated groups, the highest significant (P < 0.05) oocyte recovery rate (RR) (5.43 ± 0.23% and 4.41± 0.13%) and maturation rate (MR) (79.17 ± 2.03% and 73.43 ± 1.97%) were attained after application of EVOO followed by sunflower oil, respectively. While the lowest values were calculated with the soybean oil and oil mixture (3.83 ± 0.13 % and 2.50 ± 0.16 %) and (68.18 ± 2.29 % and 62.50 ± 2.23 %), respectively. It could be concluded that EVOO as well as sunflower oil have a beneficial influence on ovarian functional performance, retrieval of high number of good quality oocytes and raise oocyte maturation.