Postpartum Ovarian Resumption in Native Dairy Cows in Upper Egypt and their Relation to Oxidant Antioxidant Status

Abstract

The present study aimed to characterize the follicular pattern and ovarian resumption during the postpartum period in lactating dairy cows in Upper Egypt and study the impact of different components of the antioxidant system on follicular dynamics. Sixteen native dairy cows in their second lactation period were assigned for the current study. Cows were kept indoor and subjected to ultrasonographic examination and bled daily. Data regarding the change in the follicular dynamics and incidence of short cycles were collected and tabulated then statistically analyzed. Blood samples were used to determine nitric oxide (NO), Vitamin A, B-Carotene, Vitamin C and Vitamin E. results of the present study revealed that The first postpartum behavioral estrus observed 35-47 days (41.5 ± 1.86 days postpartum). The average postpartum days required for the animal to come in estrus in cows with transient CL was 44 ± 1.76 days and in cows without transient CL was 37 ± 1.18 days. In cows with transient corpus luteum, first ovulation was not accompanied by behavioral estrus (Quiet ovulation) at 23 ±1.02 days. Vit A, B-carotene, Vit E, NO, but not Vit C, increased significantly during the first observable postpartum heat in the studied cows and their level in the plasma correlated differently with the different classes of ovarian follicles. It is concluded that most antioxidants in the present study, except ascorbic acid, increases at the time of estrus and they are not affected by the day of postpartum period or the number and size of the dominant follicles. Short cycles are frequent in the postpartum cows (50% of cows had a short cycles in the present work). Follicular growth starts immediately-may be before the studied time-in postpartum dairy cows.