Time Lapse Changes in the Ovarian Activity of Dairy Cows During the Postpartum Period Guided by Ultrasonography: A Pilot Study

Abstract

This study aimed to characterize the postpartum (pp) follicular development and the process of resumption of ovarian activity in dairy cows. Six multiparous lactating Holstein cows were kept and examined twice weekly using ultrasound from day 11-19 PP until the appearance of a large mature corpus luteum (CL). The results showed that four of six cows (66.66%) exhibited dominant follicles (DF >10 mm) within 2 weeks PP (day 11, 15, 15, 16) and one cow (16.6%) needed 3 weeks (day 19) to develop DF. While only one cow (16.6%) displayed a delay (30 days pp) in the appearance of DF. The shortest interval between calving to the beginning of 1st luteal formation was 15 days recorded for one cow and the longest interval was 57 days and recorded also for one cow. While, in the other 3 cows, 29, 33, 43 days were recorded as the interval from calving to formation of first luteal tissue. The development of cysts following anovulated follicles with the size of 19-20mm occurred in two cows (33.3%). The persistence of cysts was longer in larger size cysts compared with the smaller one. Spontaneous recovery of the smaller cyst was faster than the larger cyst (10 vs. 23 days). Altogether, results showed that of the ultrasound scanning can be used as a guide to follow up the ovarian activity during PP period and thereby, identifying the optimal therapeutical and managemental interference to solve any reproductive disorder and maintain standard fertility parameters within a dairy herd.