Ultrasonographic evaluation for the effect of postpartal ovarian activity and uterine involution on subsequent reproductive performance of dairy cows [electronic resource].

Includes references.

The objective of this study was to test the hypothesis that presence of dominant follicle in the ovary ipsilateral to the previously gravid uterine horn (PGH), between 2 and 4 weeks postpartum, improves subsequent reproductive performance. A total 28 Holstein-Fresian lactating cows in the farm of the Faculty of veterinary medicine Assiut university were examined using transrectal ultrasonography twice weekly between second and fourth week postpartum. The number of follicles ( ~ 5 mm diameter) in the ovary ipsilateral to the PGH was fewer than that in the ovary contralateral to the PGH (0.70:f: 0.08 vs. 1.04:f: 0.09 , P < 0.001). There were fewer cows with a dominant follicle (~ 10 mm diameter) in the ovary ipsilateral to the PGH compared with those with dominant follicles in the contralateral ovary (25.0 %, n= 7, vs. 53.69%, n= 15, P < 0.05). In addition, there were fewer cows with a corpus luteum in the ovary ipsilateral to the PGH compared with those having corpora lutea in the contralateral ovary (4/28, 14.3%) vs. (11/28, 39.3%, P < 0.001). Days to the 1 st service and number of service per conception in the group which had dominant follicles in the ovary ipsilateral to the PGH (n= 7) and animals without such follicles (n= 21) were 52.73 :f: 6.4, 1.97:f: 0.24 and 79.78:f: 3.4, 1.87:f: 0.11 respectively. Days open in the animals with ovarian activity in either ovaries (n= 22) were 97.04 :f: 8.4 days and in animals without ovarian activity (n= 6) were 122.2± 7.8 days (P < 0.01). The calving to conception interval was shorter in those animals with a smaller diameter of the PGH « 60 mm diameter was 95.8 :f: 5.3 days and> 60 mm diameter was 122. 3:f: 1.09 days, P < 0.01). This observation raises an interesting question: How does this follicle affect subsequent fertility - does the follicle exert a local influence on the uterus, or vice versa?

Summary in Arabic.