title: The influence of ovarian activity and uterine involution determined by ultrasonography on subsequent reproductive performance of dairy cows.
abstract: The objective of this study was to test the hypothesis that a follicle >8 mm diameter in the ovary ipsilateral to the previously gravid uterine horn (PGUH), between 14 and 28 days postpartum, improves subsequent reproductive performance. Lactating Holstein-Friesian cows (n=284) in 3 commercial herds were examined using transrectal ultrasonography once between 14 and 28 days postpartum to determine associations between uterine and ovarian measurements and subsequent fertility. There were fewer cows with a corpus luteum in the ovary ipsilateral to the PGUH compared with the contralateral ovary (16.9% vs. 37.0%; P<0.001). In addition, in the ovary ipsilateral to the PGUH there were fewer follicles >5 mm diameter (mean +/- SEM; 0.69 +/- 0.06 vs. 1.02 +/- 0.06; P<0.001) and fewer animals with a follicle >8 mm diameter (26.1% vs. 49.6%; P<0.001). These differences between the ovaries ipsilateral or contralateral to the PGUH declined with increasing time between 14 and 28 days postpartum. The presence of a purulent vaginal discharge decreased the number of animals with a corpus luteum in the ovary contralateral to the PGUH (45/143 vs. 60/141; P<0.05), but not in the ovary ipsilateral to the PGUH. The presence of a follicle >8 mm diameter in the ovary ipsilateral to the PGUH was associated with a shorter calving to conception interval compared with animals without such a follicle (99.0 +/- 5.6 days, n=74, vs. 112.8 +/- 4.4 days, n=210; P<0.05). These observations raise an intriguing issue: how does this follicle affect subsequent fertility--does the follicle exert a local influence on the uterus, or vice versa?
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, North Mymms, Hatfield, UK.
authors.forename: I M
authors.initials: IM
authors.lastname: Sheldon
authors.forename: D E
authors.initials: DE
authors.lastname: Noakes
authors.forename: H
authors.initials: H
authors.lastname: Dobson
mesh_terms: D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology*; D003612:Dairying; D005260:Female; D005298:Fertility; D006080:Ovarian Follicle / Q000000981:diagnostic imaging; D010053:Ovary / Q000502:physiology*; D049590:Postpartum Period; D011247:Pregnancy; D012098:Reproduction; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging*