the influence of ovarian activity and uterine involution determined by ultrasonography on subsequent reproductive performance of dairy cows

摘要

The objective of this study was to test the hypothesis that a follicle >8 mm diameter m the ovary ipsilateral to the previously gray'id uterine horn (PGUH), between 14 and 28 days postpartum, tmproves 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 ammals with a follicle >8 mm diameter (26.1% vs. 49.6%; P<0.001). These differences between the ovaries ipsilateral or conttalateral to the PGUH declined with increasing ume between 14 and 28 days postpartum. The presence of a purulent vaginal discharge dccreased 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 m 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?