文摘
To study ovarian responses to long-term intrauterine infusions of Trueperella pyogenes (T.?pyogenes), 12 nonlacting Holstein cows were transcervically infused with 10 mL of a bacterial solution (8-19 ¡Á 108 colony-forming units/mL), and the uteri of another four cows (control) were similarly infused with sterile physiological saline. Infusions were done six times, every 3 days from Days 3 to 18 (Day 0 = day of spontaneous ovulation). Development of ovarian follicles and the CL were monitored with transrectal, real-time ultrasonography. In five of the experimentally infected cows (group A), the CL, which developed after Day 0, regressed without maturing, and the first dominant follicle (DF) ovulated (mean ¡À SEM interovulatory interval, 8.6 ¡À 0.5 days). In group A, plasma 13,14-dihydro-15-keto-PGF2¦Á (PGFM) concentrations rose sharply on Day 6, but plasma progesterone concentrations did not increase substantially (as in the control) and were maintained at approximately 2.5 ng/mL after the first DF ovulated. In seven of the 12?infected cows (group B), the developing CL which formed after Day 0 matured and the second DF ovulated. However, the CL lifespan was shorter (P < 0.01) and the second DF ovulated earlier than in control (interovulatory interval, 16.0 ¡À 0.4 days and 22.3 ¡À 1.9 days; P < 0.01). Although there was no sharp increase in PGFM in group B, it tended to be?high between Days 11 and 18. In conclusion, long-term, intrauterine infusions of T.?pyogenes caused the CL to regress prematurely or to have a somewhat shorter lifespan because of release of endogenous PGF2¦Á.