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Abstract
The uterine condition of clinically normal postpartum Holstein-Friesian dairy cows
(n = 45) was evaluated once weekly (Weeks 3 to 7) by endometrial cytology, vaginal
mucus collection device (VMCD), vaginoscopy, and ultrasonography to establish a relationship
with postpartum resumption of ovulatory cycles. The time of first detection of the
corpus luteum (CL) by ultrasonography and plasma progesterone concentration >or=1
ng/mL was recorded. By 49 d postpartum, 78% of the cows (n=35) had resumed ovarian
function (CL group), whereas the remainder (n=10) had no CL (NCL group). There was
a positive correlation between VMCD score and presence of fluid in the uterus in cows
with a CL (P<0.01) during Week 3 postpartum but no significant correlation in cows
without a CL. Percentage of polymorphonuclear leukocytes (PMN%) was higher in the
NCL group (mean+/-SEM, 24.6+/-9.4%) than in the CL group (11.7+/-2.2%) during Week
5 postpartum (P<0.05). The PMN% (4.5+/-6.5%) and VMCD (0.5+/-0.5) scores during Week
5 in cows ovulating by Day 28 were lower (P<0.01) than the PMN% (15.0+/-14.3%) and
VMCD (1.1+/-0.9) scores in those ovulating by Day 49. In conclusion, higher PMN% at
5 wk postpartum was associated with delayed resumption of ovarian cyclicity in high-producing
dairy cows.