Pouya Dini

Effect of uterine lavage on neutrophil counts in postpartum dairy cows

Subclinical endometritis affects approximately 30% of lactating dairy cows, causing significant economic losses to the dairy industry. Yet, there is no efficient treatment available for this condition. The present study examines the effect of uterine lavage in clinically normal cows with sterile saline solution at 30 days in milk (DIM) on the percentage of polymorphonuclear cells (PMNs) detected with endometrial cytology as an indicator of subclinical endometritis. It was hypothesized uterine lavage would be a technique to reduce the number of PMNs in the uterus, and hence be beneficial for cows affected by subclinical endometritis. Cytology samples were taken by low-volume flushing from 50 Holstein Friesian cows on 30 and 40 DIM. On Day 30, cows were clinically examined and randomly assigned into a treatment and control group. In the treatment group, the cytology sampling on Day 30 was immediately followed by uterine lavage with 500-600 mL of sterile physiological saline (35-40°C). Cytology sampling was repeated in all cows at 40 DIM. Lactation numbers >2, peripheral progesterone concentrations >1 ng/mL and uterine lavage at 30 DIM all were significantly associated with lesser PMN percentages at 40 DIM (P=0.0041; 0.0187 and 0.0043, respectively). Uterine lavage might, therefore, be a useful and practical method to decrease the number of PMNs in the uterus of cattle. Results from the current study can be used as preliminary data for designing in depth therapeutic protocols for treatment of subclinical endometritis in cattle.

Prevalence of cytological endometritis and effect on pregnancy outcomes at the time of insemination in nulliparous dairy heifers

The objectives of the present study were to assess the prevalence of cytological endometritis (CYTO) at the time of artificial insemination (AI) and its effect on pregnancy outcomes in nulliparous dairy heifers. In total, 512 endometrial cytology samples were taken during AI from 351 nulliparous Holstein-Friesian heifers using cytotape (a 1.5-cm piece of paper tape rolled on the top of an AI catheter covered with a double guard sheet). After sampling, the top of the AI catheter was gently rolled onto a glass slide, air-dried, and stained using Diff-Quick (Fisher Diagnostics, Newark, DE). For each slide, 300 nucleated cells were counted, and the polymorphonuclear cell ratio (% PMN) was assessed at 400× magnification. We constructed a receiver operating characteristic curve to find the cutoff point at which sensitivity and specificity (% PMN) affected pregnancy outcomes. The receiver operating characteristic curve revealed that the threshold level for diagnosing CYTO in nulliparous dairy heifers was 1% PMN. An insemination was considered successful when pregnancy was confirmed by rectal palpation at least 45d post-AI. Heifers were considered not pregnant when they received a subsequent insemination or were diagnosed empty by rectal palpation. We built multilevel generalized mixed-effect models to test factors affecting pregnancy outcomes and the occurrence of CYTO at AI. We excluded 16 samples harvested from 12 heifers due to poor sample quality or unavailability of reproductive data. Of the 496 AI samples, the prevalence of CYTO at AI was 7.86% (n=39). The conception rate was 62.8% (n=287) in CYTO-negative samples (n=457) and 38.46% (n=15) in CYTO-positive samples. Risk factors for non-pregnancy were a previous AI (odds ratio 2.96; 95% confidence interval: 1.21-7.26) and the interaction between CYTO and previous AI. The only risk factor identified as being associated with the occurrence of CYTO was a previous AI (odds ratio 4.7; 95% confidence interval: 2.15-10.34). The performance of unsuccessful inseminations significantly affects reproductive outcomes in subsequent AI and may lead to CYTO in nulliparous dairy heifers.