Uterine and vaginal bacterial community diversity prior to artificial insemination between pregnant and nonpregnant postpartum cows1

Abstract

The present study evaluated the bovine vaginal and uterine bacterial community diversity and its relationship to fertility. Postpartum beef cows (n = 68) were synchronized beginning on day −21 and ending with timed artificial insemination (TAI) on day 0. Pregnancy was diagnosed 30 d after TAI. Uterine and vaginal flushes were collected on day −21, −9, and −2 for bacterial DNA extraction to sequence the V1 to V3 hypervariable regions of the 16S rRNA gene. Results indicated a decrease in the number of bacterial species over time in the uterus of resulting pregnant and nonpregnant beef cows (P < 0.0001). Principal coordinate analyses (PCoA) depicted clustering of samples, indicating closely related bacterial communities, by day in the uterus and vagina (P < 0.0001). At day −2, uterine samples from nonpregnant and pregnant animals clustered separately (P < 0.0001), with nonpregnant animal samples clustering tightly together. Overall, the current study suggests the shift in the reproductive bacterial communities’ diversity and phylogenetic relationship leading up to the time of breeding may contribute to successful pregnancy establishment.

Vaginal Microbiota Changes During Estrous Cycle in Dairy Heifers

“…The genus Lactobacillus was found at a low relative abundance through the estrous cycle. These results were in agreement with previous studies that used culture-independent methods to characterize the vaginal microbiota of ruminants (4,14). Here, differences in relative abundance throughout the estrous cycle were detected for 32 genera and 3 families.…”

“…These authors have suggested an intestinal origin for the vaginal microbes, explained by the anatomical proximity (5,12). Ault and colleagues have previously described differences in the abundance of Tenericutes and Acidobacteria in pregnant and non-pregnant post-partum cows with a higher abundance of these phyla in non-pregnant cows (14). The absence or lower abundance of the Tenericutes phylum in previous studies compared with the present study could be related to differences in breed, geographic location, diet, and age, among others (5,12).…”

“…Ault and colleagues have described that the diversity of the microbiota during luteal phase significantly decreases as the reproductive tract prepares for pregnancy (10). The same authors described differences in Verrucomicrobia, Fusobacteria, and Tenericutes abundances between pregnant and non-pregnant cows (14). However, the diversity and composition of the microbiota during estrus (high concentration of estrogen) was not evaluated in these studies.…”

“…Nevertheless, Firmicutes were observed to be frequent and abundant in both (5,11,12). Despite the efforts that have been done to study the vaginal microbiota of dairy and beef cows (5,10,13,14), there is scarce knowledge on the vaginal microbiota of healthy heifers (12). Understanding the influence of the estrous cycle on the reproductive microbiota is of the most importance since it will allow the identification of new therapeutic antibiotic-free strategies to treat infections during reproduction protocols.…”

Use of Probiotics in Intravaginal Sponges in Sheep: A Pilot Study

“…Enterobacteriaceae in the vaginal tract may come from the gastrointestinal tract due to the anatomy of the ewe's reproductive tract as described by other authors in the cow [25,26]. Here, we described that LAB CFUs are very scarce in the ewe's vagina independently of the time evaluated as previous studies reported using culture-independent method (16S rRNA sequencing) in ruminants [20,27]. Bacterial communities studied (Enterobacteriaceae and LAB) were highly fluctuating over time and between animals, as previously described by other authors in bovine uterus [28,29].…”