Bacterial taxonomic composition of the postpartum cow uterus and vagina prior to artificial insemination1

Abstract

The current study characterized the taxonomic composition of the uterine and vaginal bacterial communities during estrous synchronization up to timed artificial insemination (TAI). Postpartum beef cows (n = 68) were subjected to pre-synchronization step 21 d prior to TAI (day −21), followed by an industry standard 7 Day Co-Synch on day −9 and TAI on day 0. Uterine and vaginal flushes were collected on days −21, −9, and −2 of the protocol and pH was immediately recorded. Pregnancy was determined by transrectal ultrasound on day 30. Bacterial DNA was extracted and sequenced targeting the V1 to V3 hypervariable regions of the 16S rRNA bacterial gene. Results indicated 34 different phyla including 792 different genera present between the uterus and vagina. Many differences in the relative abundance of bacterial phyla and genera occurred between resulting pregnancy statuses and among protocol days (P < 0.05). At day −2, multiple genera were present in >1% abundance of nonpregnant cows but <1% abundance in pregnant cows (P < 0.05). Uterine pH increased in nonpregnant cows but decreased in pregnant cows (P > 0.05). Overall, our study indicates bacterial phyla and genera abundances shift over time and may potentially affect fertility by altering the reproductive tract environment.

Vaginal Microbiota Changes During Estrous Cycle in Dairy Heifers

“…Currently, there is a knowledge gap describing the effect of the estrous cycle on cattle vaginal microbiota. 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).…”

“…Uterine and vaginal cattle microbiota have been determined to contain higher diversity compared to human vaginal microbiota (4,10). Nevertheless, Firmicutes were observed to be frequent and abundant in both (5,11,12).…”

“…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.…”

Evaluation of Reproductive Tract Cytokines in Post-partum Beef Cows Relating to Reproductive Microbiota and Fertility Outcomes

“…It has been indicated that the immune system has a vital role in the clearance of uterine diseases, normal reproductive functions, and establishment and maintenance of pregnancy; however, few studies have investigated the reproductive tract immunological environment prior to breeding and the subsequent effect on fertility in beef cattle. Based on published data from the current study, the diversity of bacterial communities of the reproductive tract shifts throughout an estrus synchronization protocol (Ault et al, 2019a) and this is likely due to the taxonomic composition of the bacteria in the uterus and vagina (Ault et al, 2019b). Notably, the relative abundance of multiple genera of bacteria differed between resulting pregnant and non-pregnant cows (Ault et al, 2019b).…”

“…Based on published data from the current study, the diversity of bacterial communities of the reproductive tract shifts throughout an estrus synchronization protocol (Ault et al, 2019a) and this is likely due to the taxonomic composition of the bacteria in the uterus and vagina (Ault et al, 2019b). Notably, the relative abundance of multiple genera of bacteria differed between resulting pregnant and non-pregnant cows (Ault et al, 2019b). In the current report, the first objective was to evaluate the concentration of both pro-and antiinflammatory cytokines from uterine and vaginal flush samples throughout an estrus synchronization protocol to determine the potential effects of the immune environment on fertility.…”