188 Characterization of the Vagino-Uterine Microbiota in Pregnant and Non-Pregnant Beef Cattle Using 16S Rrna Gene Sequencing and Culturing
Bibliographic record
Abstract
Abstract Emerging evidence suggests that urogenital microbiome-targeted approaches may provide a novel opportunity to reduce the incidence of reproductive failures in cattle. The objectives of this study were to: 1) characterize the vaginal and uterine microbiota between beef cattle that became pregnant via artificial insemination (AI) and those that did not; 2) identify differentially abundant taxa between pregnant and non-pregnant cattle; and 3) characterize the culturable fraction of the vaginal and uterine microbiota using extensive culturing. Vaginal and uterine swab samples were collected from two cohorts of Angus-crossbred cattle: mature cows (n =100) and heifers (n = 72, vaginal swab only) at the time of AI. At 35 days post-AI, pregnancy diagnoses were made via ultrasound. A subset of vaginal and uterine swabs from cows (27 non-pregnant and 31 pregnant) and heifers (26 non-pregnant and 33 pregnant) were selected and processed for microbiota assessment using 16S rRNA gene (V3-V4) sequencing. For culturing, a subset of cryopreserved vaginal and uterine swabs (128) were plated onto three different agar types and cultured, and isolates were identified by near-full length 16S rRNA gene sequencing. Sequencing results revealed 11 taxa that were more abundant in the vaginas of heifers that failed to become pregnant via AI than heifers that did become pregnant. While there was no significant difference in vaginal microbiota community structure (P = 0.21) between pregnant and non-pregnant cows, non-pregnant cows tended to have greater microbial richness and Shannon diversity (P ≤ 0.08) compared with pregnant cows. No differentially abundant taxa were detected in the vaginas of pregnant versus non-pregnant cows. Pregnant cows had a distinct uterine microbiota community structure (R2 = 0.032, P = 0.008) but similar alpha diversity (P > 0.1) compared with non-pregnant cows. Twenty-eight differentially abundant taxa were observed in the uterine microbiota between pregnant and non-pregnant groups, with 11 of them more abundant in pregnant cows. Methanobrevibacter ruminantium (archaea) and Fusobacterium necrophorum were among these 11 positive pregnancy-associated taxa. Although community structure was significantly different between the vagina and uterus, 277 “core taxa” (present in ≥ 80% of all samples) were shared between the two communities. A total of 733 bacterial isolates were recovered from vaginal (512) and uterine (221) swabs under aerobic (n = 363, 83 different species) and anaerobic (n = 370, 69 species) culturing. Potential pathogenic isolates within the Trueperella, Mannheimia and Histophilus genera were most exclusively identified from vaginal swabs. Only two Lactobacillus isolates were recovered. Overall, our results indicate that pregnancy-associated taxonomic signatures are present in the bovine uterine and vaginal microbiota. Among 39 pregnancy status-associated taxa, 41% were unclassified at the genus level, suggesting that shotgun metagenomics and culturomics are needed to identify and characterize the pregnancy-associated taxa in cattle.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".