163 Assessment of the Methanogenic Archaeal Communities Throughout the Gastrointestinal Tract in Beef Cattle with Different Breeds
Bibliographic record
Abstract
Abstract Methane mitigation in ruminants is important to reduce greenhouse gas emissions and enhance feed utilization. Methanogenic archaea inhabit the gastrointestinal tract (GIT) of ruminants where they utilize H2 reducing equivalents formed by other microbiota (i.e., bacteria, fungi, and protozoa) to reduce CO2 to methane. This study aimed to assess methanogens in the GIT of beef cattle and evaluate the influence of gut regions and cattle breeds on methanogenic ecology. Digesta were collected from six gut regions (rumen, duodenum, jejunum, ileum, colon, rectum) in forty-two beef steers representing three breeds (Angus n=13, Charolais n=14, Kinsella composite hybrid n=15). Methanogens were characterized using 16S rRNA gene amplicon sequencing with methanogen-specific primers and analyzed using RIM-DB with QIIME2. Total methanogens were quantified using qPCR with universal methanogen primers. Gut region and breed effects were assessed using the non-parametric Kruskal-Wallis test. Estimation of methanogenic populations showed a region effect (P < 0.05), with the highest copy number observed in the rumen and the lowest in the duodenum and jejunum. Ten methanogenic species were identified (with a relative abundance ≥ 0.01% in ≥ 50% of individuals per breed) throughout the GIT with Methanobrevibacter ruminantium (predominant in all regions), Methanobrevibacter gottschalkii, and Methanosphaera sp. ISO3-F5 observed in all regions and in all breeds. Divergent methanogenic compositions were observed among gut regions (P < 0.05) and breed-specific species were identified (e.g., Methanobacterium bryantii in the colon of Charolais). The alpha-diversity index (Chao1) varied among gut regions (P < 0.05), and rumen showed the highest richness over other gut regions. Breed affected the alpha-diversity where Angus was distinct from other breeds (P < 0.05). These results revealed that methanogens in the GIT are region-dependent and breed-specific, highlighting the importance of taking cattle breed and total-tract ecology into consideration to understand the role of methanogens in the GIT.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".