Association between fecal methanogen species with methane production and grazed forage intake of beef heifers classified for residual feed intake under drylot conditions
Bibliographic record
Abstract
Reduction in greenhouse gas emission from beef production is essential to the survival of the beef industry from environmental and social-economic perspectives. There are different systems available to measure methane from animals, but they are expensive, not easily accessible, and not suitable for large-scale methane measurements on the farm. Therefore exploring indicator traits, which are easy to measure, cost-effective, and suitable for large-scale measurement, are recommended. The objectives of this study were to examine the diversity of fecal methanogen profile among efficient and inefficient beef heifers on pasture and investigate methanogen profile as a possible proxy to predict methane emission in beef cattle consuming a forage diet. Forty pregnant (1st trimester) heifers previously classified for postweaning residual feed intake adjusted for off-test back fat (RFIfat; 20 high and 20 low) were included in this study. To determine individual pasture grazing intake, heifers were dosed with 1 kg of C32 labeled pellets once per day from Day 0 to Day 12, and fecal samples were collected twice daily from Day 8 to Day 15. Fecal samples from Days 8, 10, and 12 were analyzed for their methanogen profile. Animals were monitored individually for methane and carbon dioxide production using a GreenFeed Emissions Monitoring system. Total methanogen population and methanogenic community diversity of fecal samples were not different (P > 0.1) between low and high RFIfat groups, as measured by quantitative PCR and α- and β-diversity indices. However, both groups had a different methanogen profile; the relative abundance of Methanobrevibacter wolinii and relatives were higher (P < 0.002), while that of Methanosphaera species ISO3-F5 was lower (P < 0.01) in low RFIfat cattle compared to the high RFIfat group. We also demonstrated that fecal methanogen profiles may be a useful proxy in predicting daily methane and carbon dioxide emissions with an adjusted R2 of 0.53 and 0.33, respectively, for low RFIfat heifers and 0.46 and 0.57, respectively, for the high RFIfat group.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".