PSXI-2 Evaluating the relationship between rumen microbial composition and divergent digestible fibre intake in beef heifers.
Bibliographic record
Abstract
Abstract This study aimed to examine the impact of selecting beef heifers for divergent digestible neutral detergent fibre (NDF) intake (DFI, g/kg BW0.75) on the composition of their rumen microbial communities. Sixteen rumen-cannulated Angus × Hereford heifers (584 ± 32.2 kg) were individually housed and fed four diets consecutively. Diets were fed ad libitum for 28-d per period (P) and consisted of: P1) 100% grass hay; P2) 100% mature alfalfa hay; P3) 90% dry rolled barley + 10% alfalfa hay; and P4) 90% dry rolled barley + 10% grass hay (DM basis). Heifers were selected from a group of 64 fed a high forage diet prior to this study and were classified as either high or low DFI (29.0 vs. 21.1 g/kg BW0.75, n = 8/treatment). Dry matter intake was recorded daily, and heifers were weighed on a weekly basis. Ruminal digesta samples were collected to assess total protozoa counts and speciation via optical microscopy for 2-d within each period, with collections made prior to and 6 h after feeding. Samples were also taken on d 19 and 20 to determine bacterial, archaeal, and protozoan diversity using 16S rRNA and 18S rRNA gene amplicon sequencing. UCG-005 genera tended to have a greater relative abundance (RA) in high DFI heifers during P1 (1.50 vs. 0.95, P=0.07). During P2, high DFI heifers had a lower RA of Succiniclasticum (3.88 vs. 4.54, P=0.01) with a tendency for a lower RA of Fibrobacter (4.26 vs. 5.00, P=0.06). High DFI heifers had a tendency for a greater RA of Family_XIII_AD3011_group during P2 (0.91 vs. 0.80, P=0.09) as well as Clostridia_UCG-014 in P2 and P3 (1.13 vs. 0.94, P=0.09; 0.96 vs. 0.45, P=0.45). High DFI heifers also had a tendency for a lower RA of Rikenellaceae_RC9_gut_group (0.18 vs. 0.31, P=0.10) and Coprococcus (0.05 vs. 0.12, P=0.10) during P3 and Mogibacterium during P4 (0.72 vs. 0.92, P=0.09). No differences were observed in Chao1 and Shannon diversity indices of ruminal bacterial communities between heifers DFI groups, however, the Chao1 index of ruminal archaeal communities in high DFI heifers was lower in P1 and P4 (14.86 vs. 16.43, P=0.04; 4.63 vs. 7.43, P=0.03) and showed a tendency to be greater in P2 (18.25 vs. 15.63, P=0.06). High DFI heifers also had a lower RA of Methanobrevibacter during P2 (80.19 vs. 83.75, P=0.04). During P1, amplicon sequencing showed that high DFI heifers had a greater RA of Polyplastron and Entodinium (33.25 vs. 26.31, P=0.02; 25.72 vs. 16.09, P< 0.01) and a lower RA of Diplodinium (0.89 vs. 14.83, P< 0.01). The results of this study indicate notable differences in the rumen microbiota of high and low DFI heifers, which may have contributed to the observed increases in intake, digestibility, and growth.
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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) | 0.001 | 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".