Effects of supplementing a Bacillus-based direct-fed microbial on ex vivo fermentation traits and on performance of lactating Holstein dairy cows
Bibliographic record
Abstract
Three studies evaluated the effects of a Bacillus -based direct-fed microbial (DFM) on ex vivo fermentation traits, as well as on performance of lactating dairy cows. In experiment 1, rumen-fistulated lactating Holstein-Friesian cows (6.6 ± 2.3 parity; 630 ± 37.2 kg BW; 18.9 ± 3.35 kg milk/d) were fed an unsupplemented ration (CON; n=5) or supplemented with 3 g/cow per d of a Bacillus -based DFM (BAC; n=5) for 14 d before rumen sampling and subsequent ex vivo evaluation of fermentation characteristics of 2 different substrates (vetch hay [ Vicia sativa ] and perennial ryegrass herbage [ Lolium perenne L.]). Total gas production, methane (CH 4 ), VFA, and rumen ammonia-N were determined after 24 h of fermentation. In experiment 2, 60 Holstein cows (mean ± SD; 61 ± 3 DIM) fed a 39:61 forage-to-concentrate TMR were assigned to CON or BAC (3 g/cow daily for 13 wk; n=30 cows per group). In experiment 3, 76 Holstein cows (25 ± 3 DIM) fed a 55:45 forage-to-concentrate TMR were assigned to CON or BAC (3 g/cow daily for 12 wk; n=38 cows per group). Dry matter intake, milk yield, milk composition, and feed efficiency were evaluated for both experiments 2 and 3. Data from all experiments were analyzed using mixed-effects models. In experiment 1, ruminal concentrations of total VFA, as well as molar proportions of butyrate, isovalerate, valerate, acetate-to-propionate ratio, and NH 3 -N increased in BAC compared with CON. In contrast, molar proportions of acetate and propionate were lower for BAC than for CON. Gas production was increased in BAC when adjusted for the amount of DM incubated without affecting CH 4 production. In experiment 2, DMI decreased for both groups starting at wk 7 of the study, but BAC cows consumed less feed than CON cows from wk 8 to 11 and at wk 13. As a consequence, feed efficiency was greater for BAC than for CON cows from wk 5 to 11 and at wk 13 of the study. In experiment 3, mean DMI, milk yield, ECM yield, and milk TS yield were greater in BAC than in CON cows. Altogether, these results indicate that feeding a Bacillus -based DFM is a feasible alternative to promote dairy cow productivity, likely through beneficial changes in ruminal fermentation.
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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) | 0.001 | 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".