Effects of increasing dietary levels of a palmitic acid–enriched supplement on fiber digestibility, rumen fermentation, and microbial composition in high-fiber diets
Bibliographic record
Abstract
Recent research has highlighted that palmitic acid (PA)-enriched supplements increase NDF digestibility, likely due to rumen microbial composition and changes in metabolism. However, the effect of different PA doses on fiber digestibility and rumen metabolism remains unclear. Thus, this study aimed to investigate the effects of increasing dietary levels of a PA-enriched supplement on fiber digestibility, rumen fermentation, and microbial composition using continuous culture fermenters. Diets were assigned to 8 dual-flow continuous culture fermenters arranged in a replicated 4 × 4 Latin square with four 11-d experimental periods. The treatments included a basal control diet (50:50 forage:concentrate) without a PA-enriched supplement and the basal diet supplemented with incremental levels of supplemental PA at 0.85%, 1.70%, or 2.25% of DM. The supplement contained 85.0% C16:0, 3.10% C18:0, 9.70% cis-9 C18:1, and 97.4% total fatty acids. Buffer dilution and solids passage rate were maintained at 7.0%/h and 5.0%/h, respectively. Samples were collected in the last 4 d of each period. Data were analyzed using a mixed model considering treatments as fixed effects and period and fermenter as random effects. Digestibility of NDF responded quadratically to PA inclusion, with 0.85% PA resulting in the highest digestibility, followed by 1.70% PA and 2.55% PA, and ADF digestibility showed a similar quadratic trend as the PA dose increased. No treatment effects were observed for OM, starch, or hemicellulose digestibility. Propionate flow also tended to respond quadratically, peaking at 0.85% PA, whereas isobutyrate and valerate flow increased linearly with PA inclusion. Microbial growth per kilogram of degraded ADF and NDF showed a quadratic response increasing at 2.55% PA, indicating improved microbial efficiency. Although we did not observe treatment effects on the α- and β-diversity of the microbial population, the relative abundances of several bacterial phyla, families, and genera responded quadratically to PA, increasing Prevotellaceae and decreasing Lachnospiraceae relative abundance. These findings underscore the potential of PA to enhance fiber digestibility through shifts in bacterial metabolism and the abundance of fiber-degrading bacteria. However, further research is necessary to understand broader implications for microbial energy use, growth, and efficiency.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".