243 The effect of binding feed enzymes to spores of Bacillus subtilis (var. natto) on in vivo digestibility and in situ disappearance
Bibliographic record
Abstract
The objective of this study was to determine whether binding a commercial xylanase feed enzyme to the surface of Bacillus subtilis spores would improve feed digestibility compared to free enzyme. An in vivo study was conducted using 4 treatments: control (CON; no enzyme), B. subtilis spores (SPR; 1.0 × 1010 spores/kg DMI), free enzyme (ENZY; 2.5 ml of commercial xylanase enzyme/kg DMI), and spore-bound enzyme (SBE; 2.5 ml of commercial xylanase enzyme bound to 1.0 × 1010 spores/kg DMI) applied to alfalfa grass hay. The treatments were fed to 4 ruminally and duodenally cannulated heifers in a 4 × 4 Latin square design, with 21 d experimental periods and a 7 d washout between periods. Ruminal in situ disappearance was determined on d 13 to 18, where triplicate polyester bags containing alfalfa grass hay (5 g) were removed after 0, 4, 8, 12, 24, 36, 48, 72, 96, and 120 h of incubation. Total collection of feces and feed refusals occurred on d 19 to 21 to measure total tract digestibility. Rumen and fecal samples were collected and processed for 16S rRNA gene sequencing to analyze bacterial microbiota. There were no differences in ruminal in situ rates of disappearance of DM, OM, NDF, or ADF (P ≥ 0.086). Effective rumen degradability of DM and OM was greater for ENZY, SBE, and SPR compared to CON (P ≤ 0.048), but there was no difference between ENZY and SBE (contrast P ≥ 0.146). Total tract and ruminal DM and OM digestibilities were not affected by treatment (P ≥ 0.067); however, intestinal DM and OM digestibilities were increased for SBE (SBE vs ALL, P ≤ 0.043). There was also an increase in total tract digestibility of NDF and ADF for SBE (SBE vs ALL, P ≤ 0.048). Rumen microbiota diversity was affected by treatment, with differences observed between CON and SPR (P = 0.050), CON and SBE (P = 0.033), and SPR and SBE (P = 0.009). There was no difference in fecal microbiota diversity between CON and SPR (P = 0.113) or SPR and SBE (P = 0.406), but fecal microbiota was different between CON and SBE (P = 0.009) as well as ENZY and SBE (P < 0.001). These results suggest that spore-bound enzymes are more stable than free enzyme, increasing total tract digestibility of NDF and ADF. The effects likely resulted from enhanced postruminal digestion and alteration of the gastrointestinal microbiota.
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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 | 0.001 |
| 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".