1313 Effect of potassium carbonate and soybean oil supplementation on rumen microbial population linked to lipid metabolism
Bibliographic record
Abstract
The rumen microbial ecosystem plays a crucial role in productivity through digestion of feeds and supply of nutrients to the host animal. It was suggested that milk fat synthesis in dairy cows is stimulated by a positive dietary cation-anion difference (DCAD). Despite that rumen bacteria are largely involved in hydrolysis and biohydrogenation of dietary lipids, the impact of DCAD on rumen microbiome is unknown. The objective of this study was to evaluate the effect of increasing DCAD, using K2CO3, in diets containing soybean oil (SBO) on rumen microbial population associated with lipid metabolism. Twenty four early lactation Holstein dairy cows (39 ± 22 DIM) were used in a randomized complete block design (6 blocks) based on DIM and number of calving with a 2 × 2 factorial arrangement of treatments. Within each block, cows were fed a basal diet formulated to achieve 40% forage (58% corn silage), 60% concentrate, and 47% non-fibrous carbohydrates, with 0 (DCAD: +95 mEq/kg) or 1.5% K2CO3 (DM basis; DCAD: +316 mEq/kg), and 0 or 2% SBO. Effects of K2CO3, SBO and the interaction K2CO3 × SBO were evaluated. Treatment period lasted 28 d; the last 5 d were used for data and sample collection. Equal volumes (?1.0 L) of rumen fluid and solid digesta were collected from different rumen sites 4-h postfeeding. Extracted DNA was amplified by quantitative real-time PCR. The absolute amount for each microbial group was expressed as logarithm (base 10) of DNA copies/g of fresh matter. A companion abstract showed an interaction between K2CO3 and SBO on milk fat yield and t10/t11 ratio (JDS 98-Suppl. 2:128). Supplementing diets with K2CO3 stimulated the growth of Butyrivibrio hungatei (5.79 vs. 5.62; P = 0.03), a bacteria recognized to produce t11 18:1 during biohydrogenation. Conversely, feeding SBO reduced the growth of i) Butyrivibrio/Pseudobutyrivibrio group (8.60 vs. 8.80; P = 0.04), also known to produce t11 18:1, ii) fibrolytic Fibrobacter succinogenes (9.34 vs. 9.63; P = 0.04), iii) Butyrivibrio proteoclasticus, a bacteria involved in 18:0 production (6.67 vs. 6.79; P = 0.06), and iv) amylolytic Streptococcus bovis (6.84 vs. 7.01; P = 0.06). Feeding K2CO3 had no effect on these four bacteria. Total eubacteria and total protozoa did not differ between treatments (P > 0.13). Feeding K2CO3 and SBO had distinct effects on rumen bacteria. However, the absence of interaction between treatments on microbial population does not allow to establish a clear link with previously observed effects on milk fat yield and t10/t11 ratio.
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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".