Potassium carbonate as a cation source for early-lactation dairy cows fed high-concentrate diets
Bibliographic record
Abstract
Previous studies reported that addition of K 2 CO 3 to high-concentrate diets improved milk fat synthesis, although the mechanism is yet to be established. The objective of the current experiment was to investigate the effects of dietary cation-anion difference (DCAD), cation source, and buffering ability of the mineral supplement on rumen biohydrogenation of fatty acids and production performance in dairy cows fed a high-concentrate diet. Thirty-five early-lactation Holstein cows (25 multiparous ruminally fistulated and 10 primiparous nonfistulated) were used in a randomized complete block design (7 blocks) with 33-d periods, including a 5-d pre-treatment collection period used as a covariate. Diets were (1) control, a basal diet [47% nonfibrous carbohydrates, DCAD (Na + K – Cl – S) = 65 mEq/kg of dry matter (DM)] containing 40% forage (including 60% corn silage) and 60% concentrate, (2) K 2 CO 3 (control + K 2 CO 3 , 1.8% of DM, DCAD=326 mEq/kg of DM), (3) KHCO 3 (control + KHCO 3 , 2.6% of DM, DCAD=324 mEq/kg of DM), (4) KCl (control + KCl, 2.0% of DM, DCAD=64 mEq/kg of DM), and (5) Na 2 CO 3 (control + Na 2 CO 3 , 1.4% of DM, DCAD=322 mEq/kg of DM). Pre-planned orthogonal contrasts were used to assess the effects of K 2 CO 3 (control vs. K 2 CO 3 ), buffering ability (K 2 CO 3 vs. KHCO 3 ), DCAD (K 2 CO 3 vs. KCl), and cation type (K 2 CO 3 vs. Na 2 CO 3 ). Supplementing K 2 CO 3 in a high-concentrate diet did not improve milk fat yield or 4% fat-corrected milk yield. Milk fat concentration was greater in cows fed K 2 CO 3 compared with control (4.03 vs. 3.26%). Milk yield tended to decrease (34.5 vs. 38.8 kg/d) and lactose yield decreased in cows fed K 2 CO 3 as compared with KCl (1.64 vs. 1.87 kg/d). Milk fat concentration of trans -10 18:1 was increased when cows were fed Na 2 CO 3 as compared with K 2 CO 3 . A positive relationship was observed between concentrations of anteiso 15:0 and trans -10, cis -12 18:2 in milk fat from cows receiving K 2 CO 3 . Milk Na concentration was increased, whereas milk Cl was decreased with K 2 CO 3 as compared with KHCO 3 or KCl. A positive relationship was established between milk Cl concentration and milk yield (R 2 = 0.34) across all dietary treatments. Cation-anion difference (Na + K – Cl – S) in ruminal fluid was increased with K 2 CO 3 as compared with control or KCl. Blood pH tended to decrease in cows fed KCl compared with K 2 CO 3 . Our results suggest that mineral supplementation tends to affect milk and milk fat synthesis and that factors other than DCAD, potassium ion, or buffer ability may be implicated. The variations observed in mineral composition of milk suggest an allostatic process to maintain an ionic equilibrium in mammary epithelial cells in response to mineral composition of the diet.
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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".