Effects of dietary ruminally degradable starch and ruminally degradable protein levels on urea recycling, microbial protein production, nitrogen balance, and duodenal nutrient flow in beef heifers fed low crude protein diets
Bibliographic record
Abstract
Davies, K. L., McKinnon, J. J. and Mutsvangwa, T. 2013. Effects of dietary ruminally degradable starch and ruminally degradable protein levels on urea recycling, microbial protein production, nitrogen balance, and duodenal nutrient flow in beef heifers fed low crude protein diets. Can. J. Anim. Sci. 93: 123–136. The objective was to determine the effects of ruminally degradable starch (RDS; 28.6 and 69.2% of total starch) and ruminally degradable protein [RDP; 48.0 and 55.0% of crude protein (CP)] content on urea recycling, nitrogen (N) balance, duodenal nutrient flow, and microbial protein production in beef heifers fed low CP (10%) diets. Four ruminally and duodenally cannulated beef heifers (723±57 kg body weight) were used in a 4×4 Latin square design with a 2×2 factorial arrangement of dietary treatments with 23-d periods. Jugular infusions of [15N15N]-urea (220 mg d−1; 98+ atom percent) were conducted for 4 d (days 18–22) to estimate urea kinetics, with total collection of faeces and urine. Proportions of [15N15N]- and [14N15N]-urea in urinary urea, and15N enrichment in faeces were used to calculate urea kinetics. Ruminal microbial N production was estimated using15N as a marker. Ruminal ammonia-N concentration was greater (P=0.01) in heifers fed high RDP as compared with those fed low RDP, and it was also greater (P=0.01) in heifers fed low RDS as compared with those fed high RDS. Microbial N flow to the duodenum increased as RDP level increased on the high RDS diet, but was not affected by RDP level on the low RDS diet (interaction; P=0.04). Urea-N entry rate and urea-N transfer to the gastrointestinal tract were similar (P>0.05) across diets. The amount of recycled urea-N incorporated into microbial N increased as RDP level increased on the high RDS diet, but the opposite was observed on the low RDS diet (interaction; P=0.008). These results indicate that at a low CP level (10%), increasing both RDS and RDP levels can increase microbial N flow to the duodenum and improve the efficiency of use of recycled urea-N for microbial N synthesis.
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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) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".