Evaluation of NRC (2000) model energy requirement and DMI equation accuracy and precision for wintering beef cows in western Canada
Bibliographic record
Abstract
Three years of winter feeding trials using 90 Angus cows (15 pens of six cows) fed typical western Canadian wintering diets formulated to stage of pregnancy were used to evaluate National Research Council (NRC 2000) energy requirement and dry matter intake (DMI) equation accuracy and precision. Data collection included pen DMI, individual cow weights, body condition scores, calving dates and weights, and daily environmental temperature. Diet energy density was estimated from nutrient analysis of composited weekly feed samples. Equation evaluations compared observed and predicted DMI and conceptus corrected average daily gain (ADG) for the second and third trimesters using regression, means comparison, concordance correlation coefficient (CCC), and total deviation index (TDI) methods. Across all 3 yr, second trimester DMI was over-predicted (P < 0.01) with low precision (CCC = 0.24, TDI90 = n/a) using actual environmental conditions, but not (P = 0.34) when assuming thermal neutral (TN) conditions, although precision remained low (CCC = 0.25, TDI90 = 1.91 kg d-1). Third trimester DMI over the 3 yr was also over-predicted (P < 0.01) with low precision (CCC = 0.12, TDI90 = 1.57 kg d-1) using actual environmental conditions, but was largely under-predicted (P < 0.01) with lower precision (CCC = -0.01, TDI90 = 2.34 kg d-1) when assuming TN conditions. Across all 3 yr, second trimester ADG was largely under-predicted (P < 0.01) with low precision (CCC = 0.50, TDI90 = 0.58 kg) using actual environmental conditions, but over-predicted (P < 0.01) with similar precision (CCC = 0.51, TDI90 = 0.50 kg) when assuming TN conditions. Third trimester ADG predictions using actual environmental conditions were inaccurate (P < 0.01) with low precision (CCC = 0.20, TDI90 = 0.38 kg) using actual conditions and lower precision (CCC = -0.01, TDI90 = n/a) when assuming TN conditions where ADG was over-predicted (P < 0.01). These results indicate a lack of accuracy and precision with the current NRC (2000) model energy requirement and DMI equations that was not addressed by assuming TN conditions. Future research should be targeted at alternate DMI equations and refinements to maintenance and gain requirements.Key words: NRC evaluation, nutrient requirements, wintering beef cows
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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 | 0.005 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".