Relevance of Nitrogen Correction for Assessment of Metabolizable Energy with Broilers to Forty-Nine Days of Age
Bibliographic record
Abstract
An experiment was conducted to reevaluate the concept of using AME vs. AME(n) values for broiler diets. Growing male broilers and adult Leghorn roosters were fed either a single standard diet from 0 to 49 d or a series of starter (0 to 21 d), grower (21 to 35 d), and finisher (35 to 49 d) diets. Apparent ME and AME(n) were determined during 4 to 7, 11 to 14, 18 to 21, 25 to 28, 32 to 35, 39 to 42, and 46 to 49 d of age. Using the single diet after 7 d, the broiler consistently derives higher AME than do roosters. This same effect was seen with the multiple diet series for broilers. However when N correction is applied, the converse situation is seen, in that roosters consistently attain higher AME(n) than do broilers at any given age. Using a single diet, rooster AME and AME(n) values were unaffected by time, whereas broilers exhibit a quadratic relationship for both AME and AME(n) through 49 d. Nitrogen retention of roosters was rarely different from zero (P > 0.05). For broilers, there was a significant (P < 0.01) increase in grams of N retained each day over time, although when expressed as a percentage of N intake, there was decline over time, especially after 28 d of age. The N correction imposes a 4 to 5% reduction on the AME value of a single diet. When a commercial series of diets was used, the correction declined from 5.3% at 7 d to 3.8% at 49 d, reflecting the decline in protein content of the diet and the decline in N retention over time. This information suggests that if AME rather than AME(n) values are accepted, then roosters provide a good estimate of values applicable for broiler nutrition, because values are little different. Because there was less variance in energy values expressed as AME(n) rather than AME, it appears that there was sufficient bird-to-bird variation in growth, N retention, or both, to warrant the use of the correction factor.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| 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".