Evaluation of lighting programs, diet density, and short term use of mash as compared to crumbled starter to reduce incidence of sudden death syndrome in broiler chicks to 35 d of age
Bibliographic record
Abstract
Restricted lighting is used commercially to regulate early growth and limit losses associated with sudden death syndrome (SDS), ascites and leg problems. Standard lighting programs may not be suited for broilers marketed at 35 d of age, and promote injury (scratching, i.e., cellulitis) by creating peak feeding periods. This study evaluates four lighting programs, three phases of mash or crumble starter feeding and two diet densities on performance and mortality of broilers marketed at 35 d of age. Two trials each utilized 7200 male broiler (Cobb × Cobb) chicks randomly housed in six (2.75 × 4.90 m) floor pens in each of eight rearing rooms. Four lighting programs were replicated in each trial and consisted of: (a) 23C (23L:1D 0–35 d); (b) 16C (23L:1D 0–3 d, 16L:8D 4–35 d); (c) DDI (delayed decreasing increasing) (23L:1D 0–3 d; 20L:4D 4–6 d, 16L:8D 7–10 d; 8L:16D 11–15 d; 12L:12D 16–20 d; 16L:8 D 21–28 d; and 20L:4 D 29–35 d); and (d) IL (intermittent lighting, provided in four cycles of 6 h d -1 the same total daily hours of light as the DDI program). Two diet densities were applied for the starter and grower diets; high (ME 3170/3200 kcal; CP 251/210 g) or low (ME 3100/3060 kcal; CP 235/195 g kg -1 starter/grower diet, respectively). The two starter types were fed as combinations of mash (M) or crumble (C): (1) M 0–12 d followed by C 12–21 d; (2) C 0–12 d followed by M 12–21 d; and 3) C 0–21 d. The respective grower/finisher density diets were fed in a pelleted form. By 35 d of age the body weight (BW) of broilers maintained under the DDI lighting program was significantly lower than BW of broilers held under the other lighting programs (16C a > IL ab > 23C b ). Overall (0–35 d) feed conversion (corrected for mortality, but not market weight at 35 d) was highest for broilers reared under the 23C a > IL ab > DDI b > 16C c lighting programs, respectively. SDS (%) mortality was highest for IL (1.68 a ) = 23C (1.53 a ) ≥ 16C (1.02 ab ) ≥ DDI (0.80 b ) lighting programs. There were no significant differences in 35 d BW or feed conversion of broilers fed mash or crumble starter. Feeding mash diets did lower 21 d BW, but this decrease in early growth did not significantly reduce overall mortality. Broilers fed the low as compared to the high density diets weighed less at 21 d, but weighed significantly more at 35 d, and had a higher (P < 0.05) 0–35 d feed conversion. Low as compared to high density diets did reduce SDS mortality significantly (0.72 vs. 1.81%, respectively). Lighting programs that do provide variable extended dark periods will alleviate broiler mortality as compared to constant (23 or 16 h) or intermittent lighting programs. However, these broilers had a significantly lower body weight when marketed at 35 or less days of age. Key words: Lighting, broilers, mash, diet density, sudden death, ascites
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".