Effects of Light Intensity from Photostimulation in Four Strains of Commercial Egg Layers: 2. Egg Production Parameters
Bibliographic record
Abstract
The effects of light intensity (LI) from photostimulation to 45 wk of age on egg production parameters and egg size characteristics were examined in four layer strains. Floor housed pullets were raised in a light-tight facility from 1 d of age until housing in individually illuminated cages at 17 wk of age. At 17 wk of age, two white egg strains, ISA-White (ISA-W) and Shaver 2000 (S2000), and two brown egg strains, ISA-Brown (ISA-B) and Shaver 579 (S579), were assigned to a processing group [Group 1 was killed at sexual maturity (first oviposition); Group 2 was kept to 45 wk] and were photostimulated at 18 wk of age using a LI of 1, 5, 50, or 500 lx (4 x 4 factorial design). One bird from Group 1 and one bird Group 2 were caged together in individually lit cages (one brown and one white egg layer). Cages were equipped with hardware to monitor egg laying time. Data of individual egg weight and time of lay were kept on Group 2 birds until 45 wk of age. Egg production data were analyzed for hen-day production, laying sequence length, egg and egg component weights, time of lay, and egg interval time as related to strain or LI. Hen-day production was greater in brown egg strains (ISA-B = 86.7%, S579 = 88.1%) than in white egg strains (ISA-W = 83.4%, S2000 = 82.3%) and was reduced in birds under 1 lx compared to 5 or 50 lx. A LI of 1 lx resulted in reduced egg production and laying sequence length compared to birds with a 50 or 500 lx. The effects of LI were strain dependant, however. Postpeak sequence length and egg production declined at more rapidly under 500 lx compared to other LI in brown egg strains, indicating possible development of a photorefractory condition. Mean settable egg weight was lower in 500 lx birds (56.1 g) compared to other groups (mean = 57.9 g), reducing total egg mass produced. Mean interval between successive eggs in a sequence was lengthened in 1 lx birds compared to other LI groups. Mean time of lay was earlier in brown egg strains than in white egg strains by 48 min. Mean time of lay was shifted to occur later by an increasing LI. Light intensity affected sexual maturation and egg production, as layers had differential responses to lighting. LI of 1 lx and 500 lx were found to be limiting to the egg production efficiency of layers. Whereas the birds receiving 1 lx had a reduced rate of egg production, those receiving 500 lx had reduced egg size later in the production period in combination with reduced shell quality, which indicated that inadequate feed intake under high LI conditions may be a factor affecting layer stocks. Exposure to high LI reduced egg size and total egg mass produced. Ultimately, the brown egg strains appeared to be more susceptible to the negative effects of low or high LI, indicating the importance of matching management practices to the particular hen genotype.
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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 | 0.000 | 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".