Effects of Light Intensity from Photostimulation in Four Strains of Commercial Egg Layers: 1. Ovarian Morphology and Carcass Parameters
Bibliographic record
Abstract
We examined the effects of light intensity (LI) from photostimulation to 45 wk of age on egg production parameters and egg size characteristics and on ovarian and carcass morphology at sexual maturity and 45 wk of age 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. 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 used. Pullets were randomly assigned to a processing group that was killed at sexual maturity (first oviposition) (Group 1) or kept to 45 wk (Group 2). Birds 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 from Group 2 were caged together in individually lit cages (one brown and one white egg layer). Carcass and ovarian morphology data were examined as related to Strain, LI, or the interaction of Strain and LI. The time from photostimulation to sexual maturity did not differ due to LI, but was shorter for brown egg strains (ISA-B = 19.9 d, S579 = 20.2 d) than for white egg strains (ISA-W = 26.6 d, S2000 = 28.1 d). Body weight at sexual maturity differed among all strains, with the white egg strains having the lowest BW. Ovary weight was the greatest in ISA-W birds, in which 8.0 large yellow follicles (LYF) were present compared to 6.8 in S2000 birds. The LI affected ovary development, as birds with the 1 lx exposure had lower ovary weights and fewer LYF than did 50 lx birds, suggesting that the 1 lx LI did not result in an adequate photostimulatory cueing of sexual maturation. The threshold LI for a complete morphological response to photostimulation in this study was 5 lx. Strain differences in BW observed at sexual maturity continued to 45 wk of age. Light intensity affected 45 wk BW, with 5 lx LI birds weighing 7.2 and 8.7% more than the 50 and 500 lx birds, respectively. On an absolute basis, brown egg stains carried significantly more breast muscle at 45 wk of age than did white egg strains. The fatpad was heavier on a relative basis for brown egg layers than white egg layers. The 1 lx hens had lower 45-wk ovary weights than did the other three LI treatments. These data support the conclusion that with the development of highly specific genetic strains, it is increasingly important to match the environmental management practices to a particular hen's 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 | 0.000 |
| 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".