Early Age Thermal Conditioning and a Dual Feeding Program for Male Broilers Challenged by Heat Stress
Bibliographic record
Abstract
The effects of light intensity during sexual maturation on ovarian and carcass morphology at first oviposition [sexual maturity (SM)] were examined in two Single Comb White Leghorn (SCWL) strains. A modern commercial layer strain (COMM; Shaver Starcross 288) and an antique randombred control strain (ANT) were used to compare the effects of changes in laying stock on their response to varying light intensities from photostimulation (PS) until SM. Two hundred pullets from each strain were reared following COMM breeder guidelines. At 18 wk of age, 32 COMM and 32 ANT pullets were individually caged in individually lit cages and photostimulated with light intensities of 1, 5, 50, and 500 lx. Each bird was processed when it reached SM, and carcass and ovarian morphology were assessed. The ANT birds came into production 9.1 d later than the COMM birds, on average. The ANT pullets consumed 7.0% more feed per day than COMM pullets but gained at a slower rate (ANT = 12.9 g/d; COMM = 15.0 g/d). The ANT birds reached SM at a greater weight and with a smaller ovary than did COMM birds. Although the number of large yellow follicles (LYF) was similar between strains (mean = 6.72), both LYF weight and first egg weight were lower in ANT birds than in COMM birds. The COMM layer strain was more growth efficient and had a greater emphasis on ovary maintenance. Light intensity had no effect on the timing of SM or on BW at SM, indicating that all intensities used were effectively able to stimulate the sexual maturation process. However, ovary weight and number of LYF exhibited an increasing dose response to light intensity, particularly in the COMM birds. Overall, the birds photostimulated with 1 lx of light had reduced ovary development and were heavier than their counterparts exposed to 50 and 500 lx. Within the ANT strain, LYF numbers were not significantly affected by light intensities, whereas, within the COMM strain, LYF numbers were 4.88, 6.63, 7.88, and 8.13 for the 1-, 5-, 50-, and 500-lx intensity groups, respectively. Although light intensity did not affect the rate of sexual maturation, it altered ovarian morphology and carcass lipid stores. A light intensity of 1 lx was limiting to ovarian follicle formation and caused increased carcass weight compared with birds on higher light intensity treatments. The COMM birds were more negatively affected by low light intensity than were the ANT birds, indicating that light intensity may be a more critical environmental factor with modern, highly efficient SCWL strains than has previously been thought. Light intensity can affect the reproductive development and likely the associated egg production potential of modern layer stocks.
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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 | 0.001 | 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".