Impact of growth trajectory on sexual maturation in layer chickens
Bibliographic record
Abstract
Recent studies showed that apart from photostimulation, metabolic triggers may independently activate sexual maturation and egg production in chickens. However, the origin, mode of action, and specific target(s) of this metabolic control remain unknown. Beyond body weight (BW), we hypothesize that body composition (BC) and associated specific metabolic signals are involved. Thus, this study was conducted to determine the BW and BC thresholds triggering spontaneous sexual maturation in layer pullets under different growth trajectories. Day-old Lohman LSL lite and Lohman brown lite chicks ( n = 210 each) raised in brooding cages under ad libitum (AL) feeding until 8 weeks of age were randomly allocated into individual cages and assigned to one of 3 experimental growth profiles; AL, breeder’s target (T), restricted 20% below target (R), ( n = 70 birds/profile/strain). Birds had free access to water throughout the trial. All hens were maintained on 10 h of light (10 lux) throughout the rest of the study. Blood and tissue samples were collected throughout the study to measure plasma estradiol (E 2 ) concentrations and organ weights, respectively. Furthermore, carcasses were subjected to Dual-energy X-ray absorptiometry (DEXA) analyses. All analyses were completed with SAS using the MIXED procedure. Results show that R treatment slowed ( p < 0.001) growth, delayed age at first egg (FE) and egg production ( p < 0.001) and resulted in lower BW at FE ( p < 0.001), lower ovary weight and number of follicles ( p < 0.001) compared to AL in both strains, whereas, the strain significantly impacted body weight ( p < 0.0001), ovary weight ( p < 0.001), BW at FE ( p < 0.001), age at FE ( p < 0.001), egg production ( p < 0.0001), E 2 ( p < 0.0001) and body composition ( p < 0.05). For DEXA, AL feeding ( p < 0.001) increased fat deposition compared to R. Furthermore, there was a positive correlation between plasma E 2 and bone mineral content ( p < 0.01) and bone mineral density ( p < 0.01). In conclusion, feed allocation impacted growth and BC in a strain dependent manner which resulted in differing age at sexual maturation and egg production. Furthermore, a body fat threshold between 10% to 15% appears to be required for the occurrence of spontaneously sexual maturation in laying hens.
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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".