Effects of Light Intensity from Photostimulation in Four Strains of Commercial Egg Layers: 2. Egg Production Parameters
Notice bibliographique
Résumé
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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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».