The genetic basis and improvement of feed efficiency in lactating Holstein dairy cattle
Notice bibliographique
Résumé
Improvement of feed utilization of the dairy cow through genetic selection may be a solution to increasing the environmental and economic sustainability of the dairy industry. Understanding the genetic basis of feed efficiency is imperative such that selection strategies can be optimized. The objective of this dissertation was to characterize the genetic architecture of feed efficiency, explore strategies for predicting genetic merit for feed efficiency, and consider the impact that selection for feed efficiency could have on related traits. Feed efficiency-related phenotypes and genotypes were collected on 4,916 cows from the United States, Canada, the Netherlands, and the United Kingdom. Residual feed intake (RFI) was chosen as the measure of feed efficiency. A genome-wide association study was performed separately for primiparous and multiparous cows, and genetic correlations were estimated with phenotypes in the two parity groups considered as separate traits. Results from these analyses suggested that RFI is a highly polygenic trait and has a genetic basis that is distinct from production traits and differs between primiparous and multiparous cows. Beta-3 adrenergic receptor (ADRB3) and leptin (LEP) were identified as candidate genes for RFI in primiparous and multiparous cows, respectively. Because many loci explained genetic variation of RFI, genomic prediction strategies were explored such that genetic markers across the genome could be utilized to estimate breeding values for animals. Results indicated that the accuracy of prediction was lower for RFI than related traits that in combination could be explored as predictors of feed efficiency. On a subset of cows, surface body temperature as measured by thermal imaging was explored as an indicator trait and considered as an alternative strategy for use in the estimation of genetic merit. A positive relationship between rear leg temperature and RFI was established, and surface temperature was moderately heritable, but the percentage of variation in RFI explained by surface temperature and the confidence in genetic correlation between RFI and surface body temperature were weak. In a final study, the possibility that improved feed efficiency may inadvertently favor cows that mobilize body tissue in early lactation was explored. Feed efficient cows when defined as RFI carried more body condition throughout lactation and body condition loss was not different between feed efficient and inefficient cows. In conclusion, implementation of selection strategies in conjunction with the consideration of adverse effects may be valuable to improve the feed efficiency of dairy cows.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,000 |
| 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 ».