The effects of viral vaccination of dairy heifer calves on the incidence of respiratory disease, mortality, and growth
Notice bibliographique
Résumé
Bovine respiratory disease (BRD) is one of the most common infectious causes of morbidity and mortality in young dairy cattle. The objective of this randomized clinical trial was to determine the effectiveness of 1 or 2 doses of a 5-way, modified-live viral vaccine, administered to heifer calves before weaning to aid in the prevention of BRD. The hypotheses were that vaccination would reduce the incidence of BRD and mortality, and that 2 doses would be more effective than 1. A total of 2,874 heifer calves from 19 commercial dairy farms in Minnesota and Ontario were enrolled at 1 to 7d of age and were followed until 3 mo of age. Calves were randomly assigned to receive a commercial, intramuscular, modified-live vaccine against bovine viral diarrhea virus types 1 and 2, bovine respiratory syncytial virus, bovine herpesvirus type 1, and parainfluenza virus type 3 at 15 to 21 d of age (2 wk only), 35 to 42 d (5 wk only), both 2 and 5 wk, or sterile saline at both times (unvaccinated controls). The incidence of failure of passive transfer was 11 or 32%, using cut-points of serum total protein of 5.2 and 5.7 g/dL, respectively. Overall, 22% of calves were treated at least once for BRD. The incidence risk of naturally occurring BRD was 7.7% before 2 wk of age, 8.0% between 2 and 5 wk, and 9.5% between 5 wk and 3 mo of age, and was not different between vaccination groups. Overall mortality throughout the 3-mo study period was 3.5%. Mortality was 1.6% before 2 wk of age, 0.5% between 2 and 5 wk, and 1.2% between 5 wk and 3 mo of age. The risk of mortality was not affected by vaccination. Mean average daily gain of 1.07 kg/d from 5 wk to 3 mo of age was not different between vaccine groups. In this population of commercial, home-raised calves, with an overall low incidence of failure of passive transfer, intramuscular vaccination with a multivalent, modified live viral vaccine at 2 or 5 wk of age or both was not associated with a decreased risk of BRD or mortality, or with growth until 3 mo of age. Reasons for these findings may include interference by maternal antibodies, unresponsiveness of the neonatal immune system, timing of immunity relative to pathogen exposure, disease caused by pathogens other than the viruses in the vaccine, or herd immunity. However, in populations with higher incidence of failure of passive transfer or risk of BRD, calves with low levels of specific antibodies may respond differently to vaccination.
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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 | 0,002 | 0,002 |
| 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 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| 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 ».