A randomized controlled trial investigating the effect of transport duration and age at transport on surplus dairy calves: Part I. Impact on health and growth
Notice bibliographique
Résumé
Calves arriving to veal and dairy-beef facilities in poor condition are at risk of future health challenges and reduced growth rates, and limited knowledge is available on how time in transit affects subsequent health and growth of these animals. The objective of this randomized controlled trial was to understand the effects of transport duration on diarrhea, respiratory disease, and growth of surplus calves destined for veal production following 6, 12, or 16 h of continuous road transport. Surplus dairy calves (n = 175; 7 transport cohorts) from 5 commercial dairy farms in Ontario, Canada, were enrolled on the day of birth. These calves were clinically examined daily on the source farms until the day before transport and on a daily basis for the first 14 d at the veal farm. On the day of transport, they were randomly assigned to 6, 12, or 16 h of transport to a veal farm. A blood sample was collected between 24 and 48 h of birth to assess transfer of passive immunity status. Calves were weighed at birth, before and immediately after transport, as well as 24, 48, and 72 h after unloading. Calves were also weighed 14 and 50 d after transport. Health exams were conducted daily at the source farm, immediately before and after transport, and once daily for 14 d thereafter to evaluate clinical signs of diarrhea, respiratory disease, dehydration, and navel inflammation. Mixed effects Poisson regression models were used to evaluate variables associated with the number of days with abnormal respiratory and fecal scores, whereas mixed logistic regression models with repeated measures were built to assess the probability of a calf having abnormal respiratory scores, abnormal fecal scores, or dehydration by day after arrival to the facility. A mixed model with repeated measures was used to evaluate calf weight at each time point at which body weight was measured after transport, whereas a mixed linear regression model was used to evaluate factors associated with average daily gain (ADG) in the 50 d after transport. Calves transported for 16 h had greater incidence of abnormal fecal scores compared with 6 h in the 14 d after transport. In addition, an interaction between age and duration of transport on the number of days with abnormal respiratory scores was identified, where calves older than 7 d of age had reduced incidence of abnormal respiratory score compared with calves 2 to 6 d old, even when transported for 16 h. As for growth, age at transport was positively associated with ADG in the 50 d of observation; however, no differences were observed between transport duration groups. These findings highlight that transporting calves for a longer duration negatively affects subsequent health, and calves greater than 1 wk of age experience improved health and growth after transport compared with their younger counterparts.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,003 | 0,006 |
| Méta-épidémiologie (sens strict) | 0,002 | 0,001 |
| Méta-épidémiologie (sens large) | 0,004 | 0,002 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,002 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,004 | 0,003 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,009 | 0,001 |
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 source (Gemma direct ou Codex distillé), 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 ».