Impact of passive immunity and quality of transition milk on preweaning dairy and dairy-beef cross calf health in a pasture-based block calving system: A cohort study
Notice bibliographique
Résumé
The objective of this observational cohort study was to evaluate how passive immunity, measured by serum IgG at 24 to 36 h of life, and transition milk quality (assessed via IgG intake) was associated with mortality, treatment incidence, antimicrobial use and growth in dairy calves reared within a pasture-based block calving system. This study was conducted between February and June 2024 on a 550-cow spring calving herd in Pembrokeshire, West Wales, United Kingdom. A total of 251 calves were included in the study which comprised 139 British Friesian dairy replacements, and 92 Wagyu, 19 Hereford, and 1 Simmental beef-on-dairy calf. Calves were left with their dam immediately after birth, which allowed them to potentially suckle maternal colostrum, before being separated and fed colostrum replacer. Excess colostrum from the dam (from the first milking after calving, after the calf had suckled) and subsequent transition milk from milkings 2 to 6 after calving was pooled, pasteurized, and fed to all calves from the second feeding up to 10 d of age. Every calf was blood sampled to assess the concentration of serum IgG at 24 to 36 h of age using radial immunodiffusion (RID) testing. The transition milk mixture was collected daily and tested using RID to determine the total quantity of IgG fed over the 10-d period to each calf. The incidence of mortality and morbidity was recorded using DairyComp305 (version, 23.11, release date Nov. 28, 2023;Valley Ag Software, VAS), whereas live weight gain was recorded using a weigh tape at birth and digital scales at weaning. The mortality rate from enrollment to weaning was 12.4%, with several associations identified, including the level of passive immunity, month of calving, and an interaction between the level of passive immunity and quantity of IgG fed through transition milk. Specifically, calves born in April and May had higher odds of dying in the preweaning period compared with calves born in February. In addition, for every 1 g/L increase in serum IgG measured at 24 to 36 h of age, the odds of mortality declined. Finally, lower mortality was observed in calves with lower serum IgG at 24 to 36 h when receiving higher IgG in transition milk. A total of 42 calves (16.7%) were treated during the preweaning period. A higher concentration of serum IgG at 24 to 36 h was also linked to lower treatment rates, as was month of birth, with those born in March and April having higher odds of treatment. The median defined daily dose for animals (DDDvet) was 0, with a range of 1 to 16.66. Similar to previous findings, serum IgG was associated with this outcome, where calves with serum >22.18 g/L having a lower DDDvet compared with those with a serum IgG of <9.30 g/L. Over the preweaning period, the average growth rate was 0.39 kg/d. Calves with serum IgG concentrations >22.18 g/L gained 0.08 kg/d more compared with those with a serum IgG of <9.30 g/L. Further, calves fed >470 g of IgG in transition milk gained 0.07 kg/d more than those that consumed <260 g of IgG in transition milk. However, no differences in ADG were found for calves consuming 260 to 325 g or 326 to 465 g compared with those in the <260 g group. This study demonstrated that higher levels of passive immunity were associated with reduced mortality, lower odds of disease treatment and antibiotic use, and improved growth rates, whereas increased IgG intake through transition milk was associated with reduced preweaning mortality, especially in calves with low passive immunity, and improved growth, underscoring the importance of passive immunity and transition milk feeding in pasture-based block calving systems.
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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 | 0,001 | 0,001 |
| 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 | 0,001 | 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) | 0,001 | 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 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 ».