Effect of partial exchange of lactose with fat in milk replacer on ad libitum feed intake and performance in dairy calves
Notice bibliographique
Résumé
Compared with Holstein whole milk, commercial milk replacers (MR) for calves deliver relatively high levels of lactose and low levels of fat, and protein levels are rather comparable, resulting in a lower energy density and energy-to-protein ratio of the diet. Thus, the objective of this study was to determine the effects of partially exchanging lactose with fat in MR on voluntary feed intake, growth performance, and feeding behavior. Thirty-two male Holstein calves (2.1 ± 0.16 d of age, 46.4 ± 0.77 kg of body weight; BW) were assigned to 16 blocks of 2 calves per block based on arrival date and serum IgG. Within each block, calves were randomly assigned to 2 treatments: a high-lactose MR (HL; 17% fat; 44% lactose), or a high-fat MR (HF; 23% fat; 37% lactose). Lactose was exchanged by fat on a weight per weight basis, resulting in a 6% difference in metabolizable energy density per kilogram of MR. The experiment was divided into 3 phases: preweaning (P1; 0-35 d), weaning (P2; 36-56 d), and postweaning (P3; 57-84 d). For the first 2 wk of P1, calves were individually housed, fed their respective MR ad libitum through teat buckets, and provided access to water. At 14.2 ± 0.5 d of age, calves were group-housed (4 blocks/pen, 8 calves) and housed in group pens for the remainder of the study. In the group pens, calves were fed ad libitum MR, starter feed, chopped wheat straw, and water via automated feeders. During P2, calves were gradually weaned until complete milk withdrawal by 57 d and then monitored until 84 d (P3). Measurements included daily intakes and feeding behavior (rewarded and unrewarded visits), weekly BW and body measurements, and biweekly blood samples. Increasing fat content at the expense of lactose decreased MR intake during P1 by 15% (HL = 1.32 ± 0.04; HF = 1.17 ± 0.04 kg of dry matter per day), whereas total starter intake was not affected by MR composition. Once MR was restricted during P2, HL calves were reported to have more unrewarded visits to the automatic milk feeder than HF calves (11.9 ± 0.95 vs. 8.4 ± 1.03 visits/d, respectively). Crude protein intake was higher for HL calves during P1 (352.1 ± 11.2 vs. 319.6 ± 11.6 g/d), which was attributed to the higher intake of MR during that period, and metabolizable energy intake and protein-to-energy ratio remained comparable between treatments. Plasma cholesterol and nonesterified fatty acids levels were higher in HF calves as a consequence of the diet. Nevertheless, final BW (84 d) did not differ between treatments. Overall, calves fed ad libitum seemed to regulate their intake of MR based on its energy density, without significant effects on solid feed intake and overall growth.
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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 | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 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 | 0,001 |
| 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 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 ».