Effect of amino acid or casein supply on whole-body, splanchnic, and mammary glucose kinetics in lactating dairy cows
Notice bibliographique
Résumé
This study was conducted to establish how AA supplied in a free form or as protein (casein, CN) affect the whole-body rate of appearance (WB Ra) of glucose, splanchnic and mammary glucose kinetics, and milk lactose secretion in lactating dairy cows. Five Holstein cows fitted with a rumen cannula and permanent indwelling catheters in the abomasum, portal, hepatic, and mesenteric veins, and one mesenteric artery, were used in a Youden square with 4 periods of 14 d each. Cows were fed a hay-based diet providing 100 and 70% of their net energy and metabolizable protein (MP) requirements, respectively. Treatments consisted of abomasal infusions of water (70% of MP requirements: control, Con), free AA (95% of MP requirements: AA1; and 120% of MP requirements: AA2), or CN (95% of MP requirements: CN1). The free AA mixture had the same profile as CN. On d 14 of each period, [6,6-(2)H(2)]glucose (25.8 mmol/h) was infused into a jugular vein, and blood samples (n=8) were taken over 4h from arterial, portal, hepatic, and mammary sources to measure glucose enrichment and concentration. Splanchnic and mammary plasma flows were determined by downstream dilution of para-aminohippurate and with the Fick principle, respectively. The last 6 milkings of each period were weighed and sampled to measure the yields of milk and components. The AA1 and CN1 treatments were not different for any of the measured parameters. Supplying AA linearly increased glucose WB Ra (AA2 vs. Con: +151 mmol/h) and liver net flux (+149 mmol/h). Utilization of glucose from the plasma compartment by the portal-drained viscera and liver and true portal absorption were not affected by AA supply. From these observations, we suggest that the increased WB Ra was due to increased net hepatic production. The AA from the infusion, in excess of that used to cover the increase in milk protein, were converted to glucose with an apparent efficiency close to 100% of maximum theoretical efficiency. Milk and lactose yields increased linearly with infusions of AA, by 14 and 16% with AA2 treatment, respectively. However, mammary glucose uptake was not significantly altered by AA infusions; this suggests that the mammary gland exerts active control on the uptake and utilization of glucose. For all treatments, the sum of true portal glucose absorption and true hepatic glucose production contributed more than 99% of WB Ra in the lactating cow; this would suggest that renal glucose synthesis makes only a small contribution to WB Ra under these conditions.
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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 | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 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 ».