Metabolic responses, performance, mammary gland development and gene expression in liver and muscle of Holstein × Gyr crossbred heifers grazing intensively-managed brachiaria decumbens supplemented with varied crude protein and association of housing and management practices with milk yield, milk composition, and fatty acid profile, predicted using fourier-transform mid-infrared spectroscopy, in farms with automated milking systems
Notice bibliographique
Résumé
The objectives of the first and second study were to evaluate the effect of crude protein (CP) supplementation on the metabolic characteristics, performance, muscle, and mammary gland development and expression of genes involved in the urea cycle, and muscle tissue development of Holstein × Gyr crossbreed heifers grazing Brachiaria decumbens throughout the year. Thirty-eight heifers were randomly assigned to four treatments: three protein supplements (SUP) fed at 5g/kg of body weight, plus a control group. The supplement CP levels were 12, 24, and 36%. The experimental period was divided into four seasons: rainy, dry, rainy-dry transition, and dry-rainy transition. The data were analyzed using PROC GLIMMIXED of the SAS with repeated measures. SUP animals had a greater intake of dry matter, metabolizable energy, and metabolizable protein. Furthermore, SUP animals had a greater average daily gain, rib eye area and fat thickness than non-supplemented animals. Among SUP animals, we observed a quadratic response to ADG, with the highest level in S24. No supplementation effects were detected on mammary gland development. In muscle, we observed greater expression of AMPK in non-supplemented animals than SUP animals. No differences were observed for mTOR. We observed greater urea excretion and retention coefficient in SUP animals than non-supplemented animals. In this sense, we also observed greater gene expression of CPS, ASL, and ARG in SUP animals than non-supplemented, and among SUP animals, the supplement CP linearly affected CPS expression. We observed a positive linear effect of urea excretion, nitrogen intake, nitrogen retention, and retention coefficient among SUP animals. In conclusion, SUP animals had greater intake, performance than non- supplemented animals, with S24% demonstrating the best results. The third study aimed to describe the FA profile, as predicted using Fourier transform mid-infrared (FTIR) spectroscopy, of bulk tank milk from automated milking system (AMS) farms and to assess the association of management and housing factors with the bulk tank milk composition and FA profile of those AMS farms. The data used were collected from 124 commercial Canadian Holstein dairy farms. Information regarding individual cow milk yield (kg/d), days in milk (DIM), parity, and the number of milking cows were automatically collected by the AMS units on each farm. Multivariable regression models were used to associate herd-level housing factors and management practices with milk production, composition, and FA profile. Milk yield was positively associated with using a robot feed pusher (+2.1 kg/d) and the use of deep bedding (+2.6 kg/d). The use of a robot feed pusher, deep bedding, and greater stall raking frequency were positively associated with greater yield (kg/d) of de novo FA, mixed FA, preformed FA, and de novo + mixed FA. Greater frequency of PMR delivery (>2x/d vs. 1 and 2 x/d) was positively associated with a greater proportion (g/100 g of FA) of de novo, mixed, and de novo + mixed FA and negatively associated with the proportion of preformed FA. Overall, these associations indicate that bulk tank FA profile can be used to monitor and adjust management and housing in AMS farms. Keywords: Nitrogen metabolism. Pasture. Robotic milking. Season.
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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 | 0,000 |
| 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 | 0,000 | 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) | 0,000 | 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 ».