Comparison of alfalfa and mixed alfalfa-sainfoin pastures for grazing cattle: Effects on incidence of bloat, ruminal fermentation, and feed intake
Notice bibliographique
Résumé
Grazing experiments were conducted over two years to evaluate the effects of incorporating sainfoin (Onobrychis viciifolia) into alfalfa (Medicago sativa) pasture on bloat, ruminal fermentation, and feed intake. Pastures of alfalfa (Alf) and alfalfa-sainfoin (AS) were established by cross-seeding (in 1998) or parallel-seeding in (1999) sainfoin into strip-seeded alfalfa. The pastures were used in grazing studies in 1999 and 2000. For periods of 4 or 5 d, 12 ruminally cannulated Jersey steers were turned out into pastures from 0830 to 1430 daily (without access to water) then were moved to a fenced area (with free access to water but no feed) until the next morning. Feed intake during grazing was estimated using alkane markers, development of bloat was assessed, and ruminal fluid (RF) fermentation properties were determined. Incidence of bloat on first-growth pastures grazed at early bloom in 1999 was unaffected by sainfoin (at 8.3%, DM basis) but was reduced by 80% (P < 0.001) in AS pasture compared with Alf, when grazed at full-bud in 2000 (12.1% sainfoin). With re-growth forage, bloat incidence was decreased by 77% (P < 0.05) on pasture containing 35% sainfoin, but treatment effect was not observed on pastures containing < 23% sainfoin. Incidence of bloat was reduced as the proportion of sainfoin in herbage mass increased. In 2000, ruminal ammonia concentrations were reduced (P < 0.05) with mixed forage containing ≥ 12.1% sainfoin, compared with Alf. Protozoal numbers, RF viscosity, and total volatile fatty acids (VFA) were unaffected by sainfoin in the forage, but acetate:propionate ratios were consistently reduced (P ≤ 0.036). Extracellular polysaccharide-degrading enzyme activities in RF were increased (carboxymethylcellulase and β-glucanase, P ≤ 0.034; xylanase, P = 0.008 and 0.08) by sainfoin at ≥ 12.1%, and proteolytic activities (intracellular and extracellular) were reduced (P ≤ 0.01). Enzyme activities were unaffected by sainfoin at ≤ 9.1%. Sainfoin did not affect (P ≥ 0.202) organic matter intake from any of the pastures surveyed. Sainfoin was more effective for reducing bloat when cattle were grazing first growth pastures than when grazing re-growth. Including 35% sainfoin in mixed alfalfa-sainfoin pastures reduced, but did not eliminate, bloat in beef cattle and enhanced protein utilization by decreasing proteolytic activity. Feed efficiency may be improved through associative effects of the two forages. Key words: Alfalfa, beef cattle, feed intake, grazing, pasture bloat, sainfoin
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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) | 0,001 | 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 | 0,000 |
| 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 ».