Methane abatement strategies for cattle: Lipid supplementation of diets
Notice bibliographique
Résumé
A study was conducted to investigate the impact of several lipid sources that supplied mainly long-chain fatty acids (FA), for their potential to reduce methane emissions from growing cattle. Sixteen Angus heifers (initial weight, 325 ± 41 kg) were used in the experiment, which was designed as a crossover with two groups, four 21-d periods, and four dietary treatments: control (no added lipid source), tallow, sunflower oil, and whole sunflower seeds. Lipid sources were added to supply 34 g fat kg -1 of dietary dry matter (DM), bringing the total dietary fat content to about 59 g kg -1 of DM. Adding tallow increased the dietary proportion of saturated FA (47 g 100 g -1 of FA), whereas sunflower oil and seeds decreased the proportion (21 g 100 g -1 of FA). The basal diets consisted of mainly whole-crop barley silage (650 g kg -1 of DM). Compared with the control, ad libitum intake was reduced (P < 0.001) with sunflower seeds, but not with tallow (P = 0.13) or sunflower oil (P = 0.53). About 14% less methane was emitted per animal when diets contained tallow or sunflower oil and 33% less methane was emitted when diets contained sunflower seeds (P < 0.001), compared with the control diet (177.4 g d -1 ). Relative differences in methane emissions among lipid sources were maintained after correction for intake of DM or gross energy. The methane reduction caused by tallow and sunflower seeds was partly due to decreased diet digestibility. Digestibility of neutral detergent fiber in the total tract decreased (P < 0.05) by 15% with tallow and by 20% with sunflower seeds compared with the control, with only a numerical reduction from control for sunflower oil (12%; P = 0.11). Consequently, digestible energy intake was about 4% higher (P < 0.001) for sunflower oil, but 3% lower (P = 0.02) with tallow and 12% lower (P < 0.001) with sunflower seeds, compared with the control. All lipid sources reduced methane emissions by an average of 17% when corrected for digestible energy intake (from 11.22 to 9.34 g methane Mcal -1 ; P = 0.01). We concluded that adding about 3% lipid to high-forage diets in the form of saturated or unsaturated long-chain FA decreases methane emissions, and could have substantial effects on methane inventories if implemented commercially. All three lipid sources suppressed methane production, but sunflower oil has good potential for on-farm adoption because it had minimal effects of fiber digestibility, increased the intake of digestible energy and the rate of gain of cattle, and lowered methane production. Although tallow and sunflower seeds are usually cheaper sources of lipid than sunflower oil, their cost effectiveness as methane abatement strategies would also need to account for their potentially negative effects on digestible energy intake and performance of cattle fed high-forage diets. key words: Beef cattle, diet, fat, greenhouse gases, lipid; methane, oil
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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) | 0,001 | 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) | 0,001 | 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 ».