Mitigation strategies to reduce enteric methane emissions from dairy cows: Update review

Abstract

. 2004. Mitigation strategies to reduce enteric methane emissions from dairy cows: Update review. Can. J. Anim. Sci. 84: 319-335. Enteric methane (CH 4 ) emission is a major contributor to Canadian greenhouse gas emissions, and also a loss of feed energy during production. The objective of this paper is to provide an update on current management practices and new dietary strategies recently proposed to reduce CH 4 emissions from ruminants. Existing mitigation strategies for dairy, e.g., the addition of ionophores, fats, use of high-quality forages, and increased use of grains, have been well researched and applied. These nutritional changes reduce CH 4 emissions by manipulating ruminal fermentation, directly inhibiting methanogens and protozoa, or by diverting hydrogen ions away from methanogens. Current literature has identified new CH 4 mitigation options. These include the addition of probiotics, acetogens, bacteriocins, archaeal viruses, organic acids, plant extracts (e.g., essential oils) to the diet, as well as immunization, and genetic selection of cows. These new strategies are promising, but more research is needed to validate these approaches and to assess in vivo their effectiveness in reducing CH 4 production by dairy cows. It is also important to evaluate CH 4 mitigation strategies in terms of the total greenhouse gas budget and to consider the cost associated with the various strategies. More basic understanding of the natural differences in digestion efficiencies among animals as well as a better knowledge of methanogens and their interaction with other organisms in the rumen would enable us to exploit the potential of some of the new CH 4 mitigation strategies for dairy cattle production. Key words: Enteric methane, dairy cattle, mitigationBoadi, D., Benchaar, C., Chiquette, J. et Massé, D. 2004. Stratégies visant à réduire les dégagements de méthane entérique des vaches laitières: bilan. Can. J. Anim. Sci. 84: 319-335. Le méthane (CH 4 ) d'origine entérique contribue dans une large mesure aux émissions canadiennes de gaz à effet de serre et entraîne une perte de l'énergie tirée des aliments durant la production. Le présent article fait le point sur les pratiques de zootechnie actuelles et sur les stratégies d'engraissement récemment proposées pour réduire les dégagements de CH 4 des ruminants. Les stratégies d'atténuation existantes (addition d'ionophores, matière grasse, utilisation de fourrages de grande qualité, plus grande utilisation de grains) ont fait l'objet de maintes recherches et sont désormais bien appliquées. Les changements nutritionnels qu'elles introduisent diminuent les émissions de CH 4 en modifiant la fermentation dans le rumen, en inhibant directement la production de méthanogènes et la population de protozoaires ainsi qu'en détournant les ions hydrogène des méthanogènes. La documentation scientifique mentionne de nouvelles méthodes pour atténuer la libération de CH 4 . Ces méthodes comprennent l'ajout de probiotiques, d'acétogènes, de bactériocine, de virus archaïques, d'aci...

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