Lipids (level, nature, presentation)
Dietary fat seems a promising nutritional alternative to
depress ruminal methanogenesis without affecting other
ruminal parameters. Their effect has been assessed by
equations provided by Giger-Reverdin et al. (2003) and by
Euge` ne et al. (2008) who reported a mean decrease in CH4
of 2.2% per percentage unit of lipid added in the diet of
dairy cows, independently of the nature of fatty acid (FA)
supply. In their review paper based on 17 studies, Beauchemin
et al. (2008) reported a larger enteric CH4 reduction (5.6%
per 1% addition of lipids) for cattle and sheep. In a similar
way, we have summarised all publications in which CH4
emissions were measured in vivo and where different lipids
sources and forms of presentation were supplied to the
diet. A total of 67 diets supplied with lipids, taken from 28
publications were kept for analysis; 29 results were
obtained in open-circuit calorimetry chambers, 31 by the
SF6 method and six by other methods; 33 were obtained on
dairy cows, 13 on growing cattle, 16 on sheep at main-tenance and five on growing lambs. Other data (28 diets
supplied with lipids taken from six publications and two
abstracts) have been discarded because of an insufficient
description of methods or data, or because the control diet
was rich in lipids supposed to be inert. The relationship
obtained between level of added fat (% of DMI) and the
CH4 decrease (g/kg DMI) relative to the control diet is
presented in Figure 2. We observed a mean decrease in CH4
of 3.8% with each 1% addition of supplemental fat. It
clearly appears that the effect of FA is largely dependent on
their nature. Medium-chain FA, mainly provided by coconut
Lipids (level, nature, presentation)
Dietary fat seems a promising nutritional alternative to
depress ruminal methanogenesis without affecting other
ruminal parameters. Their effect has been assessed by
equations provided by Giger-Reverdin et al. (2003) and by
Euge` ne et al. (2008) who reported a mean decrease in CH4
of 2.2% per percentage unit of lipid added in the diet of
dairy cows, independently of the nature of fatty acid (FA)
supply. In their review paper based on 17 studies, Beauchemin
et al. (2008) reported a larger enteric CH4 reduction (5.6%
per 1% addition of lipids) for cattle and sheep. In a similar
way, we have summarised all publications in which CH4
emissions were measured in vivo and where different lipids
sources and forms of presentation were supplied to the
diet. A total of 67 diets supplied with lipids, taken from 28
publications were kept for analysis; 29 results were
obtained in open-circuit calorimetry chambers, 31 by the
SF6 method and six by other methods; 33 were obtained on
dairy cows, 13 on growing cattle, 16 on sheep at main-tenance and five on growing lambs. Other data (28 diets
supplied with lipids taken from six publications and two
abstracts) have been discarded because of an insufficient
description of methods or data, or because the control diet
was rich in lipids supposed to be inert. The relationship
obtained between level of added fat (% of DMI) and the
CH4 decrease (g/kg DMI) relative to the control diet is
presented in Figure 2. We observed a mean decrease in CH4
of 3.8% with each 1% addition of supplemental fat. It
clearly appears that the effect of FA is largely dependent on
their nature. Medium-chain FA, mainly provided by coconut
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