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29 août 2016
- handle: 10670/1.l0de76
- isbn: 978-90-8686-284-9
- hal: hal-02742347
- PRODINRA: 371564
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Maguy Eugène et al., « Enteric methane emissions of cows in two contrasted low input dairy grassland-based systems », HALSHS : archive ouverte en Sciences de l’Homme et de la Société, ID : 10670/1.l0de76
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Livestock contributes to the environmental impact of agriculture with emissions of greenhouse gases. Extensive systems with low milk production per cow are often disadvantaged when emissions are expressed in g per kg of milk, as well as low input systems based on grasslands diet and using low concentrate. In this context, a study was conducted to acquire specific references on methane emissions (CH4) during the grazing season by measuring in vivo emissions of two dairy cows herds grazing pastures within two contrasted dairy grassland-based systems: an extensive system (Bota) managed with permanent grasslands highly diversified with no concentrate given to cows and an ecologically intensive system (Pepi) conducted with old temporary grasslands and moderate use of mineral fertilization and concentrate. In 2014 at the experimental farm of INRA located in uplands area of central France, two groups of 6 Holstein cows grazing in Pepi and in Bota systems were constituted. Individual measurements of enteric CH4 emission using the SF6 technique and milk production were performed one week in June (P1) and one in July (P2). Simulated bites were sampled at grazing at the two periods. In P1, CH4 emission of Bota and Pepi cows, expressed either in daily emission or per milk production, were similar (respectively 402 g/d, 16 g/kg MY). In P2, CH4 emissions of Bota cows tended to be higher than those of Pepi (400.3 vs 330.5 g/d). The lack of significant difference between the two systems could be related to the low amount of concentrate given to Pepi cows, to the similarity of the botanical family composition of the cows bites and finally to the low difference of milk production between the two systems at this grazing period. These values corresponded to the high range of emission found in the literature, but not when expressed per unit of surface.