Methane emissions from dairy cows: influence of oilseeds in the feed

The addition of fatty feed components to a dairy cow ration can influence ruminal fermentation, and hence methane formation in the rumen. In a study with 33 Holstein / Red Holstein dairy cows, the influence of two different types of oilseeds (extruded linseed and ground rapeseed) versus a control (rumen-stable fat) was investigated over a period of 12 weeks in terms of its impact on feed intake, milk yield, ruminal fermentation and methane emission. The feed intake and milk production of the individual animals was recorded daily. In addition, the milk constituents from an evening and morning milking of each animal were analysed on a weekly basis. Individual weekly methane release data were collected at two GreenFeed stations. In weeks 6, 9, 12 and 15 of the trial, ruminal fluid was sampled from 18 cows (six per treatment) using an esophageal probe and analysed for volatile fatty acids, ammonia, and selected microorganisms. Cows that were fed the extruded linseed consumed less feed and their milk had a lower fat content, although they produced more milk per day. Both types of oilseeds led to a 7% reduction in daily methane production in dairy cows, which was accompanied by a reduction in the relative incidence of methanogens in the rumen. Methane intensity (g/kg of energy corrected milk) was numerically reduced by 15 – 17% with both types of oilseeds. We conclude from the present study that a certain reduction in methane emissions can be achieved with oilseeds, but that the amount of reduction varies in terms of intensity according to the calculation basis used.

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