Variation in methane emissions from lactating dairy cows measured with a GreenFeed unit

Because of its contribution to global warming, methane production is a major drawback of the unique capacity of ruminants to convert non-edible, fiber-rich feeds into human edible foods. Mitigation strategies are needed and one of the possible options is nutritional intervention. Daily methane emissions from cows treated for at least seven weeks with potential methane reducing feed additives, were used to assess the between-cow and within-cow variation. The individual daily methane production (CH4) was measured using a GreenFeed unit. Daily dry matter intake (DMI) and milk production (MP) were monitored. Across four different trials, the individual within-cow coefficient of variation (CV) for g CH4/kg DMI ranged from 1,6% to 25,4% with a mean of 13,1% and for g CH4/kg MP the CV ranged from 2,2% to 31,1%, with a mean value of 12,6%. A narrow between-cow CV range was observed when expressing CH4 (g) per kg DMI: from 10,2% to 12,4%, with a mean of 11,1%. The range of the between-cow CV for g CH4/kg MP was larger, from 11,8% to 24,3%, with a mean CV of 18,6%.