The present invention relates in particular to a method for evaluating the amount of methane produced by a dairy ruminant. It is characterized in particular in that it comprises the determination of the ratio between the amount of fatty acids with 16 carbon atoms or less, termed FA<;C16, and the sum of the total fatty acids of the milk, wherein said fatty acids are those present in the milk produced by said ruminant, and wherein said amount of methane is defined by the following equation: amount CH